An animal body is made up of thousands of cells which are the basic functional units for life. When similar cells ensemble together, to perform a specialized function, a tissue is formed. Again, several tissues functionally group together to form an organ. The study of tissue is known as histology. With recent advancements in the field of microscopy, immuno-fluorescence and use of frozen tissue sections, even the minutest details can be observed in tissues, which, in turn, has refined the otherwise examined details in health and disease and led to considerable improvement in clinical diagnosis and prognosis. There are four basic types of animal tissues, namely, epithelial, connective, muscle and nervous. Although all animals in general contain these tissue types, their manifestation varies in accordance to the organism type. This article deals with the basic animal tissue types.
Different Kinds Of Animal Tissues
The basic function of epithelial tissue is to provide protection to the body’s interior and exterior. An epithelial animal tissue is composed of closely packed cells, which form continuous sheets and serve as linings in different parts of the body. Besides lining the various organs, it also serves as a separator and helps in covering the vital body organs and keeps them intact and in right position. One of the most commonly traced epithelial tissues is the outer layer of skin. Epithelial tissue also forms the lining of the mouth, lungs and stomach. The epithelial animal tissue forms the endocrine system, whose primary function is to produce hormones as well the exocrine system which is responsible for release of substances such a sweat.
The primary function of connective tissue is to structure and support the animal body. Besides containing cells, this tissue is also made up of non-living elements known as extra cellular matrix, such as salts and gases. This tissue group is known for its fibrous character. Collagen, the most common protein fiber it is made up of, adds tensile strength to the connective tissues. Not only do connective tissues provide strength, they also provide protection by filling up the void between several organs and tissues. Few examples of connective tissue include tendons, ligaments, cartilage, bone and fat tissue. Even blood is considered to be a form of connective tissue.
Muscle tissues are a form of specialized tissue, characterized by their ability to contract. Aiding in movement, the function of muscle tissues is not limited to limbs and joints. They also help in the transport of food and blood throughout the body. The movement in muscle tissue is due to the presence of specialized proteins called actin and myosin, which slide past each other and allow movement. The three subcategories of muscle tissue are smooth muscle, cardiac muscle and skeletal muscle. Whereas smooth muscles are found in the inner linings of organs, skeletal muscles are found attached to bones involved in gross movement. Cardiac muscle, on the other hand, is present in the heart, which allows it to contract and pump blood throughout the body.
The nervous tissue controls the entire animal body as a whole. The central as well as the peripheral nervous system comprises of nerve tissues. The two types of cells that make up this tissue are neurons and glial cells. The nerve tissue in the brain generates and conducts electrical signals in the brain and transmits it to the spinal cord. In the central nervous system, the nerve tissue forms the brain and spinal cord, while in the peripheral nervous system, the cranial and spinal nerves comprise of it.