Anatomy and Physiology of Animals
The word “animal” is used to describe any living thing capable of moving as well as using its muscles to move about on its own. Animals are classified into three major categories according to their method of locomotion: land animals, air animals, and aquatic animals. Among all the animals, mammals, birds, and reptiles are the only ones that do not require the nervous system to function. Almost all the animals are made up of tissues and cells that are made up of protein. The word “animal” is derived from the Greek word “animus” meaning soul.
An animal’s nervous system consists of very many parts, including the brain, muscles, nerves, veins, organs, bones, skin, and exoskeletons. Each and every part of an animal have a specific job to perform, and each part is executed by the other parts. Muscles perform the function of movement, organs perform the function of digestion, nerves give messages to the brain, veins carry blood from the lungs to the other organs, and skin protects the body from injuries. The brain of an animal also contains different parts, which include the cerebrum (the inner organs of the brain), cerebellum (the part responsible for coordinating external stimuli like sight, touch, hearing, etc. ), olfactory bulb, superior cervical ganglion (the thick white area near the eyes), temporal bone, and brain stem.
Many animals possess specialized sensory organs, such as sense of smell, taste, touch, vision, and hearing. Many animals possess certain organs for reproduction, while most animals possess organs that aid in the survival of their species. All animals have the ability to sense temperature, although not all animals can sense body temperature. All animals have some sense of direction, although not all animals have the same sense of direction. All animals have sense of balance, although not all animals possess the sense of balance.
An animal’s skeleton is made up of various layers. The inner layer, the epidermis, is composed primarily of keratin; the outer layer, the dermis, is made up of connective tissue. Most animals have teeth that are made up of the enamel and bony material. The nerves and blood vessels are located in the brain and spinal cord. An animal’s digestive system consists of both a colon and a large intestine, while its respiratory system consists of the trachea, lungs, trachea linings, bronchioles, spleen, gallbladder, liver, small intestines, large intestines, lungs, and nasal cavity.
Each animal has varied characteristics due to their unique physiology and anatomy. Insects, plants, fungi, andacteria are only a few examples of multicellular organisms. Animals make up a vast majority of the Earth’s population. Bacteria, yeasts, protozoa, single-celled algae, protozoa and other microorganisms form a part of the earth’s food chain.
Every animal has a nervous system, which is present in all animals except insects. The nervous system controls the functions of all animals, including the glands, the eyes, the genital organs, the immune system, the digestion, the excretory system, the muscles, the respiratory system, the cardiovascular system, and many other activities. The brain of an animal is generally smaller than that of a human and is completely covered by the skull. Some animals (e.g., reptiles) do not possess a brain. Animals have the most vital organ systems in their body: the liver, the heart, the stomach, the kidneys, the lungs, the intestines, the blood circulatory system, the skin, the sensory organs, the nervous system and many other vital organs.