Animals: vital functions

Vital functions

Intro

Animal classification

Nutrition: obtaining nutrients

Nutrition: respiration

Nutrition: circulation & excretion

Interaction: sense organs

Interaction: coordination & effectors

Reproduction: asexual & sexual

Reproduction: fertilization and embryonic development

Animal kingdom

• Multicellular: with eukaryotic animal-type cells that form tissues. They can form organs and systems.
• Normally symmetrical body:
• Radial symmetry: several planes (starfish)
• Bilateral symmetry: one plane, two halves (humans)
• Asymmetrical: without symmetry.
• Nutrition:
• Heterotrophic
• Herbivores

• Carnivores
• Omnivores
• Interaction:
• The most complex ones have nervous system and sense organs.
• The majority move because they have locomotion organs and have developed a muscular system.
• Reproduction:
• Sexual
• Asexual
• Embryonic development:
• Oviparous: development inside an egg (birds)
• Viviparous: development inside the body of the female (mammals)
• Ovoviviparous: development inside an egg inside the female's body (vipers)

Animal classification

Invertebrates:

• They do not have an internal skeleton with a spinal column. They may have a rigid protective cover (shell, carapace, exoskeleton)
• Symmetry: radial, bilateral or asymmetrical.
• Oviparous: when they are born they can be very different from adults. In that case they undergo a process of change called metamorphosis.

Vertebrates:

• Internal skeleton with a spinal column
• Body divided into three parts:
• Head: brain and skull
• Trunk: spinal column. It can be extended as a tail.
• Extremities: they are adapted to the locomotion system (legs, wings...).
• Bilateral symmetry

Nutrition: obtaining nutrients

Food:

• Heterotrophs. Nutrients come from another living being.
• Types:
• By direct absorption from the environment (tapeworm)
• By filtering food present in the water (sponge)
• By ingestion through the mouth (mammals)
• There are specific structures: claws, tentacles, teeth, etc., to facilitate the intake of food

Digestion:

• Transformation of food into nutrients (simpler molecules capable of being incorporated into cells).
• Animals without a digestive system:
• Sponges (poriferans)
• Animals with a digestive system:
• The digestive process has several stages
• Types of digestive systems

Nutrition: respiration

Allows animals to take in oxygen, which is necessary to obtain energy through cellular respiration, and expel carbon dioxide, a waste product generated during cellular respiration.Types:

• Diffusion

• Tracheae

• Cutaneous Respiration

• Gills

• Lungs

Nutrition: circulation & excretion

• Simpler Animals (poriferans and cnidarians): direct exchange of substances with the external environment.
• More Complex Animals: exchange of substances through an internal fluid.

Circulatory System

• Types of Circulation:
• Open Circulation

• Closed Circulation

Excretion

• Cellular activity produces waste.
• Simpler Animals

• More Complex Animals

Interaction: sense organs

Formed by receptors and a nervous connection that sends information from the environment sensed by the receptor to the coordination system.PhotoreceptorsMechanoreceptorsChemoreceptorsThermoreceptors

Interaction: coordination & effectors

Nervous System

1. Receives signals from sensory organs.
2. Interprets those signals and generates responses.
3. Transmits those responses to effector organs.

NeuronsEndocrine System

• Coordinates stimuli from inside the organism.
• Composed of a group of glands.
• Glands produce hormones.
• Hormones act on specific cells, triggering slow but long-lasting responses.

Effectors

• Glands
• Locomotor system

Reproduction: asexual & sexual

Asexual Reproduction

• Occurs in some invertebrates.
• Can be alternated with sexual reproduction.
• Different types

Sexual reproduction

• Occurs in most animals.
• Requires a male, a female, and gametes.
• Gametes are the sex cells
• Sex

Reproduction: fertilization and embryonic development

Fertilization

• The union of gametes.
• Results in the formation of a zygote.
• Two different types: external & internal.

Embryonic development

• From the formation of the zygote to the development of the embryo and the birth of a new individual
• Different types: oviparous, viviparous & ovoviviparous.

Photoreceptors

• Simple eyes
• They only detect light intensity.
• Vision is not clear.
• Most invertebrates
• Compound eyes
• Formed by units called ommatidia.
• The union of all the images generates a mosaic view.
• Crustaceans and insects
• Camera eyes
• Formed by:
• Protective transparent layer.
• Lens that focuses light. Layer of photoreceptor cells.
• Clear vision.
• Cephalopods and vertebrates.

Glands:

• Release substances (hormones, enzymes, etc.) that perform very specific functions.
• Examples: adrenaline, venom, milk…

Locomotor system:

• Invertebrates:
• Exoskeleton:
• Muscles and articulated appendages (wings, legs) are attached to it.
• Found in arthropods and other invertebrates.
• Vertebrates:
• Endoskeleton:
• Composed of bones or cartilage.
• Muscles are attached to the skeleton, enabling movement.
• Found in mammals, birds, reptiles, amphibians, and fish.

Oviparous animals:

• Embryo:
• Develops inside an egg.
• Feeds on the yolk (nutritive substances stored in the egg).
• Eggs:
• Without a waterproof shell: need to be laid in aquatic environments (e.g., fish and amphibians).
• With a waterproof shell: can be laid in terrestrial environments (e.g., invertebrates, birds, and reptiles).

Viviparous animals:

• Embryo:
• Develops inside the mother’s uterus.
• Feeds through the placenta.
• Birth: the new individual is expelled from the mother’s body.
• All mammals are viviparous (except monotremes).

Ovoviviparous animals:

• Embryo:
• Develops inside an egg that remains within the female’s body.
• Feeds on the yolk inside the egg.
• Examples: sharks and vipers.

Wastes are eliminated directly by the cells in contact with the external environment

• The fluid (blood) always circulates within the vessels.
• Found in vertebrates and some invertebrates, like annelids.

• Found in simple animals like poriferans and cnidarians.
• Substances pass directly through the cell membrane.
• Cells are in direct contact with the external environment.

• Transports nutrients to all the cells of the body.
• Collects waste substances expelled by cells.
• Substances circulate through ducts or vessels in an internal fluid propelled by the heart.

• Internal fluids collect waste products.
• Excretory Organs: filter the fluid, and wastes are expelled to the outside. Examples include kidneys in vertebrates and nephridia in annelids.
• Other Organs: besides their primary function, they also eliminate wastes. For instance: the respiratory system eliminates CO₂ in many animals.

• Fluid (hemolymph) exits the vessels and bathes the tissues of the animal.
• Found in many invertebrates, such as arthropods and mollusks.

• Consist of tubes and cavities through which air circulates.
• Surrounded by blood vessels, allowing blood to transport gases throughout the organism.
• Found in amphibians, reptiles, birds, and mammals.

• Tubes that connect to the external environment.
• Branch extensively inside the animal.
• Found in some arachnids and insects

• Composed of layers where oxygen-rich water circulates.
• In contact with blood vessels, allowing oxygen to pass into the bloodstream.
• Found in amphibian larvae, some worms, mollusks, crustaceans, echinoderms, and fish.

1. Mechanical breakdown of food: reducing it to small fragments.
2. Chemical digestion: separating nutrients from ingested food.
3. Nutrient absorption: through the digestive system walls into the bloodstream.
4. Expulsion of digested waste to the outside.

1. They filter food particles present in water that enter through their pores.
2. They have specialized cells that capture and digest them.
3. Nutrients then diffuse to the rest of the organism's cells.

• Occurs through the surface of the body.
• Common in animals with very thin and always moist skin.
• Found in many worms and amphibians.

• Gastrovascular cavities: sac-like structures with a single opening functioning as both mouth and anus.
• Digestive tubes: tubes with an entrance (mouth) and an exit (anus). Specialized segments handle different digestive processes (digestion, absorption, etc.).
• Digestive glands: present in complex animals. They produce substances (enzymes) that assist in chemical digestion.

• They detect:
• Vibration
• Movement
• Gravity
• Pressure
• Examples:
• Sound receptors: in the ear.
• Touch receptors: throughout the body.
• Vibration or movement receptors: the lateral line of fish.

• Smell organs:
• Detect substances in the air.
• Examples: antennae and nostrils.
• Taste organs:
• Detect chemical substances dissolved in a liquid medium.
• Examples: taste buds.

• They detect temperature changes.
• In most vertebrates, they are located in the skin.
• Pit organ: in snakes. It detects the body heat of prey.

• Cells of the nervous system.
• They form a network throughout the organism.
• They transmit information in the form of nerve impulses: very fast but short-lived responses.
• In complex animals, neurons group together to form:
• Ganglia
• Brain
• Spinal cord
• Nerves

• They are produced in the gonads.
• Male gonads or testicles produce sperm.
• Female gonads or ovaries produce eggs.

Budding:

• The organism reproduces from a bud that grows on the surface of the parent.
• Typical in sponges and cnidarians.
• Offspring can remain attached or separate from the parent.

Fragmentation:

• The parent's body divides into fragments.
• Each fragment develops into a new individual.
• Regenerating a part of the body (like lizards or starfish do) is not reproduction.

Unisexual animals:

• Have only one type of gonad.
• Sexual dimorphism may occur (males and females look different, as in many bird species).

Hermaphroditic animals:

• Have both types of gonads.
• It is rare for them to self-fertilize

External fertilization:

• Occurs outside the female’s body.
• Coupling may occur: the male embraces the female to release gametes simultaneously.
• Typical in aquatic animals.

Internal fertilization:

• Occurs inside the female reproductive system.
• Copulation is the union of the reproductive organs of the parents.
• Courtship is the pre-mating behavior in some animals, such as singing, dancing, or displays of strength.