Systems
Immune System
Musculo-skeletal System
Cardiovascular system
Endocrine System
Nervous System
Digestive System
Respiratory System
Lymphatic System
Integration System
Microbiome
Metabolic System
Physiology
Normal Biological Function
Environment
Hormetic stressors
Low toxic exposure
Proactive in maintaining health
Life has meaning and purpose
Feels safe
Whole-foods ancestral diet
Restorative rest and movement
Systems
Musculo-skeletal System
Nervous System
Light and nature exposure
Joyful movement
Endocrine System
Digestive System
Cardiovascular system
Respiratory System
Metabolic System
Immune System
Microbiome
Symptoms
Calm
Strong
Integration System
Lymphatic System
Relaxed
Flexible
Stable energy
Resilient
Clear vision
Reliable sleep
Flows through menstrual cycle / menopause with ease
Clear-headed
Smooth digestion
Able to overcome difficulties
Adaptable
Environment
Low toxic exposure
Life has meaning and purpose
Restorative rest and sleep
Whole-foods ancestral diet
Proactive in maintaining health
Feels safe
Light and nature exposure
Hormetic stressors
Joyful movement
Symptoms
Calm
Flexible
Stable energy
Resilient
Relaxed
Reliable sleep
Clear vision
Adaptable
Strong
Smooth digestion
Flows through menstrual cycles and menopause with ease
Clear-headed
Able to overcome difficulties
HumanBody Anatomy
Start
Human skeleton
Front part
The human skeleton is formed by more than 200 bones that provide support and protection to internal organs; and also enable movement through joint action with muscles. Its symmetrical structure helps us maintain balance and an upright posture.
+200
12%
of body weight
bones
Bones account for approximately 12% of total body weight. Although they are lightweight, they are extremely strong and durable.
The adult human body has 206 bones, organized into the axial skeleton (skull, spine, ribs) and the appendicular skeleton (limbs).
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Human skeleton
Back
The human skeleton viewed from the back includes fundamental bony structures such as the spine, scapulae, posterior ribs, pelvis, and limb bones. These parts work together to provide support, protect the spinal cord and internal organs, and enable body movement. The spine aligns from the base of the skull to the pelvis, while the scapulae and humerus allow arm movement. At the bottom, the sacrum, coccyx, and leg bones support the body upright and facilitate movement.
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Osteology of the skull
Bone structure and main functions
The skull is composed of a set of bones that protect the brain and form the facial structure. It is divided into two main parts: the neurocranium, which surrounds and protects the brain, and the viscerocranium, which shapes the facial structure. The neurocranium includes bones such as the frontal, parietal, temporal, occipital, sphenoid, and ethmoid. These bones are joined by sutures, which are immovable joints that allow controlled growth during childhood.
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Muscular System
The muscular system is essential for movement and stability of the body.
They are divided into skeletal, cardiac, and smooth muscles. Skeletal muscles enable voluntary movements, cardiac muscles control heartbeat, and smooth muscles regulate automatic internal functions:
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muscles work together to maintain posture, facilitate movement, and generate body heat.
Nervous system
Coordinates and regulates body functions throughelectrical and chemical impulses
The nervous system allows communication between the brain, spinal cord, and the rest of the body. It is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves and ganglia), and controls both voluntary and automatic functions. It processes environmental stimuli, regulates internal organs, and is essential for activities such as thinking, movement, and emotions. Neurons are its main cells, transmitting signals via electrical impulses and neurotransmitters, ensuring quick and precise responses.
Digestive system
Set of organs responsible for transformingfood into nutrients for the body.
The digestive system processes food through mechanical and chemical digestion, absorbs nutrients, and eliminates waste. It begins in the mouth and ends at the anus, including organs such as the stomach, intestines, liver, pancreas, and gallbladder.
Stomach
Pancreas
Gallbladder
Produces digestive enzymes and hormones like insulin.
Stores and releases bile, a liquid that helps digest fats.
Mixes food with gastric juices to initiate protein digestion.
Respiratory system
The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. This process is essential for cellular respiration and energy production.
01.
Nasal cavities and nasal cavity
They filter, humidify, and warm the inspired air. Mucous membranes and hairs trap particles and microorganisms.
Pharynx and larynx
02.
The pharynx connects the respiratory tract with the esophagus. The larynx contains the vocal cords and allows air to pass into the trachea.
Trachea and bronchi
03.
The trachea is a reinforced tube with cartilaginous rings that divides into bronchi, which carry air to each lung.
Lungs and alveoli
04.
Lungs contain millions of alveoli, where gas exchange occurs: oxygen passes into the blood and CO₂ is eliminated.
Circulatory system
The circulatory system is responsible for transporting blood, oxygen, and nutrients throughout the body. It is composed of the heart, arteries, veins, and capillaries. Arteries carry oxygen-rich blood from the heart to the tissues, while veins return blood with carbon dioxide. This system is vital for organ function and maintaining the body's internal balance.
Veins
Arteries
Female reproductive system
Organs responsible for reproduction, gestation, and childbirth
The female reproductive system is made up of internal and external organs. Its main function is to enable fertilization, embryo development, and childbirth. Internal organs include ovaries, fallopian tubes, uterus, and vagina. External organs form the vulva, which protects the entrance to the reproductive system. In addition to its reproductive role, it also participates in the production of sex hormones such as estrogen and progesterone, which are essential in the menstrual cycle.
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Male reproductive system
Organs responsible for sperm and sex hormone production
The male reproductive system is made up of internal and external structures. Its main function is to produce, store, and transport sperm, as well as secrete testosterone.
- Testicles: produce sperm and testosterone.
- Epididymis: stores and matures sperm.
- Vas deferens: transports sperm to the urethra.
- Seminal vesicles: secrete part of the seminal fluid.
- Prostate: produces part of the semen and aids sperm mobility.
- Bulbourethral glands: lubricate the urethra before ejaculation.
- Penis: external organ responsible for copulation and semen expulsion.
- Urethra: duct that transports semen and urine outside.
- Scrotum: pouch that protects and regulates testicular temperature.
- Prepuce: fold of skin covering the glans of the penis.
Lymphatic system
Defense and balance in the human body
The lymphatic system is a network of vessels, lymph nodes, and organs that protects the body from infections and diseases. Its main function is to transport lymph, a clear fluid containing white blood cells, nutrients, and cellular waste. What does this system do?
- Defends the body by filtering bacteria and viruses through the lymph nodes.
- Maintains fluid balance in the tissues.
- Absorbs fats from the digestive system through structures called lacteals.
What do we see here? The image shows a lymph node, where lymph is filtered. Inside, lymphocytes (a type of white blood cell) identify and attack harmful agents before they spread through the body.
Excretory system
The excretory system is responsible for removing waste from the body to maintain internal balance. Organs such as the kidneys, bladder, and skin work together to filter, transport, and expel substances that are no longer useful. Without this system, the body would accumulate toxins that could impair its functioning.
What is the function of the excretory system in the human body?
01.
Blood filtration
The kidneys filter the blood to remove waste such as urea and excess salts. This process produces urine, which will later be expelled from the body.
02.
Transport and storage
The ureters carry urine from the kidneys to the bladder, where it is stored temporarily. When necessary, urine is expelled through the urethra.
Elimination of toxins through other pathways
03.
In addition to urine, the body eliminates waste through sweat and breathing. The skin and lungs also participate in the excretion of unwanted substances.
Metatarsals
The metatarsals are five long bones that form the middle part of the foot, between the tarsal bones and the toe phalanges. They are essential for maintaining the arch of the foot and allow movements that facilitate walking and balance. Thanks to their arrangement, the metatarsals help to distribute body weight when walking, running, or jumping, and provide support for the musculature and ligaments of the foot.
Popliteal lymph nodes
They are behind the knees and filter the lymph from the feet, legs, and lower thighs. Although small, they serve an important role in local immune defense. Their inflammation can indicate infections or injuries in the legs or feet.
Latissimus dorsi
It is one of the largest muscles in the body. It covers the lower part of the back and inserts into the humerus. It participates in extension, adduction, and internal rotation of the arm. It is key in movements like rowing, swimming, or climbing.
65%
+178
automatic functions
water
The body is composed of about 65% water, a vital element for all cell functions and for maintaining a stable body temperature.
The human body performs over 178 automatic functions daily, such as breathing, blinking, or regulating body temperature, all without us realizing!
32%
+45
heartenergy
activedefenses
Approximately 32% of the energy produced by the body is allocated to keeping the heart and circulatory system functioning.
The immune system uses more than 45 types of cells to defend us from viruses, bacteria, and other external agents.
Frontal
The frontal bone forms the forehead and protects the frontal lobe of the brain. It is key for functions such as thinking and control of movement, as well as shaping the face.
Large intestine
Absorbs water and forms the stool from the undigested material in the small intestine.
Pulmonary veins
Carry oxygenated blood from the lungs to the heart. They flow into the left atrium.
Tibial arteries
Branches of the popliteal: anterior and posterior. They supply the anterior and posterior compartments of the leg.
Uterus
Hollow organ where the embryo develops during pregnancy; it is formed by the endometrium, myometrium, and perimetrium.
Pulmonary veins
Although they are veins, they carry oxygenated blood. They carry blood from the lungs to the left atrium of the heart.
Immune System
Surveillance, Communication, and Repair
Fascinating FactThe body naturally allows the presence of some self-reactive B-cells and T-cells. This is part of normal function because there are invadors and cancerous cells that we want to be protected against. The immune system has several mechanisms in place to make sure that these self-reactive cells stay on task and keep the peace.
This distributed network of cells, tissues, and signalling molecules is responsible for identifying, neutralising, and removing threats while maintaining the integrity of the body’s own tissues. It functions through a balance of activation and regulation rather than constant defence. Immune activity is continuously shaped by the nervous system, the endocrine system, and the metabolic state of each cell. The immune system therefore acts as both sensor and effector—interpreting information from the environment, microbiome, and internal milieu, and translating it into tissue repair or defence.
More information on the immune system
Main bronchi
Two ducts that originate from the trachea and lead to each lung. They are the main airways to the lungs.
Spinal column
The spine is a central bony structure that runs from the base of the skull to the pelvis. It is made up of 33 vertebrae grouped into five regions: cervical, thoracic, lumbar, sacral, and coccygeal. Its main function is to protect the spinal cord and support the body. Thanks to its natural curves and intervertebral discs, it allows flexibility, impact absorption, and movements such as bending, twisting, and standing upright.
Humerus
The humerus is the long bone of the arm that extends from the shoulder to the elbow. It articulates with the scapula at its upper end and with the radius and ulna at the lower end. It is essential for arm movements, as it supports muscles that allow lifting, rotating, and flexing. It also protects important nerves that pass through this area.
Internal carotid arteries
They originate from the common carotids and penetrate the skull. They irrigate the anterior brain and ocular structures.
Cephalic vein
Drain the lateral part of the arm and forearm.Connects to the axillary vein near the shoulder.
Phalanges
The phalanges are the bones that form the toes. Each of them has three phalanges —proximal, middle, and distal— except for the big toe, which only has two. These small bony structures allow movement of flexion and extension that are fundamental to maintain balance and the stability when walking or running. Additionally, they protect nerve endings and soft tissues at the tips of the toes.
Inguinal lymph nodes
They are located in the groin and filter lymph from the legs, feet, and pelvic region. They often become inflamed due to infections or wounds in the lower limbs. They are key in detecting problems in the lower part of the body.
Ulnar nerve
Branch of the brachial plexus. It runs through the arm to the hand, where it innervates the little finger and ring finger, as well as intrinsic muscles of the hand. It is responsible for fine motor skills and often causes the sensation of “electric shock” when hitting the elbow (nerve of the “little bone”).
Popliteal arteries
Located behind the knee. Irrigates the posterior region of the knee and the leg.
Superficial flexor ofthe fingers
This muscle flexes the middle joints of the fingers, allowing them to bend partially. It is essential for grip function in the hand.
Deep femoral vein
Collect blood from the deep muscles of the thigh. It joins the main femoral.
Iliac veins
Blood is drawn from the lower limbs and pelvis. They form the inferior vena cava when they join.
Gluteus maximus
It is the largest and most superficial muscle of the glutes. It is responsible for extending and rotating externally the hip. It is essential for standing up, climbing stairs, and running. It also shapes and adds volume to the gluteal region.
Ilium
The ilium is the largest and uppermost part of the hip bone, located in the pelvis, above the pubis and the ischium. It is responsible for supporting the body's weight in an upright position and connects to the spine through the sacroiliac joint. Thanks to its broad and curved shape, the ilium provides attachment for numerous muscles of the trunk and lower limbs. Additionally, its structure helps to protect internal organs such as the intestines and part of the reproductive system.
Rhomboid Muscle
Located between the shoulder blades and the spine, the rhomboid muscle (major and minor) retracts the scapula, bringing it closer to the spine. It also contributes to its elevation and rotation. It is essential for maintaining a good posture and shoulder stability.
Liver
Organ that produces bile, processes nutrients, and detoxifies harmful substances in the body.
Inner vastus (Vastus medialis)
This muscle is located on the inner part of the thigh. Its function is to extend the leg at the knee joint and to stabilize the kneecap.
Peronealarteries
Posterior tibial branch. Irrigates the lateral compartment of the leg.
Basilic vein
Located in the medial part of the arm.Connects to the brachial to form the axillary vein.
Popliteal vein
Located behind the knee. Collects blood from the leg and drains into the femoral vein.
Thymus
It is an organ located behind the sternum, activemainly in childhood. There, T lymphocytes mature, which are essential for the immune system. Over time, the thymus decreases in size and activity.
Upper lobar bronchi
Branches that carry air to the upper lobe of both lungs. They branch from the main bronchi.
Gluteus medius
Located on the side of the hip. Its main function is the thigh abduction (separating the leg from the body) and the pelvic stabilization during walking or when standing on one leg.
Nasal cavity
Structure that filters, warms, and humidifies the air we breathe. It is the main entry point of the respiratory system
Trapezius
The trapezius muscles are large and triangular muscles located at the top of the back and neck. Their main function is to move, elevate, and stabilize the scapula, as well as extend and rotate the neck. They are essential for movements of the shoulder and the head.
Basilar artery
It is formed by the union of the two vertebral arteries. It supplies the brainstem, cerebellum, and part of the posterior brain.
Internal jugular vein
Drains blood from the brain, face, and neck. It joins the subclavian vein to form the brachiocephalic vein.
Soleus
Located beneath the gastrocnemius in the calf, the soleus allows plantar flexion (pushing the foot downward) and is crucial for standing and walking.
Radial artery
Another branch of the brachial artery is located on the lateral part of the forearm. Important in hand irrigation and radial pulse measurement
Metacarpals
The metacarpals are a group of five long bones located in the hand, between the wrists and the fingers. They form the central structure of the palm and enable the necessary movement and stability to perform precise movements with the hand. Thanks to their joint with the carpal bones and the phalanges, the metacarpals facilitate actions such as grabbing, holding, and manipulating objects. Additionally, they provide support and protection to the nerves and blood vessels that pass through the hand.
Lower jaw
The lower jaw, or mandible, is the movable bone of the face. It allows chewing and forms the lower structure of the face.
Vertebral arteries
They originate from the subclavian arteries and ascend through the cervical vertebrae. They supply blood to the posterior brain, spinal cord, and cerebellum.
Appendix
Although its function is debated, the appendix contains lymphatic tissue. It is believed to contribute to the immune system in early stages of life. It can become inflamed, causing appendicitis, a common medical emergency.
Ulna
The ulna is one of the two bones of the forearm, located on the pinky side. It extends from the elbow to the wrist and works together with the radius to allow arm movement and forearm stability. At its upper end, it forms part of the elbow joint, and at the lower end, it connects with the wrist bones. It is essential for the movements of extension and flexion of the arm.
External carotid arteries
Superficial structures of the head, face, and neck are irritated. They have multiple branches that supply muscles, glands, and skin.
Atlas
The atlas is the first cervical vertebra of the spine, located just below the skull. Its main function is to support the head and allow movements such as nodding. Unlike other vertebrae, the atlas has no vertebral body, giving it a ring-shaped and lightweight form. Together with the axis (second cervical vertebra), it forms a joint that facilitates neck mobility.
Sciatic nerve
The longest nerve in the body originates from the sacral plexus. It descends through the leg and innervates the posterior thigh muscles and the entire leg. Compression or irritation of the sciatic nerve causes pain that radiates from the lower back to the foot (sciatica).
Femoral vein
Transporta sangre desde la pierna al abdomen. Se convierte en la ilíaca externa al pasar por la ingle.
Common carotid arteries
Located on both sides of the neck. They bifurcate into the internal and external carotid at the level of the larynx.
Palmar longus
Thin muscle of the forearm, absent in some people. Assists in flexion of the wrist and in tensioning the palmar aponeurosis (palm tissue).
Pancreas
Secretes digestive enzymes into the small intestine and hormones like insulin into the blood.
Esophagus
Muscular tube that transports food from the pharynx to the stomach through peristaltic movements.
Iliac arteries
Arise from the bifurcation of the abdominal aorta. They irrigate the pelvis and lower limbs.
Median cubital vein
Connect the basilic and cephalic veins at the elbow.It is commonly used for blood withdrawal.
In turn, the viscerocranium is composed of bones such as the maxilla, mandible, nasal, zygomatic and others, which shape the face and house structures like the eyes, nose, and mouth. Additionally, the skull has openings called foramina, through which nerves and blood vessels pass, essential for brain and sensory functions. Thanks to its complex structure, the skull not only protects the central nervous system, but also serves as support for muscles that enable mastication and facial expression, being fundamental for daily life.
Gastrocnemius
This muscle forms the most visible part of the calf. It aids in the plantar flexion of the foot and also contributes to flexing the knee.
Dorsal metatarsal venous arch
Venous redness on the top of the foot.Drains into the saphenous veins.
Talus
The talus is a bone of the tarsus located between the tibia, fibula, and calcaneus. It is fundamental for the ankle joint and allows movements such as flexion and extension of the foot. Thanks to its strategic position, the talus transmits the body's weight from the leg to the foot and contributes to stability and mobility during walking.
Calcaneus
The calcaneus is the largest bone in the foot and forms the heel. It is located at the back of the tarsus and articulates with the talus and the cuboid, participating in the formation of the ankle and the arch of the foot. Thanks to its robust structure, it supports the body's weight when walking, running, or standing. Additionally, it serves as an insertion point for the Achilles tendon, enabling the movement of the foot downward.
Occipital
The occipital bone is located at the back and bottom of the skull and protects the occipital lobe of the brain. It is essential for functions such as vision and balance, in addition to connecting the skull with the spine.
Teres major
Located below the lesser tubercle, this muscle connects the scapula with the humerus. It allows extension, adduction, and internal rotation of the arm. It supports the latissimus dorsi in pulling movements.
Ureter
It is a thin tube that connects each kidney to the bladder. It transports urine through muscle contractions called peristalsis. Each person has two ureters, one for each kidney.
Parietal
The parietal bones form the upper and lateral part of the skull. They protect the brain and participate in the structure of the skull, providing support and shape.
Radial nerve
Posterior branch of the brachial plexus. It innervates the extensor muscles of the arm, forearm, and wrist, and provides sensation to the back of the hand. It is essential for extending the elbow, wrist, and fingers, and it is frequently affected in compression injuries.
Kidney
The kidneys filter the blood to remove waste and excess fluids. They convert these wastes into urine, which is then excreted. They also help control blood pressure and the body's chemical balance.
Shoulder blades
The scapulae, also known as shoulder blades, are two flat and triangular bones located on the back of the thorax. They articulate with the humerus and clavicle, forming a key part of the shoulder joint. Thanks to their shape and mobility, they allow a wide range of arm movements and serve as an anchor point for various muscles. Additionally, they contribute to the stability and flexibility of the shoulder girdle.
Vas deferens
It is a tube that transports sperm from the epididymis to the ejaculatory duct. It functions during ejaculation through muscular contractions.
Oblique
Located on the sides of the abdomen, this muscle allows rotation and lateral flexion of the trunk. It also helps with compression of the abdomen and breathing control.
Segmental bronchi
Branches of the lobar bronchi that carry air to specific lung segments.
Brachioradialis
The brachioradialis is a muscle of the forearm that allows elbow flexion, especially when the forearm is in a neutral position (such as when lifting a bottle). It is visible on the outer part of the forearm.
Radial flexorof the wrist
This forearm muscle allows flexion and deviation of the wrist toward the thumb side. It is important in precise hand movements such as writing or gripping small objects.
Bladder and urethra
The bladder stores urine until it is expelled. The urethra transports both urine and semen outside the body.
Ovaries
Glands that produce eggs and sex hormones such as estrogen and progesterone.
Axillary arteries
Continuation of the subclavian arteries in the axilla. They irrigate the upper part of the thorax, shoulder, and proximal arm.
Celiac trunk
First branch of the abdominal aorta. Supplies the stomach, liver, spleen, and part of the pancreas.
Kneecap
The kneecap, also known as patella, is a small bone located at the front of the knee. It functions as a shield that protects the joint and improves the efficiency of the quadriceps muscle by extending the leg. Thanks to its position, the kneecap facilitates knee movement and helps to distribute pressure during activities such as walking, running, and jumping, contributing to leg stability.
Lumbar column
The lumbar column is made up of 5 large and robust vertebrae, located in the lower back. These vertebrae support most of the body weight and allow movements such as bending or twisting the torso. They also protect the lower end of the spinal cord and serve as an anchor for muscles that stabilize the trunk and help us stand upright.
Pubic symphysis
The pubic symphysis is a cartilaginous joint that connects the two pubic bones at the front of the pelvis. It is composed of a cartilaginous disc that provides stability but also some flexibility. Its main function is absorbing impacts and allowing slight pelvic mobility, especially important during pregnancy and childbirth. It also contributes to body stability when walking or standing.
Lumbricals
The lumbricals are small muscles of the hand, located between the tendons of the deep flexor muscles of the fingers. They are responsible for flexing the metacarpophalangeal joints and extending the interphalangeal joints, facilitating fine finger movements. Thanks to their coordinated action, the lumbricals allow precise gestures such as writing or playing an instrument.
Lymph nodesof the thorax
They filter lymph from the lungs, heart, and other thoracic structures. They participate in protection against respiratory infections. They are also evaluated in diseases such as tuberculosis or cancer.
Fibula
The fibula is a long, slender bone located alongside the tibia, on the lateral side of the leg. Although it does not bear much of the body's weight, it is essential for ankle stability and leg mobility. Thanks to its location, the fibula provides attachment points for muscles and ligaments, contributing to balance and flexion of the foot. Additionally, it protects nearby nerve and vascular structures.
Gonadal arteries
They occur in the testes in men and the ovaries in women. They originate from the abdominal aorta.
Small intestine
Absorbs most nutrients thanks to its large surface area formed by intestinal villi.
Lumbar plexus
It originates from the nerve roots L1 to L4. It innervates the abdomen, pelvis, and front part of the thigh. Key nerves such as the femoral and obturator nerves come from it, which control muscles for walking and standing.
Saphenous nerve
It is a sensory branch of the femoral nerve. It runs along the inner part of the leg and foot. Its function is exclusively sensory, providing sensation to the medial surface of the leg and ankle.
Left lung
Respiratory organ composed of two lobes. It exchanges gases with less volume than the right one.
Brachial plexus
Nerve network that originates in the spinal cord, from the roots C5 to T1. It supplies shoulder, arm, forearm, and hand. It is essential for the movements and sensation of the upper limbs. Important nerves such as the radial, ulnar, and median nerves branch from it.
Digital veins
They bleed from the fingers of the hands and feet.Connect to dorsal and palmar venous networks.
Renal veins
Drain blood from the kidneys. They drain directly into the inferior vena cava.
Cervical lymph nodes
They are located in the neck and filter the lymph coming from the head and the upper neck region. They help detect and fight infections such as colds or tonsillitis. They tend to swell when the body responds to an infection.
Femur
The femur is the longest and strongest bone in the human body. It is located in the thigh, connecting the hip to the knee and supporting much of the body's weight. Thanks to its sturdy structure, the femur allows movements such as walking, running, and jumping. Additionally, it protects the bone marrow and provides attachment points for important muscles that control leg mobility.
Carpal bones
The carpal is made up of 8 small bones arranged in two rows, which form the base of the hand. These bones articulate with the radius, ulna, and metacarpals, allowing wrist mobility. Thanks to their shape and arrangement, the bones of the carpal provide flexibility and strength, facilitating movements such as rotating, bending, or extending the hand with precision.
Deltoid
The deltoid covers the shoulder and is divided into three portions: anterior, middle, and posterior. It allows lifting the arm forward, to the side, and backward, being essential in the arm abduction. It also contributes to the rounded shape of the shoulder.
Nasal bone
The nasal bones form the bridge of the nose. They serve as support for the nasal structure and protect the upper respiratory tracts.
Immune System
Surveillance, Communication, and Repair
Fascinating FactThe body naturally allows the presence of some self-reactive B-cells and T-cells. This is part of normal function because there are invadors and cancerous cells that we want to be protected against. The immune system has several mechanisms in place to make sure that these self-reactive cells stay on task and keep the peace.
This distributed network of cells, tissues, and signalling molecules is responsible for identifying, neutralising, and removing threats while maintaining the integrity of the body’s own tissues. It functions through a balance of activation and regulation rather than constant defence. Immune activity is continuously shaped by the nervous system, the endocrine system, and the metabolic state of each cell. The immune system therefore acts as both sensor and effector—interpreting information from the environment, microbiome, and internal milieu, and translating it into tissue repair or defence.
More information on the immune system
Larynx
Contains the vocal cords and regulates the airflow to the trachea. Participates in voice production.
Sacrum
The sacrum is a triangular bone formed by the fusion of five vertebrae located at the base of the spine. It is situated between the two parts of the pelvis bone and connects the spine with the hip bone. It acts as a support point for the upper part of the body and distributes weight to the legs. Additionally, it protects important nerves that extend toward the lower part of the body.
Clavicle
The clavicle is a long and slender bone that connects the sternum with the scapula. It is located at the top of the chest and is visible and palpable just below the neck. Its main function is to keep the arm separated from the trunk, allowing greater shoulder mobility and acting as support for the neck and shoulder muscles.
Sacral spinal nerves
They are five pairs (S1 to S5) emerging from the sacrum. They control motor and sensory functions of the pelvis and lower limbs. They also participate in sphincter control and in the sensitivity of the perineal region.
Testicle
Sperm and testosterone-producing organ, located inside the scrotum.
Intercostal muscles
These muscles are located between the ribs and are divided into external and internal. They participate in breathing: the external muscles help expand the chest during inhalation, and the internal muscles help reduce it during exhalation.
Triceps brachii
Located at the back of the arm, it has three heads (long, lateral, and medial). Its main function is to extend the elbow. It also participates in shoulder extension when the long head is activated.
Cervix
Also called the cervix, it is the lower part of the uterus that connects to the vagina and regulates the passage of sperm and menstrual flow.
Dorsal digital veins
Blood drains from the toes. They connect to the dorsal venous arch.
Aorta
It is the main artery of the body. It carries oxygen-rich blood from the heart to the entire body.
Pharynx
Muscular tube connecting the mouth to the esophagus and directing food toward the digestive system.
Acetabulum
The acetabulum is a cup-shaped cavity located in the pelvic bone. It is part of the hip joint as it receives the head of the femur, allowing leg movement in various directions. Thanks to its deep shape and reinforced by a ring of cartilage called labrum, it provides stability to the joint. Additionally, it distributes body weight from the pelvis to the lower limbs.
Superior vena cava
Carries deoxygenated blood from the upper part of the body to the heart. Drains into the right atrium.
Deep femoral arteries
Important branch of the femoral artery. Supplies deep muscles of the thigh.
Tensor of the fascia lata
This muscle is located on the lateral part of the hip and acts by tightening the fascia lata (tissue that surrounds the thigh muscles). It contributes to stabilization of the knee and hip during walking.
Mammary gland
The mammary gland is a set of glandular structures in the chest tissue. Its main function is the production and secretion of breast milk during breastfeeding. It is present in both women and men, although less developed in the latter.
Pubis
The pubis is one of the three parts that make up the hip bone, located at the front of the pelvis. Both sides of the pubis meet in the center through an joint called pubic symphysis. This bone supports the lower abdominal organs and is key in the structure of the pelvic floor. It also plays an important role in posture and body balance.
Subclavian arteries
Supply blood to the arms, neck, and part of the brain. Give rise to the vertebral and axillary arteries.
Brachial arteries
Prolongation of the axillary artery in the arm.It irrigates the muscles and tissues of the arm and divides into radial and ulnar.
Internal iliac veins
Blood drains from the pelvic organs. They join the external iliacs to form the common iliacs.
Liver
Organ that produces bile, processes nutrients, and detoxifies harmful substances in the body.
Spleen
It is the largest lymphatic organ and is located in the abdomen, near the stomach. Filters blood, removes old cells, and stores white blood cells. Helps fight infections and maintain blood balance.
Bladder
It is a hollow organ that stores urine before it is expelled. It expands and contracts depending on the amount of urine it contains. When it fills, it sends signals to the brain to initiate urination.
Semimembranosus
It is the deepest of the hamstrings. It helps to bend the knee, extend the hip, and rotate the leg internally. Along with the semitendinosus and the biceps femoris, it stabilizes the pelvis.
Lesser tubercle
The lesser tubercle is a small muscle of the rotator cuff. It originates from the scapula and inserts into the humerus. Its main function is externally rotating the arm and stabilizing the shoulder joint.
Suprahepatic veins
They drain blood from the liver into the inferior vena cava.They are essential for hepatic venous return.
Ulnar extensor of the wrist
Located on the back of the forearm, this muscle allows to extend and adduct (move inward) the wrist. It contributes to hand stability and is important in pushing movements.
Rectus abdominis
This muscle is located in the front part of the abdomen and is responsible for flexing the spine, maintaining posture, and containing the internal organs. It is part of the group known as “core”.
Tibial veins
Drain blood from the anterior and posterior regions of the leg. They join the popliteal vein.
Radius
The radius is one of the two bones of the forearm, located on the thumb side. It extends from the elbow to the wrist and works together with the ulna to allow arm movement and hand rotation. Thanks to the radius, we can turn the palm upward or downward, and perform precision movements essential in daily activities.
Cervical column
The cervical column is made up of the first 7 vertebrae of the spine. It is located in the neck and is responsible for supporting the skull and allowing head movement. Thanks to its flexibility, we can rotate, tilt, and extend the neck. Additionally, it protects the spinal cord as it travels toward the rest of the body.
Gonadal veins
Testicles or ovaries drain.They drain into the inferior vena cava (right) or renal vein (left).
Peroneal nerve
Also called deep fibular nerve. It innervates muscles of the anterior compartment of the leg. It is key in the dorsiflexion of the foot. Its injury can cause "foot drop," where the foot does not lift when walking.
Oral cavity
Secondary airway for entry. Also involved in phonation and mouth breathing.
Axillary veins
Blood is drawn from the arm and axillary region.They continue as subclavian veins.
Artery femoral
Main artery of the thigh. It continues from the external iliac and becomes the popliteal.
Semitendinosus
Part of the hamstring group, it is located at the back of the thigh. It allows bending the knee and extending the hip. It is important for running, jumping, and maintaining posture.
Intercostal nerves
They are 11 pairs that originate from the thoracic nerves and are located between the ribs. They innervate the intercostal muscles and the skin of the thorax and abdomen. They participate in breathing by controlling the muscles that elevate and lower the ribs.
Portal vein
Blood drains from the liver to the inferior vena cava.They are essential for hepatic venous return.
Short extensorof the toes
This muscle on the back of the foot extends the toe joints, allowing them to lift and aiding in walking.
Clitoris
Highly sensitive external organ that is part of the female genital system and involved in sexual pleasure.
Clitoral glans
Visible external part of the clitoris with a high concentration of nerve endings.
Corpora cavernosa
Erectile structure of the clitoris that fills with blood during sexual arousal, increasing its size.
Spongy body
Tissue surrounding the female urethra that also contributes to clitoral erection.
Tibia
The tibia is one of the long bones of the leg, located at the front and medial side, between the knee and the ankle. It is the main bone that supports the body's weight when in contact with the femur and the foot. Thanks to its strength, the tibia allows movements such as walking, running, and jumping, and also protects the bone marrow inside. It also serves as an attachment point for important muscles that control the mobility of the leg and foot.
Nervous System
The Integrator
The nervous system links thought, sensation and movement via billions of neurons. It constantly samples internal and external environment and adjusts every other system accordingly.In physiology, signals travel clearly, attention focuses easily, and stress responses correlate with needs.
Fascinating FactEvery thought, emotion, and movement is powered by tiny electrical currents created when sodium, potassium, calcium, and chloride ions move through microscopic channels in your neurons. You literally think in electrolytes!
More detail on the nervous system
Sternum
The sternum is a flat, elongated bone located in the center of the chest. Connects the ribs through the costal cartilages and is part of the thoracic cage. Its main function is to protect vital organs such as the heart and lungs. Additionally, it serves as a point of attachment for muscles involved in breathing and trunk movement.
Pectoralis major
The pectoralis major is a large and superficial muscle of the chest. It is responsible for moving the arm toward the center of the body (adduction), rotating it internally, and lifting it. It is important in activities such as pushing or lifting objects.
Fallopian Tubes
They are ducts that connect the ovaries to the uterus and allow the passage of the egg. It is also the place where fertilization usually occurs.
Prostate gland
A fluid that protects and activates sperm, forming part of semen.
Anterior tibialis
Located at the front of the leg, this muscle is responsible for dorsiflexion of the foot (lifting the toes) and for maintaining balance while walking.
Dorsal digital arteries
Terminal branches of the dorsal metatarsals. Supply blood to the toes on their dorsal side.
Renal arteries
Originate from the abdominal aorta. Supply blood to the kidneys and adrenal glands.
Subclavian veins
Transport blood from the arms to the heart. Receive the internal jugular to form the superior vena cava.
Great saphenous vein
It is the longest superficial vein in the body.Drains blood from the foot to the femoral vein.
Acromion
The acromion is a bony extension of the scapula that forms the highest part of the shoulder. It connects to the clavicle via the acromioclavicular joint, providing stability to the area. This bone acts as an anchor point for important shoulder muscles and protects the rotator cuff tendons during arm movement.
Peroneuslongus
Located on the side of the leg, it allows foot eversion (turning outward) and assists in plantar flexion.
Thigh abductor
They are a group of muscles located on the lateral part of the hip, mainly the gluteus medius and minimus. They allow separating the thigh from the body and stabilizing the pelvis when walking or standing on one leg. They are key for balance and lateral mobility.
Sternocleidomastoid
The sternocleidomastoid is a long and superficial muscle of the neck that connects the sternum and clavicle to the mastoid process of the temporal bone. This muscle is responsible for rotation and lateral flexion of the head, as well as neck flexion forward. Thanks to its function, it allows essential movements for head orientation and breathing, being a key muscle for cervical mobility and posture.
Tonsils
The tonsils are organs of the lymphatic system located in the throat. They act as filters that trap viruses and bacteria that enter through the mouth or nose. They also produce white blood cells to fight infections.
Stomach
Muscular organ that mixes food with gastric juices, initiating protein digestion.
Bones of the tarsus
The bones of the tarsus form the back part of the foot, located between the tibia, fibula, and metatarsals. They are composed of seven bones that provide support and stability to the foot, as well as facilitate movement at the ankle joint. Thanks to their structure, the bones of the tarsus allow supporting the body's weight during activities such as walking and running, and help to absorb impact when stepping, protecting the joints and soft tissues of the foot.
Medial condyle
The medial condyle is a rounded prominence located on the inner lower part of the femur. Along with the lateral condyle, it forms part of the knee joint by articulating with the tibia and the patella. Thanks to its size and shape, it supports a greater load, especially on the inner part of the knee. Additionally, it facilitates flexion and extension movements, and contributes to joint stability.
Rectus femoris
It is part of the quadriceps and extends from the hip to the knee. It allows leg extension and hip flexion, being essential for walking, running, and jumping.
Bronchi lobar middle
Bronchi that ventilate the middle lobe of the right lung. They branch off from the main right bronchus.
Bonesphenoid
The sphenoid is a complex bone located in the center of the skull. Connects various skull bones and protects the pituitary gland.
Radial extensor of the wrist
This forearm muscle is divided into long and short. It allows extension and abduction (moving outward) the wrist. It is important for stabilizing the wrist during gripping or manual activities.
Femoral nerve
Originates in the lumbar plexus. Innervates the anterior thigh muscles (such as the quadriceps) and the skin of the anterior and medial thigh. Allows knee extension and hip flexion, being essential for walking and standing up.
Achilles tendon
It is not a muscle, but a very strong tendon that connects the muscles of the calf (gastrocnemius and soleus, to the heel bone (calcaneus). It is essential for walking, running, and jumping, as it allows plantar flexion of the foot.
Renal pelvis
It is the internal cavity where urine produced in the kidney is collected. From there, urine flows into the ureter to be transported. It functions as a connection between the nephrons and the urinary tracts.
Brachial vein
Blood is drawn from the arm and axillary region.They continue as subclavian veins.
Serratus anterior
The serratus anterior extends from the ribs to the scapula. Its function is to stabilize the scapula and allow its upward rotation. It is key to lifting the arm above the head.
Ulnar arteries
Terminal branch of the brachial nerve, located on the medial side of the forearm. Supplies muscles of the forearm and hand.
External jugular vein
Collect blood from the scalp and superficial face. Drains into the subclavian vein.
Tibial nerve
Also derived from the sciatic nerve. It innervates the posterior muscles of the leg and the sole of the foot. It is crucial for plantar flexion (standing on tiptoes) and the sensation of the sole of the foot.
Anus
Final opening of the digestive tract through which feces are expelled to the outside.
Right lung
Organ with three lobes responsible for gas exchange of oxygen and carbon dioxide. It is larger than the left.
Biceps femoris
Another hamstring muscle, with two heads (long and short). Flexes the knee and extends the hip. It also rotates the leg outward when the knee is flexed.
Seminal vesicle
Produce a nutrient-rich fluid that is part of semen and nourishes the sperm.
Phalanges
Phalanges are the bones that form the fingers of the hands and feet. Each finger has three phalanges —proximal, middle, and distal— except the thumb, which has two. These small bones allow flexion, extension, and other fine movements of the fingers, which are essential for activities like grasping, writing, or playing instruments. Additionally, the phalanges protect nerve endings and soft tissues at the fingertips.
Sartorius
The sartorius is the longest muscle in the human body. It crosses the thigh from the hip to the tibia and allows flexion, abduction, and external rotation of the hip, in addition to flexing the knee.
Great saphenous vein
Superficial vein running along the back of the leg. Drains into the popliteal vein.
Penis
External organ that allows penetration during intercourse and the expulsion of semen and urine.
Corpora cavernosa
Two columns of erectile tissue that allow the rigidity of the penis during an erection.
Gland
Tip of the penis, very sensitive, involved in sexual pleasure and protects the urethra.
Spongy body
Erectile tissue that surrounds the urethra and prevents its compression during erection.
Skull
The skull is the bony structure that protects the brain, one of the most important parts of the nervous system. It is made up of 22 bones, which articulate with each other and shape the head. In addition to protecting the brain, the skull supports the muscles of the face and houses the organs of the senses such as the eyes, ears, and nose.
Inner rectus (Gracilis)
It is a long and slender thigh muscle that participates in thigh adduction and the knee flexion. It is located on the medial part of the thigh.
Lymph nodes of the upper limbs
They are found along the arms and in the armpits. They filter lymph from the tissues of the hands, forearms, and arms.They are essential for detecting infections or injuries in the limbs.
Digestive System
The Gateway
The digestive tract is the gateway between the world and you. It welcomes, breaks down, and transforms food into energy and information. Its walls are lined with sensors, deciding what to let in and what to keep out. When it’s in balance, you feel grounded, nourished, and stable — your body trusts the world.
Fascinating FactThe barrier between “you” and “not you” is only one epithelial cell thick—thinner than cling film—yet it handles tons of antigens daily.Tight junctions and mucus make it a living fortress.
More information on the digestive system
Lumbar lymph nodes
They are located in the lower part of the abdomen, near the spine. They filter the lymph coming from the abdominal organs and pelvis. They are important in the immune response of the lower trunk region.
Peroneal veins
Located on the lateral side of the leg. Drain blood into the posterior tibial veins.
Temporal
The temporal bones are on the sides of the skull, near the ears. They contain structures of the ear and protect the brain laterally.
Inferior vena cava
Collect blood from the lower part of the body.Bring the blood to the right atrium of the heart.
Superficial peroneal nerve
Common fibular nerve branch. Innervates muscles that allow foot eversion and provides sensation to the dorsum of the foot. Injuries to this nerve can cause weakness when walking on uneven surfaces.
Bronchi lower lobes
Branches that lead air to the lower lobe of the lungs.They are essential for ventilating the lower part of the lung.
Paranasal Sinuses
Air-filled bony cavities surrounding the nose. They reduce skull weight, improve vocal resonance, and help humidify the air.
Dorsal metatarsal arteries
Located at the top of the foot. They irrigate the spaces between the metatarsals and the toes.
Ribs
The ribs are curved, flat bones that are part of the thoracic cage. In total, we have 24 ribs (12 pairs) that articulate with the vertebral column and mostly with the sternum. Its main function is to protect vital organs such as the heart and lungs, as well as participate in breathing by expanding and contracting the chest during inhalation and exhalation.
Biceps brachii
Located at the front part of the arm, the biceps has two heads (long and short) and allows for elbow flexion and forearm supination (turning the palm upward). It is very active in movements such as lifting weights.
Common extensor ofthe fingers
It is a muscle of the forearm that extends to the index, middle, ring, and little fingers. It allows these fingers and the wrist to extend. It is essential for opening the hand and performing movements such as releasing objects or typing.
Lateral condyle
The lateral condyle is one of the two rounded prominences located at the lower part of the femur. It articulates with the tibia and the patella, forming an essential part of the knee joint. Thanks to its shape and cartilage covering, it allows smooth and stable movement of the knee during flexion and extension. Additionally, it distributes the forces acting on the joint and protects internal structures.
Head of the humerus
The head of the humerus is the upper and rounded part of the arm bone, which articulates with the scapula at the shoulder joint. This spherical shape allows for a wide variety of arm movements in multiple directions. Thanks to its smooth surface and its fit in the glenoid cavity, it facilitates movements such as raising, rotating, and extending the arm. Additionally, it is key for shoulder stability along with muscles and ligaments.
Common fibular nerve
Sciatic nerve branch. It divides into fibular superficial and deep nerves, which innervate the leg and foot. Controls dorsiflexion of the foot (lifting the toes) and part of the sensation on the dorsum of the foot.
Pectineus
The pectineus is a short muscle located at the top of the thigh. It helps flex and abduct the hip, meaning it brings the leg closer to the body's midline.
Salivary glands
Produce saliva to initiate digestion and keep the mouth moist. They include the parotid, submandibular, and sublingual glands, and release enzymes like amylase that break down food.
Rectum
Temporarily stores stool until it is eliminated from the body through the anus.
Superior vena cava
Aorta artery
Pulmonary artery
Left atrium auricle
Heart
Right atrium auricle
Muscular organ that pumps blood throughout the body. It has four chambers: two atria and two ventricles.
Right ventricle
Left ventricle
Diaphragm
Main muscle of respiration. It contracts during inhalation and separates the thoracic cavity from the abdominal cavity.
Sacral plexus
Formed by spinal nerves L4 to S4. It innervates the pelvis, glutes, perineum, and lower limbs. The sacral plexus gives rise to the sciatic nerve, the longest and thickest nerve in the human body.
Musculocutaneous nerve
Branch of the brachial plexus. Innervates the flexor muscles of the arm (biceps, brachialis, and coracobrachialis) and the skin of the lateral forearm. Allows elbow flexion and provides tactile sensation on the outer part of the forearm
Vagina
Muscular tube that connects the uterus to the outside; allows menstruation, intercourse, and childbirth.
Nervous System
The Integrator
The nervous system links thought, sensation and movement via billions of neurons. It constantly samples internal and external environment and adjusts every other system accordingly.In physiology, signals travel clearly, attention focuses easily, and stress responses correlate with needs.
Fascinating FactEvery thought, emotion, and movement is powered by tiny electrical currents created when sodium, potassium, calcium, and chloride ions move through microscopic channels in your neurons. You literally think in electrolytes!
More detail on the nervous system
Female and male urethra
The female urethra is short and only transports urine. In men, it is longer and also expels semen. Both connect the bladder to the outside, completing the excretion process.
Male
Female
Upper jaw
The upper jaw forms the middle part of the face.Supports the upper teeth and participates in the formation of the nose and the palate.
Pharynx
Common duct to the digestive and respiratory system. It directs air from the nose or mouth to the larynx.
Endocrine System
The Timing Mechanism
Hormones secreted by glands such as the hypothalamus, pituitary, thyroid, adrenals, and gonads coordinate long-term adaptation. Through feedback loops, the endocrine system synchronises circadian rhythm, metabolism, growth, and fertility. Energy, mood, and reproduction align with the cycles of day, season, and life stage.
Your hormones are not just “chemical moods” — they’re broadcast signals of context. Every gland is asking, “What kind of world am I in, and how should this body behave?”In a moment of danger, the adrenal glands flood you with cortisol and adrenaline — gearing you for survival. In times of safety, the thyroid opens up metabolism, and sex hormones rise, inviting growth, curiosity, and connection.
More about the endocrine system
Vastus lateralis
Located on the outer part of the thigh, this muscle also belongs to the quadriceps and helps extend the knee.
Endocrine System
The Timing Mechanism
Hormones secreted by glands such as the hypothalamus, pituitary, thyroid, adrenals, and gonads coordinate long-term adaptation. Through feedback loops, the endocrine system synchronises circadian rhythm, metabolism, growth, and fertility. Energy, mood, and reproduction align with the cycles of day, season, and life stage.
Your hormones are not just “chemical moods” — they’re broadcast signals of context. Every gland is asking, “What kind of world am I in, and how should this body behave?”In a moment of danger, the adrenal glands flood you with cortisol and adrenaline — gearing you for survival. In times of safety, the thyroid opens up metabolism, and sex hormones rise, inviting growth, curiosity, and connection.
More about the endocrine system
Median nerve
Originates from the brachial plexus and passes through the carpal tunnel. Innervates muscles of the forearm and part of the hand. Allows wrist flexion and fingers, as well as the movement of the thumb. Compression causes carpal tunnel syndrome.
Axillary lymph nodes
They are located in the armpits and filter the lymph from the arm, chest, and upper abdomen. They are key in detecting infections or diseases such as breast cancer. They are usually examined in medical check-ups for their diagnostic value.
Central nervous system
The central nervous system controls vital functions and processes the body's information. It is composed of the brain and spinal cord. The brain interprets stimuli, coordinates thought, language, memory, and emotions. The spinal cord transmits signals between the brain and the rest of the body.
Myometrium
It is the muscular layer of the uterus, responsible for contractions during childbirth and menstruation.
Digital arteries
Fingers and toes itch. They originate from the palmar or dorsal arteries.
Head of the femur
The head of the femur is the spherical part and upper of the femur, the longest bone in the body. It fits into the acetabulum of the pelvis, forming the hip joint and allowing wide and stable movements. Thanks to its rounded shape and smooth surface covered with cartilage, it facilitates smooth sliding within the joint cavity.Additionally, it is key in the transmission of body weight from the pelvis to the legs.
Trachea
Tube that connects the larynx to the bronchi. It transports air to the lungs and is reinforced by cartilaginous rings.
Digestive System
The Gateway
The digestive tract is the gateway between the world and you. It welcomes, breaks down, and transforms food into energy and information. Its walls are lined with sensors, deciding what to let in and what to keep out. When it’s in balance, you feel grounded, nourished, and stable — your body trusts the world.
Fascinating FactThe barrier between “you” and “not you” is only one epithelial cell thick—thinner than cling film—yet it handles tons of antigens daily.Tight junctions and mucus make it a living fortress.
More information on the digestive system
Endometrium
Inner layer of the uterus that thickens during the menstrual cycleand detaches if there is no fertilization.
Vena cava
The vena cava is the largest blood vessel in the body. It collects oxygen-poor blood from throughout the body and carries it to the heart. It is made up of two parts: the superior and inferior vena cava.
Aorta artery
The aorta is the main artery that exits the heart. It distributes oxygen-rich blood to all organs and tissues of the body. Its branched structure allows it to irrigate from the head to the feet.
Systems
Anna Heslop
Created on November 6, 2025
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Transcript
Systems
Immune System
Musculo-skeletal System
Cardiovascular system
Endocrine System
Nervous System
Digestive System
Respiratory System
Lymphatic System
Integration System
Microbiome
Metabolic System
Physiology
Normal Biological Function
Environment
Hormetic stressors
Low toxic exposure
Proactive in maintaining health
Life has meaning and purpose
Feels safe
Whole-foods ancestral diet
Restorative rest and movement
Systems
Musculo-skeletal System
Nervous System
Light and nature exposure
Joyful movement
Endocrine System
Digestive System
Cardiovascular system
Respiratory System
Metabolic System
Immune System
Microbiome
Symptoms
Calm
Strong
Integration System
Lymphatic System
Relaxed
Flexible
Stable energy
Resilient
Clear vision
Reliable sleep
Flows through menstrual cycle / menopause with ease
Clear-headed
Smooth digestion
Able to overcome difficulties
Adaptable
Environment
Low toxic exposure
Life has meaning and purpose
Restorative rest and sleep
Whole-foods ancestral diet
Proactive in maintaining health
Feels safe
Light and nature exposure
Hormetic stressors
Joyful movement
Symptoms
Calm
Flexible
Stable energy
Resilient
Relaxed
Reliable sleep
Clear vision
Adaptable
Strong
Smooth digestion
Flows through menstrual cycles and menopause with ease
Clear-headed
Able to overcome difficulties
HumanBody Anatomy
Start
Human skeleton
Front part
The human skeleton is formed by more than 200 bones that provide support and protection to internal organs; and also enable movement through joint action with muscles. Its symmetrical structure helps us maintain balance and an upright posture.
+200
12%
of body weight
bones
Bones account for approximately 12% of total body weight. Although they are lightweight, they are extremely strong and durable.
The adult human body has 206 bones, organized into the axial skeleton (skull, spine, ribs) and the appendicular skeleton (limbs).
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Human skeleton
Back
The human skeleton viewed from the back includes fundamental bony structures such as the spine, scapulae, posterior ribs, pelvis, and limb bones. These parts work together to provide support, protect the spinal cord and internal organs, and enable body movement. The spine aligns from the base of the skull to the pelvis, while the scapulae and humerus allow arm movement. At the bottom, the sacrum, coccyx, and leg bones support the body upright and facilitate movement.
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Osteology of the skull
Bone structure and main functions
The skull is composed of a set of bones that protect the brain and form the facial structure. It is divided into two main parts: the neurocranium, which surrounds and protects the brain, and the viscerocranium, which shapes the facial structure. The neurocranium includes bones such as the frontal, parietal, temporal, occipital, sphenoid, and ethmoid. These bones are joined by sutures, which are immovable joints that allow controlled growth during childhood.
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Muscular System
The muscular system is essential for movement and stability of the body.
They are divided into skeletal, cardiac, and smooth muscles. Skeletal muscles enable voluntary movements, cardiac muscles control heartbeat, and smooth muscles regulate automatic internal functions:
+600
muscles work together to maintain posture, facilitate movement, and generate body heat.
Nervous system
Coordinates and regulates body functions throughelectrical and chemical impulses
The nervous system allows communication between the brain, spinal cord, and the rest of the body. It is composed of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves and ganglia), and controls both voluntary and automatic functions. It processes environmental stimuli, regulates internal organs, and is essential for activities such as thinking, movement, and emotions. Neurons are its main cells, transmitting signals via electrical impulses and neurotransmitters, ensuring quick and precise responses.
Digestive system
Set of organs responsible for transformingfood into nutrients for the body.
The digestive system processes food through mechanical and chemical digestion, absorbs nutrients, and eliminates waste. It begins in the mouth and ends at the anus, including organs such as the stomach, intestines, liver, pancreas, and gallbladder.
Stomach
Pancreas
Gallbladder
Produces digestive enzymes and hormones like insulin.
Stores and releases bile, a liquid that helps digest fats.
Mixes food with gastric juices to initiate protein digestion.
Respiratory system
The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. This process is essential for cellular respiration and energy production.
01.
Nasal cavities and nasal cavity
They filter, humidify, and warm the inspired air. Mucous membranes and hairs trap particles and microorganisms.
Pharynx and larynx
02.
The pharynx connects the respiratory tract with the esophagus. The larynx contains the vocal cords and allows air to pass into the trachea.
Trachea and bronchi
03.
The trachea is a reinforced tube with cartilaginous rings that divides into bronchi, which carry air to each lung.
Lungs and alveoli
04.
Lungs contain millions of alveoli, where gas exchange occurs: oxygen passes into the blood and CO₂ is eliminated.
Circulatory system
The circulatory system is responsible for transporting blood, oxygen, and nutrients throughout the body. It is composed of the heart, arteries, veins, and capillaries. Arteries carry oxygen-rich blood from the heart to the tissues, while veins return blood with carbon dioxide. This system is vital for organ function and maintaining the body's internal balance.
Veins
Arteries
Female reproductive system
Organs responsible for reproduction, gestation, and childbirth
The female reproductive system is made up of internal and external organs. Its main function is to enable fertilization, embryo development, and childbirth. Internal organs include ovaries, fallopian tubes, uterus, and vagina. External organs form the vulva, which protects the entrance to the reproductive system. In addition to its reproductive role, it also participates in the production of sex hormones such as estrogen and progesterone, which are essential in the menstrual cycle.
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Male reproductive system
Organs responsible for sperm and sex hormone production
The male reproductive system is made up of internal and external structures. Its main function is to produce, store, and transport sperm, as well as secrete testosterone.
Lymphatic system
Defense and balance in the human body
The lymphatic system is a network of vessels, lymph nodes, and organs that protects the body from infections and diseases. Its main function is to transport lymph, a clear fluid containing white blood cells, nutrients, and cellular waste. What does this system do?
What do we see here? The image shows a lymph node, where lymph is filtered. Inside, lymphocytes (a type of white blood cell) identify and attack harmful agents before they spread through the body.
Excretory system
The excretory system is responsible for removing waste from the body to maintain internal balance. Organs such as the kidneys, bladder, and skin work together to filter, transport, and expel substances that are no longer useful. Without this system, the body would accumulate toxins that could impair its functioning.
What is the function of the excretory system in the human body?
01.
Blood filtration
The kidneys filter the blood to remove waste such as urea and excess salts. This process produces urine, which will later be expelled from the body.
02.
Transport and storage
The ureters carry urine from the kidneys to the bladder, where it is stored temporarily. When necessary, urine is expelled through the urethra.
Elimination of toxins through other pathways
03.
In addition to urine, the body eliminates waste through sweat and breathing. The skin and lungs also participate in the excretion of unwanted substances.
Metatarsals
The metatarsals are five long bones that form the middle part of the foot, between the tarsal bones and the toe phalanges. They are essential for maintaining the arch of the foot and allow movements that facilitate walking and balance. Thanks to their arrangement, the metatarsals help to distribute body weight when walking, running, or jumping, and provide support for the musculature and ligaments of the foot.
Popliteal lymph nodes
They are behind the knees and filter the lymph from the feet, legs, and lower thighs. Although small, they serve an important role in local immune defense. Their inflammation can indicate infections or injuries in the legs or feet.
Latissimus dorsi
It is one of the largest muscles in the body. It covers the lower part of the back and inserts into the humerus. It participates in extension, adduction, and internal rotation of the arm. It is key in movements like rowing, swimming, or climbing.
65%
+178
automatic functions
water
The body is composed of about 65% water, a vital element for all cell functions and for maintaining a stable body temperature.
The human body performs over 178 automatic functions daily, such as breathing, blinking, or regulating body temperature, all without us realizing!
32%
+45
heartenergy
activedefenses
Approximately 32% of the energy produced by the body is allocated to keeping the heart and circulatory system functioning.
The immune system uses more than 45 types of cells to defend us from viruses, bacteria, and other external agents.
Frontal
The frontal bone forms the forehead and protects the frontal lobe of the brain. It is key for functions such as thinking and control of movement, as well as shaping the face.
Large intestine
Absorbs water and forms the stool from the undigested material in the small intestine.
Pulmonary veins
Carry oxygenated blood from the lungs to the heart. They flow into the left atrium.
Tibial arteries
Branches of the popliteal: anterior and posterior. They supply the anterior and posterior compartments of the leg.
Uterus
Hollow organ where the embryo develops during pregnancy; it is formed by the endometrium, myometrium, and perimetrium.
Pulmonary veins
Although they are veins, they carry oxygenated blood. They carry blood from the lungs to the left atrium of the heart.
Immune System
Surveillance, Communication, and Repair
Fascinating FactThe body naturally allows the presence of some self-reactive B-cells and T-cells. This is part of normal function because there are invadors and cancerous cells that we want to be protected against. The immune system has several mechanisms in place to make sure that these self-reactive cells stay on task and keep the peace.
This distributed network of cells, tissues, and signalling molecules is responsible for identifying, neutralising, and removing threats while maintaining the integrity of the body’s own tissues. It functions through a balance of activation and regulation rather than constant defence. Immune activity is continuously shaped by the nervous system, the endocrine system, and the metabolic state of each cell. The immune system therefore acts as both sensor and effector—interpreting information from the environment, microbiome, and internal milieu, and translating it into tissue repair or defence.
More information on the immune system
Main bronchi
Two ducts that originate from the trachea and lead to each lung. They are the main airways to the lungs.
Spinal column
The spine is a central bony structure that runs from the base of the skull to the pelvis. It is made up of 33 vertebrae grouped into five regions: cervical, thoracic, lumbar, sacral, and coccygeal. Its main function is to protect the spinal cord and support the body. Thanks to its natural curves and intervertebral discs, it allows flexibility, impact absorption, and movements such as bending, twisting, and standing upright.
Humerus
The humerus is the long bone of the arm that extends from the shoulder to the elbow. It articulates with the scapula at its upper end and with the radius and ulna at the lower end. It is essential for arm movements, as it supports muscles that allow lifting, rotating, and flexing. It also protects important nerves that pass through this area.
Internal carotid arteries
They originate from the common carotids and penetrate the skull. They irrigate the anterior brain and ocular structures.
Cephalic vein
Drain the lateral part of the arm and forearm.Connects to the axillary vein near the shoulder.
Phalanges
The phalanges are the bones that form the toes. Each of them has three phalanges —proximal, middle, and distal— except for the big toe, which only has two. These small bony structures allow movement of flexion and extension that are fundamental to maintain balance and the stability when walking or running. Additionally, they protect nerve endings and soft tissues at the tips of the toes.
Inguinal lymph nodes
They are located in the groin and filter lymph from the legs, feet, and pelvic region. They often become inflamed due to infections or wounds in the lower limbs. They are key in detecting problems in the lower part of the body.
Ulnar nerve
Branch of the brachial plexus. It runs through the arm to the hand, where it innervates the little finger and ring finger, as well as intrinsic muscles of the hand. It is responsible for fine motor skills and often causes the sensation of “electric shock” when hitting the elbow (nerve of the “little bone”).
Popliteal arteries
Located behind the knee. Irrigates the posterior region of the knee and the leg.
Superficial flexor ofthe fingers
This muscle flexes the middle joints of the fingers, allowing them to bend partially. It is essential for grip function in the hand.
Deep femoral vein
Collect blood from the deep muscles of the thigh. It joins the main femoral.
Iliac veins
Blood is drawn from the lower limbs and pelvis. They form the inferior vena cava when they join.
Gluteus maximus
It is the largest and most superficial muscle of the glutes. It is responsible for extending and rotating externally the hip. It is essential for standing up, climbing stairs, and running. It also shapes and adds volume to the gluteal region.
Ilium
The ilium is the largest and uppermost part of the hip bone, located in the pelvis, above the pubis and the ischium. It is responsible for supporting the body's weight in an upright position and connects to the spine through the sacroiliac joint. Thanks to its broad and curved shape, the ilium provides attachment for numerous muscles of the trunk and lower limbs. Additionally, its structure helps to protect internal organs such as the intestines and part of the reproductive system.
Rhomboid Muscle
Located between the shoulder blades and the spine, the rhomboid muscle (major and minor) retracts the scapula, bringing it closer to the spine. It also contributes to its elevation and rotation. It is essential for maintaining a good posture and shoulder stability.
Liver
Organ that produces bile, processes nutrients, and detoxifies harmful substances in the body.
Inner vastus (Vastus medialis)
This muscle is located on the inner part of the thigh. Its function is to extend the leg at the knee joint and to stabilize the kneecap.
Peronealarteries
Posterior tibial branch. Irrigates the lateral compartment of the leg.
Basilic vein
Located in the medial part of the arm.Connects to the brachial to form the axillary vein.
Popliteal vein
Located behind the knee. Collects blood from the leg and drains into the femoral vein.
Thymus
It is an organ located behind the sternum, activemainly in childhood. There, T lymphocytes mature, which are essential for the immune system. Over time, the thymus decreases in size and activity.
Upper lobar bronchi
Branches that carry air to the upper lobe of both lungs. They branch from the main bronchi.
Gluteus medius
Located on the side of the hip. Its main function is the thigh abduction (separating the leg from the body) and the pelvic stabilization during walking or when standing on one leg.
Nasal cavity
Structure that filters, warms, and humidifies the air we breathe. It is the main entry point of the respiratory system
Trapezius
The trapezius muscles are large and triangular muscles located at the top of the back and neck. Their main function is to move, elevate, and stabilize the scapula, as well as extend and rotate the neck. They are essential for movements of the shoulder and the head.
Basilar artery
It is formed by the union of the two vertebral arteries. It supplies the brainstem, cerebellum, and part of the posterior brain.
Internal jugular vein
Drains blood from the brain, face, and neck. It joins the subclavian vein to form the brachiocephalic vein.
Soleus
Located beneath the gastrocnemius in the calf, the soleus allows plantar flexion (pushing the foot downward) and is crucial for standing and walking.
Radial artery
Another branch of the brachial artery is located on the lateral part of the forearm. Important in hand irrigation and radial pulse measurement
Metacarpals
The metacarpals are a group of five long bones located in the hand, between the wrists and the fingers. They form the central structure of the palm and enable the necessary movement and stability to perform precise movements with the hand. Thanks to their joint with the carpal bones and the phalanges, the metacarpals facilitate actions such as grabbing, holding, and manipulating objects. Additionally, they provide support and protection to the nerves and blood vessels that pass through the hand.
Lower jaw
The lower jaw, or mandible, is the movable bone of the face. It allows chewing and forms the lower structure of the face.
Vertebral arteries
They originate from the subclavian arteries and ascend through the cervical vertebrae. They supply blood to the posterior brain, spinal cord, and cerebellum.
Appendix
Although its function is debated, the appendix contains lymphatic tissue. It is believed to contribute to the immune system in early stages of life. It can become inflamed, causing appendicitis, a common medical emergency.
Ulna
The ulna is one of the two bones of the forearm, located on the pinky side. It extends from the elbow to the wrist and works together with the radius to allow arm movement and forearm stability. At its upper end, it forms part of the elbow joint, and at the lower end, it connects with the wrist bones. It is essential for the movements of extension and flexion of the arm.
External carotid arteries
Superficial structures of the head, face, and neck are irritated. They have multiple branches that supply muscles, glands, and skin.
Atlas
The atlas is the first cervical vertebra of the spine, located just below the skull. Its main function is to support the head and allow movements such as nodding. Unlike other vertebrae, the atlas has no vertebral body, giving it a ring-shaped and lightweight form. Together with the axis (second cervical vertebra), it forms a joint that facilitates neck mobility.
Sciatic nerve
The longest nerve in the body originates from the sacral plexus. It descends through the leg and innervates the posterior thigh muscles and the entire leg. Compression or irritation of the sciatic nerve causes pain that radiates from the lower back to the foot (sciatica).
Femoral vein
Transporta sangre desde la pierna al abdomen. Se convierte en la ilíaca externa al pasar por la ingle.
Common carotid arteries
Located on both sides of the neck. They bifurcate into the internal and external carotid at the level of the larynx.
Palmar longus
Thin muscle of the forearm, absent in some people. Assists in flexion of the wrist and in tensioning the palmar aponeurosis (palm tissue).
Pancreas
Secretes digestive enzymes into the small intestine and hormones like insulin into the blood.
Esophagus
Muscular tube that transports food from the pharynx to the stomach through peristaltic movements.
Iliac arteries
Arise from the bifurcation of the abdominal aorta. They irrigate the pelvis and lower limbs.
Median cubital vein
Connect the basilic and cephalic veins at the elbow.It is commonly used for blood withdrawal.
In turn, the viscerocranium is composed of bones such as the maxilla, mandible, nasal, zygomatic and others, which shape the face and house structures like the eyes, nose, and mouth. Additionally, the skull has openings called foramina, through which nerves and blood vessels pass, essential for brain and sensory functions. Thanks to its complex structure, the skull not only protects the central nervous system, but also serves as support for muscles that enable mastication and facial expression, being fundamental for daily life.
Gastrocnemius
This muscle forms the most visible part of the calf. It aids in the plantar flexion of the foot and also contributes to flexing the knee.
Dorsal metatarsal venous arch
Venous redness on the top of the foot.Drains into the saphenous veins.
Talus
The talus is a bone of the tarsus located between the tibia, fibula, and calcaneus. It is fundamental for the ankle joint and allows movements such as flexion and extension of the foot. Thanks to its strategic position, the talus transmits the body's weight from the leg to the foot and contributes to stability and mobility during walking.
Calcaneus
The calcaneus is the largest bone in the foot and forms the heel. It is located at the back of the tarsus and articulates with the talus and the cuboid, participating in the formation of the ankle and the arch of the foot. Thanks to its robust structure, it supports the body's weight when walking, running, or standing. Additionally, it serves as an insertion point for the Achilles tendon, enabling the movement of the foot downward.
Occipital
The occipital bone is located at the back and bottom of the skull and protects the occipital lobe of the brain. It is essential for functions such as vision and balance, in addition to connecting the skull with the spine.
Teres major
Located below the lesser tubercle, this muscle connects the scapula with the humerus. It allows extension, adduction, and internal rotation of the arm. It supports the latissimus dorsi in pulling movements.
Ureter
It is a thin tube that connects each kidney to the bladder. It transports urine through muscle contractions called peristalsis. Each person has two ureters, one for each kidney.
Parietal
The parietal bones form the upper and lateral part of the skull. They protect the brain and participate in the structure of the skull, providing support and shape.
Radial nerve
Posterior branch of the brachial plexus. It innervates the extensor muscles of the arm, forearm, and wrist, and provides sensation to the back of the hand. It is essential for extending the elbow, wrist, and fingers, and it is frequently affected in compression injuries.
Kidney
The kidneys filter the blood to remove waste and excess fluids. They convert these wastes into urine, which is then excreted. They also help control blood pressure and the body's chemical balance.
Shoulder blades
The scapulae, also known as shoulder blades, are two flat and triangular bones located on the back of the thorax. They articulate with the humerus and clavicle, forming a key part of the shoulder joint. Thanks to their shape and mobility, they allow a wide range of arm movements and serve as an anchor point for various muscles. Additionally, they contribute to the stability and flexibility of the shoulder girdle.
Vas deferens
It is a tube that transports sperm from the epididymis to the ejaculatory duct. It functions during ejaculation through muscular contractions.
Oblique
Located on the sides of the abdomen, this muscle allows rotation and lateral flexion of the trunk. It also helps with compression of the abdomen and breathing control.
Segmental bronchi
Branches of the lobar bronchi that carry air to specific lung segments.
Brachioradialis
The brachioradialis is a muscle of the forearm that allows elbow flexion, especially when the forearm is in a neutral position (such as when lifting a bottle). It is visible on the outer part of the forearm.
Radial flexorof the wrist
This forearm muscle allows flexion and deviation of the wrist toward the thumb side. It is important in precise hand movements such as writing or gripping small objects.
Bladder and urethra
The bladder stores urine until it is expelled. The urethra transports both urine and semen outside the body.
Ovaries
Glands that produce eggs and sex hormones such as estrogen and progesterone.
Axillary arteries
Continuation of the subclavian arteries in the axilla. They irrigate the upper part of the thorax, shoulder, and proximal arm.
Celiac trunk
First branch of the abdominal aorta. Supplies the stomach, liver, spleen, and part of the pancreas.
Kneecap
The kneecap, also known as patella, is a small bone located at the front of the knee. It functions as a shield that protects the joint and improves the efficiency of the quadriceps muscle by extending the leg. Thanks to its position, the kneecap facilitates knee movement and helps to distribute pressure during activities such as walking, running, and jumping, contributing to leg stability.
Lumbar column
The lumbar column is made up of 5 large and robust vertebrae, located in the lower back. These vertebrae support most of the body weight and allow movements such as bending or twisting the torso. They also protect the lower end of the spinal cord and serve as an anchor for muscles that stabilize the trunk and help us stand upright.
Pubic symphysis
The pubic symphysis is a cartilaginous joint that connects the two pubic bones at the front of the pelvis. It is composed of a cartilaginous disc that provides stability but also some flexibility. Its main function is absorbing impacts and allowing slight pelvic mobility, especially important during pregnancy and childbirth. It also contributes to body stability when walking or standing.
Lumbricals
The lumbricals are small muscles of the hand, located between the tendons of the deep flexor muscles of the fingers. They are responsible for flexing the metacarpophalangeal joints and extending the interphalangeal joints, facilitating fine finger movements. Thanks to their coordinated action, the lumbricals allow precise gestures such as writing or playing an instrument.
Lymph nodesof the thorax
They filter lymph from the lungs, heart, and other thoracic structures. They participate in protection against respiratory infections. They are also evaluated in diseases such as tuberculosis or cancer.
Fibula
The fibula is a long, slender bone located alongside the tibia, on the lateral side of the leg. Although it does not bear much of the body's weight, it is essential for ankle stability and leg mobility. Thanks to its location, the fibula provides attachment points for muscles and ligaments, contributing to balance and flexion of the foot. Additionally, it protects nearby nerve and vascular structures.
Gonadal arteries
They occur in the testes in men and the ovaries in women. They originate from the abdominal aorta.
Small intestine
Absorbs most nutrients thanks to its large surface area formed by intestinal villi.
Lumbar plexus
It originates from the nerve roots L1 to L4. It innervates the abdomen, pelvis, and front part of the thigh. Key nerves such as the femoral and obturator nerves come from it, which control muscles for walking and standing.
Saphenous nerve
It is a sensory branch of the femoral nerve. It runs along the inner part of the leg and foot. Its function is exclusively sensory, providing sensation to the medial surface of the leg and ankle.
Left lung
Respiratory organ composed of two lobes. It exchanges gases with less volume than the right one.
Brachial plexus
Nerve network that originates in the spinal cord, from the roots C5 to T1. It supplies shoulder, arm, forearm, and hand. It is essential for the movements and sensation of the upper limbs. Important nerves such as the radial, ulnar, and median nerves branch from it.
Digital veins
They bleed from the fingers of the hands and feet.Connect to dorsal and palmar venous networks.
Renal veins
Drain blood from the kidneys. They drain directly into the inferior vena cava.
Cervical lymph nodes
They are located in the neck and filter the lymph coming from the head and the upper neck region. They help detect and fight infections such as colds or tonsillitis. They tend to swell when the body responds to an infection.
Femur
The femur is the longest and strongest bone in the human body. It is located in the thigh, connecting the hip to the knee and supporting much of the body's weight. Thanks to its sturdy structure, the femur allows movements such as walking, running, and jumping. Additionally, it protects the bone marrow and provides attachment points for important muscles that control leg mobility.
Carpal bones
The carpal is made up of 8 small bones arranged in two rows, which form the base of the hand. These bones articulate with the radius, ulna, and metacarpals, allowing wrist mobility. Thanks to their shape and arrangement, the bones of the carpal provide flexibility and strength, facilitating movements such as rotating, bending, or extending the hand with precision.
Deltoid
The deltoid covers the shoulder and is divided into three portions: anterior, middle, and posterior. It allows lifting the arm forward, to the side, and backward, being essential in the arm abduction. It also contributes to the rounded shape of the shoulder.
Nasal bone
The nasal bones form the bridge of the nose. They serve as support for the nasal structure and protect the upper respiratory tracts.
Immune System
Surveillance, Communication, and Repair
Fascinating FactThe body naturally allows the presence of some self-reactive B-cells and T-cells. This is part of normal function because there are invadors and cancerous cells that we want to be protected against. The immune system has several mechanisms in place to make sure that these self-reactive cells stay on task and keep the peace.
This distributed network of cells, tissues, and signalling molecules is responsible for identifying, neutralising, and removing threats while maintaining the integrity of the body’s own tissues. It functions through a balance of activation and regulation rather than constant defence. Immune activity is continuously shaped by the nervous system, the endocrine system, and the metabolic state of each cell. The immune system therefore acts as both sensor and effector—interpreting information from the environment, microbiome, and internal milieu, and translating it into tissue repair or defence.
More information on the immune system
Larynx
Contains the vocal cords and regulates the airflow to the trachea. Participates in voice production.
Sacrum
The sacrum is a triangular bone formed by the fusion of five vertebrae located at the base of the spine. It is situated between the two parts of the pelvis bone and connects the spine with the hip bone. It acts as a support point for the upper part of the body and distributes weight to the legs. Additionally, it protects important nerves that extend toward the lower part of the body.
Clavicle
The clavicle is a long and slender bone that connects the sternum with the scapula. It is located at the top of the chest and is visible and palpable just below the neck. Its main function is to keep the arm separated from the trunk, allowing greater shoulder mobility and acting as support for the neck and shoulder muscles.
Sacral spinal nerves
They are five pairs (S1 to S5) emerging from the sacrum. They control motor and sensory functions of the pelvis and lower limbs. They also participate in sphincter control and in the sensitivity of the perineal region.
Testicle
Sperm and testosterone-producing organ, located inside the scrotum.
Intercostal muscles
These muscles are located between the ribs and are divided into external and internal. They participate in breathing: the external muscles help expand the chest during inhalation, and the internal muscles help reduce it during exhalation.
Triceps brachii
Located at the back of the arm, it has three heads (long, lateral, and medial). Its main function is to extend the elbow. It also participates in shoulder extension when the long head is activated.
Cervix
Also called the cervix, it is the lower part of the uterus that connects to the vagina and regulates the passage of sperm and menstrual flow.
Dorsal digital veins
Blood drains from the toes. They connect to the dorsal venous arch.
Aorta
It is the main artery of the body. It carries oxygen-rich blood from the heart to the entire body.
Pharynx
Muscular tube connecting the mouth to the esophagus and directing food toward the digestive system.
Acetabulum
The acetabulum is a cup-shaped cavity located in the pelvic bone. It is part of the hip joint as it receives the head of the femur, allowing leg movement in various directions. Thanks to its deep shape and reinforced by a ring of cartilage called labrum, it provides stability to the joint. Additionally, it distributes body weight from the pelvis to the lower limbs.
Superior vena cava
Carries deoxygenated blood from the upper part of the body to the heart. Drains into the right atrium.
Deep femoral arteries
Important branch of the femoral artery. Supplies deep muscles of the thigh.
Tensor of the fascia lata
This muscle is located on the lateral part of the hip and acts by tightening the fascia lata (tissue that surrounds the thigh muscles). It contributes to stabilization of the knee and hip during walking.
Mammary gland
The mammary gland is a set of glandular structures in the chest tissue. Its main function is the production and secretion of breast milk during breastfeeding. It is present in both women and men, although less developed in the latter.
Pubis
The pubis is one of the three parts that make up the hip bone, located at the front of the pelvis. Both sides of the pubis meet in the center through an joint called pubic symphysis. This bone supports the lower abdominal organs and is key in the structure of the pelvic floor. It also plays an important role in posture and body balance.
Subclavian arteries
Supply blood to the arms, neck, and part of the brain. Give rise to the vertebral and axillary arteries.
Brachial arteries
Prolongation of the axillary artery in the arm.It irrigates the muscles and tissues of the arm and divides into radial and ulnar.
Internal iliac veins
Blood drains from the pelvic organs. They join the external iliacs to form the common iliacs.
Liver
Organ that produces bile, processes nutrients, and detoxifies harmful substances in the body.
Spleen
It is the largest lymphatic organ and is located in the abdomen, near the stomach. Filters blood, removes old cells, and stores white blood cells. Helps fight infections and maintain blood balance.
Bladder
It is a hollow organ that stores urine before it is expelled. It expands and contracts depending on the amount of urine it contains. When it fills, it sends signals to the brain to initiate urination.
Semimembranosus
It is the deepest of the hamstrings. It helps to bend the knee, extend the hip, and rotate the leg internally. Along with the semitendinosus and the biceps femoris, it stabilizes the pelvis.
Lesser tubercle
The lesser tubercle is a small muscle of the rotator cuff. It originates from the scapula and inserts into the humerus. Its main function is externally rotating the arm and stabilizing the shoulder joint.
Suprahepatic veins
They drain blood from the liver into the inferior vena cava.They are essential for hepatic venous return.
Ulnar extensor of the wrist
Located on the back of the forearm, this muscle allows to extend and adduct (move inward) the wrist. It contributes to hand stability and is important in pushing movements.
Rectus abdominis
This muscle is located in the front part of the abdomen and is responsible for flexing the spine, maintaining posture, and containing the internal organs. It is part of the group known as “core”.
Tibial veins
Drain blood from the anterior and posterior regions of the leg. They join the popliteal vein.
Radius
The radius is one of the two bones of the forearm, located on the thumb side. It extends from the elbow to the wrist and works together with the ulna to allow arm movement and hand rotation. Thanks to the radius, we can turn the palm upward or downward, and perform precision movements essential in daily activities.
Cervical column
The cervical column is made up of the first 7 vertebrae of the spine. It is located in the neck and is responsible for supporting the skull and allowing head movement. Thanks to its flexibility, we can rotate, tilt, and extend the neck. Additionally, it protects the spinal cord as it travels toward the rest of the body.
Gonadal veins
Testicles or ovaries drain.They drain into the inferior vena cava (right) or renal vein (left).
Peroneal nerve
Also called deep fibular nerve. It innervates muscles of the anterior compartment of the leg. It is key in the dorsiflexion of the foot. Its injury can cause "foot drop," where the foot does not lift when walking.
Oral cavity
Secondary airway for entry. Also involved in phonation and mouth breathing.
Axillary veins
Blood is drawn from the arm and axillary region.They continue as subclavian veins.
Artery femoral
Main artery of the thigh. It continues from the external iliac and becomes the popliteal.
Semitendinosus
Part of the hamstring group, it is located at the back of the thigh. It allows bending the knee and extending the hip. It is important for running, jumping, and maintaining posture.
Intercostal nerves
They are 11 pairs that originate from the thoracic nerves and are located between the ribs. They innervate the intercostal muscles and the skin of the thorax and abdomen. They participate in breathing by controlling the muscles that elevate and lower the ribs.
Portal vein
Blood drains from the liver to the inferior vena cava.They are essential for hepatic venous return.
Short extensorof the toes
This muscle on the back of the foot extends the toe joints, allowing them to lift and aiding in walking.
Clitoris
Highly sensitive external organ that is part of the female genital system and involved in sexual pleasure.
Clitoral glans
Visible external part of the clitoris with a high concentration of nerve endings.
Corpora cavernosa
Erectile structure of the clitoris that fills with blood during sexual arousal, increasing its size.
Spongy body
Tissue surrounding the female urethra that also contributes to clitoral erection.
Tibia
The tibia is one of the long bones of the leg, located at the front and medial side, between the knee and the ankle. It is the main bone that supports the body's weight when in contact with the femur and the foot. Thanks to its strength, the tibia allows movements such as walking, running, and jumping, and also protects the bone marrow inside. It also serves as an attachment point for important muscles that control the mobility of the leg and foot.
Nervous System
The Integrator
The nervous system links thought, sensation and movement via billions of neurons. It constantly samples internal and external environment and adjusts every other system accordingly.In physiology, signals travel clearly, attention focuses easily, and stress responses correlate with needs.
Fascinating FactEvery thought, emotion, and movement is powered by tiny electrical currents created when sodium, potassium, calcium, and chloride ions move through microscopic channels in your neurons. You literally think in electrolytes!
More detail on the nervous system
Sternum
The sternum is a flat, elongated bone located in the center of the chest. Connects the ribs through the costal cartilages and is part of the thoracic cage. Its main function is to protect vital organs such as the heart and lungs. Additionally, it serves as a point of attachment for muscles involved in breathing and trunk movement.
Pectoralis major
The pectoralis major is a large and superficial muscle of the chest. It is responsible for moving the arm toward the center of the body (adduction), rotating it internally, and lifting it. It is important in activities such as pushing or lifting objects.
Fallopian Tubes
They are ducts that connect the ovaries to the uterus and allow the passage of the egg. It is also the place where fertilization usually occurs.
Prostate gland
A fluid that protects and activates sperm, forming part of semen.
Anterior tibialis
Located at the front of the leg, this muscle is responsible for dorsiflexion of the foot (lifting the toes) and for maintaining balance while walking.
Dorsal digital arteries
Terminal branches of the dorsal metatarsals. Supply blood to the toes on their dorsal side.
Renal arteries
Originate from the abdominal aorta. Supply blood to the kidneys and adrenal glands.
Subclavian veins
Transport blood from the arms to the heart. Receive the internal jugular to form the superior vena cava.
Great saphenous vein
It is the longest superficial vein in the body.Drains blood from the foot to the femoral vein.
Acromion
The acromion is a bony extension of the scapula that forms the highest part of the shoulder. It connects to the clavicle via the acromioclavicular joint, providing stability to the area. This bone acts as an anchor point for important shoulder muscles and protects the rotator cuff tendons during arm movement.
Peroneuslongus
Located on the side of the leg, it allows foot eversion (turning outward) and assists in plantar flexion.
Thigh abductor
They are a group of muscles located on the lateral part of the hip, mainly the gluteus medius and minimus. They allow separating the thigh from the body and stabilizing the pelvis when walking or standing on one leg. They are key for balance and lateral mobility.
Sternocleidomastoid
The sternocleidomastoid is a long and superficial muscle of the neck that connects the sternum and clavicle to the mastoid process of the temporal bone. This muscle is responsible for rotation and lateral flexion of the head, as well as neck flexion forward. Thanks to its function, it allows essential movements for head orientation and breathing, being a key muscle for cervical mobility and posture.
Tonsils
The tonsils are organs of the lymphatic system located in the throat. They act as filters that trap viruses and bacteria that enter through the mouth or nose. They also produce white blood cells to fight infections.
Stomach
Muscular organ that mixes food with gastric juices, initiating protein digestion.
Bones of the tarsus
The bones of the tarsus form the back part of the foot, located between the tibia, fibula, and metatarsals. They are composed of seven bones that provide support and stability to the foot, as well as facilitate movement at the ankle joint. Thanks to their structure, the bones of the tarsus allow supporting the body's weight during activities such as walking and running, and help to absorb impact when stepping, protecting the joints and soft tissues of the foot.
Medial condyle
The medial condyle is a rounded prominence located on the inner lower part of the femur. Along with the lateral condyle, it forms part of the knee joint by articulating with the tibia and the patella. Thanks to its size and shape, it supports a greater load, especially on the inner part of the knee. Additionally, it facilitates flexion and extension movements, and contributes to joint stability.
Rectus femoris
It is part of the quadriceps and extends from the hip to the knee. It allows leg extension and hip flexion, being essential for walking, running, and jumping.
Bronchi lobar middle
Bronchi that ventilate the middle lobe of the right lung. They branch off from the main right bronchus.
Bonesphenoid
The sphenoid is a complex bone located in the center of the skull. Connects various skull bones and protects the pituitary gland.
Radial extensor of the wrist
This forearm muscle is divided into long and short. It allows extension and abduction (moving outward) the wrist. It is important for stabilizing the wrist during gripping or manual activities.
Femoral nerve
Originates in the lumbar plexus. Innervates the anterior thigh muscles (such as the quadriceps) and the skin of the anterior and medial thigh. Allows knee extension and hip flexion, being essential for walking and standing up.
Achilles tendon
It is not a muscle, but a very strong tendon that connects the muscles of the calf (gastrocnemius and soleus, to the heel bone (calcaneus). It is essential for walking, running, and jumping, as it allows plantar flexion of the foot.
Renal pelvis
It is the internal cavity where urine produced in the kidney is collected. From there, urine flows into the ureter to be transported. It functions as a connection between the nephrons and the urinary tracts.
Brachial vein
Blood is drawn from the arm and axillary region.They continue as subclavian veins.
Serratus anterior
The serratus anterior extends from the ribs to the scapula. Its function is to stabilize the scapula and allow its upward rotation. It is key to lifting the arm above the head.
Ulnar arteries
Terminal branch of the brachial nerve, located on the medial side of the forearm. Supplies muscles of the forearm and hand.
External jugular vein
Collect blood from the scalp and superficial face. Drains into the subclavian vein.
Tibial nerve
Also derived from the sciatic nerve. It innervates the posterior muscles of the leg and the sole of the foot. It is crucial for plantar flexion (standing on tiptoes) and the sensation of the sole of the foot.
Anus
Final opening of the digestive tract through which feces are expelled to the outside.
Right lung
Organ with three lobes responsible for gas exchange of oxygen and carbon dioxide. It is larger than the left.
Biceps femoris
Another hamstring muscle, with two heads (long and short). Flexes the knee and extends the hip. It also rotates the leg outward when the knee is flexed.
Seminal vesicle
Produce a nutrient-rich fluid that is part of semen and nourishes the sperm.
Phalanges
Phalanges are the bones that form the fingers of the hands and feet. Each finger has three phalanges —proximal, middle, and distal— except the thumb, which has two. These small bones allow flexion, extension, and other fine movements of the fingers, which are essential for activities like grasping, writing, or playing instruments. Additionally, the phalanges protect nerve endings and soft tissues at the fingertips.
Sartorius
The sartorius is the longest muscle in the human body. It crosses the thigh from the hip to the tibia and allows flexion, abduction, and external rotation of the hip, in addition to flexing the knee.
Great saphenous vein
Superficial vein running along the back of the leg. Drains into the popliteal vein.
Penis
External organ that allows penetration during intercourse and the expulsion of semen and urine.
Corpora cavernosa
Two columns of erectile tissue that allow the rigidity of the penis during an erection.
Gland
Tip of the penis, very sensitive, involved in sexual pleasure and protects the urethra.
Spongy body
Erectile tissue that surrounds the urethra and prevents its compression during erection.
Skull
The skull is the bony structure that protects the brain, one of the most important parts of the nervous system. It is made up of 22 bones, which articulate with each other and shape the head. In addition to protecting the brain, the skull supports the muscles of the face and houses the organs of the senses such as the eyes, ears, and nose.
Inner rectus (Gracilis)
It is a long and slender thigh muscle that participates in thigh adduction and the knee flexion. It is located on the medial part of the thigh.
Lymph nodes of the upper limbs
They are found along the arms and in the armpits. They filter lymph from the tissues of the hands, forearms, and arms.They are essential for detecting infections or injuries in the limbs.
Digestive System
The Gateway
The digestive tract is the gateway between the world and you. It welcomes, breaks down, and transforms food into energy and information. Its walls are lined with sensors, deciding what to let in and what to keep out. When it’s in balance, you feel grounded, nourished, and stable — your body trusts the world.
Fascinating FactThe barrier between “you” and “not you” is only one epithelial cell thick—thinner than cling film—yet it handles tons of antigens daily.Tight junctions and mucus make it a living fortress.
More information on the digestive system
Lumbar lymph nodes
They are located in the lower part of the abdomen, near the spine. They filter the lymph coming from the abdominal organs and pelvis. They are important in the immune response of the lower trunk region.
Peroneal veins
Located on the lateral side of the leg. Drain blood into the posterior tibial veins.
Temporal
The temporal bones are on the sides of the skull, near the ears. They contain structures of the ear and protect the brain laterally.
Inferior vena cava
Collect blood from the lower part of the body.Bring the blood to the right atrium of the heart.
Superficial peroneal nerve
Common fibular nerve branch. Innervates muscles that allow foot eversion and provides sensation to the dorsum of the foot. Injuries to this nerve can cause weakness when walking on uneven surfaces.
Bronchi lower lobes
Branches that lead air to the lower lobe of the lungs.They are essential for ventilating the lower part of the lung.
Paranasal Sinuses
Air-filled bony cavities surrounding the nose. They reduce skull weight, improve vocal resonance, and help humidify the air.
Dorsal metatarsal arteries
Located at the top of the foot. They irrigate the spaces between the metatarsals and the toes.
Ribs
The ribs are curved, flat bones that are part of the thoracic cage. In total, we have 24 ribs (12 pairs) that articulate with the vertebral column and mostly with the sternum. Its main function is to protect vital organs such as the heart and lungs, as well as participate in breathing by expanding and contracting the chest during inhalation and exhalation.
Biceps brachii
Located at the front part of the arm, the biceps has two heads (long and short) and allows for elbow flexion and forearm supination (turning the palm upward). It is very active in movements such as lifting weights.
Common extensor ofthe fingers
It is a muscle of the forearm that extends to the index, middle, ring, and little fingers. It allows these fingers and the wrist to extend. It is essential for opening the hand and performing movements such as releasing objects or typing.
Lateral condyle
The lateral condyle is one of the two rounded prominences located at the lower part of the femur. It articulates with the tibia and the patella, forming an essential part of the knee joint. Thanks to its shape and cartilage covering, it allows smooth and stable movement of the knee during flexion and extension. Additionally, it distributes the forces acting on the joint and protects internal structures.
Head of the humerus
The head of the humerus is the upper and rounded part of the arm bone, which articulates with the scapula at the shoulder joint. This spherical shape allows for a wide variety of arm movements in multiple directions. Thanks to its smooth surface and its fit in the glenoid cavity, it facilitates movements such as raising, rotating, and extending the arm. Additionally, it is key for shoulder stability along with muscles and ligaments.
Common fibular nerve
Sciatic nerve branch. It divides into fibular superficial and deep nerves, which innervate the leg and foot. Controls dorsiflexion of the foot (lifting the toes) and part of the sensation on the dorsum of the foot.
Pectineus
The pectineus is a short muscle located at the top of the thigh. It helps flex and abduct the hip, meaning it brings the leg closer to the body's midline.
Salivary glands
Produce saliva to initiate digestion and keep the mouth moist. They include the parotid, submandibular, and sublingual glands, and release enzymes like amylase that break down food.
Rectum
Temporarily stores stool until it is eliminated from the body through the anus.
Superior vena cava
Aorta artery
Pulmonary artery
Left atrium auricle
Heart
Right atrium auricle
Muscular organ that pumps blood throughout the body. It has four chambers: two atria and two ventricles.
Right ventricle
Left ventricle
Diaphragm
Main muscle of respiration. It contracts during inhalation and separates the thoracic cavity from the abdominal cavity.
Sacral plexus
Formed by spinal nerves L4 to S4. It innervates the pelvis, glutes, perineum, and lower limbs. The sacral plexus gives rise to the sciatic nerve, the longest and thickest nerve in the human body.
Musculocutaneous nerve
Branch of the brachial plexus. Innervates the flexor muscles of the arm (biceps, brachialis, and coracobrachialis) and the skin of the lateral forearm. Allows elbow flexion and provides tactile sensation on the outer part of the forearm
Vagina
Muscular tube that connects the uterus to the outside; allows menstruation, intercourse, and childbirth.
Nervous System
The Integrator
The nervous system links thought, sensation and movement via billions of neurons. It constantly samples internal and external environment and adjusts every other system accordingly.In physiology, signals travel clearly, attention focuses easily, and stress responses correlate with needs.
Fascinating FactEvery thought, emotion, and movement is powered by tiny electrical currents created when sodium, potassium, calcium, and chloride ions move through microscopic channels in your neurons. You literally think in electrolytes!
More detail on the nervous system
Female and male urethra
The female urethra is short and only transports urine. In men, it is longer and also expels semen. Both connect the bladder to the outside, completing the excretion process.
Male
Female
Upper jaw
The upper jaw forms the middle part of the face.Supports the upper teeth and participates in the formation of the nose and the palate.
Pharynx
Common duct to the digestive and respiratory system. It directs air from the nose or mouth to the larynx.
Endocrine System
The Timing Mechanism
Hormones secreted by glands such as the hypothalamus, pituitary, thyroid, adrenals, and gonads coordinate long-term adaptation. Through feedback loops, the endocrine system synchronises circadian rhythm, metabolism, growth, and fertility. Energy, mood, and reproduction align with the cycles of day, season, and life stage.
Your hormones are not just “chemical moods” — they’re broadcast signals of context. Every gland is asking, “What kind of world am I in, and how should this body behave?”In a moment of danger, the adrenal glands flood you with cortisol and adrenaline — gearing you for survival. In times of safety, the thyroid opens up metabolism, and sex hormones rise, inviting growth, curiosity, and connection.
More about the endocrine system
Vastus lateralis
Located on the outer part of the thigh, this muscle also belongs to the quadriceps and helps extend the knee.
Endocrine System
The Timing Mechanism
Hormones secreted by glands such as the hypothalamus, pituitary, thyroid, adrenals, and gonads coordinate long-term adaptation. Through feedback loops, the endocrine system synchronises circadian rhythm, metabolism, growth, and fertility. Energy, mood, and reproduction align with the cycles of day, season, and life stage.
Your hormones are not just “chemical moods” — they’re broadcast signals of context. Every gland is asking, “What kind of world am I in, and how should this body behave?”In a moment of danger, the adrenal glands flood you with cortisol and adrenaline — gearing you for survival. In times of safety, the thyroid opens up metabolism, and sex hormones rise, inviting growth, curiosity, and connection.
More about the endocrine system
Median nerve
Originates from the brachial plexus and passes through the carpal tunnel. Innervates muscles of the forearm and part of the hand. Allows wrist flexion and fingers, as well as the movement of the thumb. Compression causes carpal tunnel syndrome.
Axillary lymph nodes
They are located in the armpits and filter the lymph from the arm, chest, and upper abdomen. They are key in detecting infections or diseases such as breast cancer. They are usually examined in medical check-ups for their diagnostic value.
Central nervous system
The central nervous system controls vital functions and processes the body's information. It is composed of the brain and spinal cord. The brain interprets stimuli, coordinates thought, language, memory, and emotions. The spinal cord transmits signals between the brain and the rest of the body.
Myometrium
It is the muscular layer of the uterus, responsible for contractions during childbirth and menstruation.
Digital arteries
Fingers and toes itch. They originate from the palmar or dorsal arteries.
Head of the femur
The head of the femur is the spherical part and upper of the femur, the longest bone in the body. It fits into the acetabulum of the pelvis, forming the hip joint and allowing wide and stable movements. Thanks to its rounded shape and smooth surface covered with cartilage, it facilitates smooth sliding within the joint cavity.Additionally, it is key in the transmission of body weight from the pelvis to the legs.
Trachea
Tube that connects the larynx to the bronchi. It transports air to the lungs and is reinforced by cartilaginous rings.
Digestive System
The Gateway
The digestive tract is the gateway between the world and you. It welcomes, breaks down, and transforms food into energy and information. Its walls are lined with sensors, deciding what to let in and what to keep out. When it’s in balance, you feel grounded, nourished, and stable — your body trusts the world.
Fascinating FactThe barrier between “you” and “not you” is only one epithelial cell thick—thinner than cling film—yet it handles tons of antigens daily.Tight junctions and mucus make it a living fortress.
More information on the digestive system
Endometrium
Inner layer of the uterus that thickens during the menstrual cycleand detaches if there is no fertilization.
Vena cava
The vena cava is the largest blood vessel in the body. It collects oxygen-poor blood from throughout the body and carries it to the heart. It is made up of two parts: the superior and inferior vena cava.
Aorta artery
The aorta is the main artery that exits the heart. It distributes oxygen-rich blood to all organs and tissues of the body. Its branched structure allows it to irrigate from the head to the feet.