BG1518_Review Skeleton, Muscles, Endocrine

Overview

In this week's lessons, we will explore the relationships between the musculoskeletal and endocrine system. Then, we will examine and discuss the latest research findings that show that skeletal muscles are glands under certain conditions.

THE SKELETAL SYSTEM

The skeletal system provides structure and support for the body. It is made up of bones, ligaments, tendons, and cartilage. The skeletal system's primary functions are to:

1. support body weight
2. enable movement
3. protect internal organs
4. produce red and white blood cells
5. store vitamin D and minerals, such as calcium and phosphorus

axial skeleton (blue)

The skeleton is grouped in two divisions: the axial (ak-see-ul) skeleton and the appendicular (a-puhn-di-cue-lar) skeleton.

appendicula skeleton (pink)

AXIAL OR APPENDICULAR

CLICK HERE TO DECIDE

The axial skeleton is made up of the bones in the head, neck, back, and chest.

The skull is formed by two groups of bones: cranial bones and facial bones. What organ is protected by the cranial bones?

The facial Skull

Nasal bones form the nose.

NASAL

The zygomatic (zye-goh-ma-tik) bones form the cheekbones.

The maxillary (max-eh-leh-ree) bones are the bones of the upper jaw.

ZYGOMATIC

MAXILLARY

TEETH

MANDIBLE

The mandible bones form the lower jawline.

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BONES IN THE EAR

The smallest bones of the skeleton are in the ear. They are called ossicles. The bones of the ear are the malleus, incus, and stapes. The common name of the malleus is the hammer, incus is the anvil, and stapes is the stirrup.

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There are 33 vertebrae in the spinal column.

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back view

front view

The thoracic (thaw-ra-sik) cage is formed by the 12 pairs of ribs and the sternum (breastbone). The thoracic cage protects the heart and lungs.

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Your appendicular skeleton is made up of the bones that are attached to your axial skeleton. The bones of your shoulders, pelvis, arms, hands, legs, and feet are all part of your appendicular skeleton.

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CAN YOU HIT THE BULLSEYE? GIVE IT A TRY!

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UPPER APPENDICULAR SKELETON

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LOWER APPENDICULAR SKELETON

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CAN YOU IDENTIFY THE BONES OF THE SKELETON?

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THE MUSCULAR SYSTEM

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Cardiac muscle is found only in the heart. This type of muscle is involuntary, which means it functions automatically.

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Smooth muscle is involuntary. This type of muscle lines the walls of blood vessels and the organs in the respiratory, digestive, urinary, and reproductive systems.

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Skeletal muscles connect to the bones of your skeleton from head to toe. They allow you to perform a wide range of voluntary movements.

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Muscles can only pull; they cannot push. Thus, muscles are grouped in pairs: a muscle pulls in one direction, and another muscle pulls in the opposite direction.

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Trapezius: (traps) truh-pee-zee-us

The trapezius muscles are a pair of large triangular muscles extending over the back of the neck and shoulders. They move the head and shoulder blade.

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Deltoids (aka delts) del-toyds

The deltoids are the triangular muscles of the shoulder. They twist the arms and raise them sideways.

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Latissimus dorsi (lats) luh-ti-suh-mus / dor-see

The latissimus dorsi muscles are the largest muscles in the back. They help you inhale when you breathe and do things like pull-ups and swimming.

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Pectorals (pecs) pek-tuh-rals

The pectoral muscles are your chest muscles. They help you bring your arms close together to the center of your body, like when you clap your hands. They also push your arms out in front of you with a chest press. Your pecs also help you inhale when you breathe.

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The biceps are large, thick muscles on the front of your upper arms. They pull your arms towards your face.

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The triceps are large, thick muscles on the back of your upper arms. They pull your arms towards your feet.

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The Abdominals (abs)

Your abdominal muscles are the central stomach muscles, often referred to as the six-pack. (Everyone has a six-pack, but it is less visible in some people than others.) The abs protect the internal organs and assist in breathing. They also enable you to bend, twist, and maintain good posture.

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Obliques oh-bleeks

The obliques are your waist muscles. You use them when you bend forward or backward or side to side or twist the trunk of your body. The obliques assist in breathing and support the spine, helping you to maintain good posture.

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Gluteus maximus (gluts) gloo-tee us / max-uh-mus

The gluteus maximus muscles are the largest ones in the body. They are some of your strongest muscles, too. They move your thighs backward and away from your hips and help you to stand up from a seated position.

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Quadriceps (quads) kwa-druh-seps

The quadricep muscles are located at the front of the thighs. They perform the opposite action of the gluteus maximus muscles. The quadriceps flex your thighs – move them forward – and straighten your knees.

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Hamstrings

The hamstrings run down the backs of your thighs. They move the thighs backwards and bend the knees. These muscles are used for such activities as standing, walking, running, and jumping.

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Gastrocnemius (ga-strok-nee-mee-us)

The gastrocnemius muscles are your calf muscles. These muscles flex your leg at the knee joint and your foot at the ankle joint. (You flex your foot when you point your toes upward – toward your knee.)

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Review the major muscles of the body.

Click on Muscle Man to take a short quiz.

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THE ENDOCRINE SYSTEM

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The endocrine system is a network of glands scattered throughout your body. Glands are organs that make hormones and send them directly into your bloodstream to do specific jobs in your body.

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Hormones are chemicals that coordinate different processes in your body by traveling through your bloodstream to your organs, skin, muscles, and other tissues. Hormones help the body to maintain homeostasis -- a state of balance among all the body systems, enabling the body to survive and function correctly.

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Environmental conditions and personal responses to stimulation trigger the release of different hormones that influence feelings and behavior in different people.

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Hover over an image to learn about the featured endocrine glands.

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The parathyroid gland is a set of four small glands located behind the thyroid gland in your neck. This gland plays a role in bone health by managing calcium and phosphorus levels.

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Click on the image for "ANOTHER" quiz

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Skeletal Muscles as Endocrine Glands

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Skeletal muscles are organs attached to the bones of the skeleton. Many skeletal muscles are small, like those in the face, hands, and feet, and enable fine motor movement. However, most skeletal muscles are large, like those in the arms, legs, and trunk (chest, abdomen, pelvis, back, shoulders, buttocks).

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Skeletal muscles account for about 40% of body weight and require the highest percentage of energy resources to fuel the body compared to other organ systems.

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Fifty percent of the estimated 86 billion neurons in the brain are in the cerebellum, which is the part of the brain responsible for controlling balance, posture, and coordination. Thus, powering the body consumes a large amount of neural resources.

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In recent years, scientists have discovered skeletal muscles do more than enable movement. Research shows that skeletal muscles are endocrine glands that release hormones called myokines (my-oh-kines).

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Skeletal muscles produce myokines during physical activity. The greater the physical exertion, the more myokines muscles produce. Therefore, exercises like walking, running, and weightlifting stimulate myokine production.

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Myokines have many positive effects on bodily functions, such as:

• Metabolism: Myokines stimulate the pancreas to produce insulin, which rids the body of excess sugar and burns fat cells.
• Immunity: Myokines regulate the immune system by binding to white blood cells, triggering an immune response that strengthens the body's defenses.
• Cognitive function: Myokines affect mood, learning, and brain plasticity – the brain's ability to change its structure, functions, or connections in response to stimuli. Brain plasticity is especially beneficial when one experiences diseases or injuries that affect neural pathways.

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Research into myokine hormones is ongoing. Scientists are discovering that myokines can destroy cancer tumors, improve the microbiome (the community of bacteria, fungi, and viruses native to each individual) in the digestive system, reverse diabetes, and accomplish many other tasks that improve health and prolong life.

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JOIN A GAME

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JOIN A GAME

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