Tissues are made up of cells and intercellular substance. Each fabric has a strictly defined function. The functions performed are interconnected with the structure. Therefore, the tissues are highly specific.
Tissue is a group of cells and intercellular substance that have a common origin and development, a similar structure and perform a specific function.
The following types of tissues are distinguished in the human body:
Epithelial tissue consists of tightly compressed cells (there is little intercellular substance), which perform barrier, protective and secretory functions. It forms the integument of the body, mucous membranes, glands.
Connective tissue cells are surrounded by a developed intercellular substance (in the form of fibers, bone plates, cartilage, fluid).
These structural features allow the connective tissue to perform supporting (bones, cartilage, tendons), protective (subcutaneous fat), nutritious (blood, lymph) functions.
Muscle tissues perform contraction of the heart and skeletal muscles, internal organs, and changes in the lumen of blood vessels.
Depending on the characteristics of the location and the functions performed, it happens:
- striated skeletal muscle tissue;
- striated cardiac muscle tissue;
- smooth muscle tissue of blood vessels and internal organs (stomach, bladder, etc.).
More intensive work of the heart and skeletal muscles determined the structural features of the striated tissue, in contrast to the smooth one.
Striated muscle tissue consists of developed multinucleated muscle fibers. Smooth tissue is formed by short mononuclear muscle fibers.
Nervous tissue is represented by neurons and neuroglia.
It ensures the transmission of excitation from nerve endings (receptors) to the central nervous system, and from it to the organ.
This is possible due to the special structure of neurons. A neuron has a body, a long process (axon), and short processes (dendrites).
Nerve tissue is located in the brain and spinal cord, nerve nodes, nerve fibers.