The body consists of different types of tissue act different specialized function. The body consists of four main types of tissues named as connective tissue, epithelia, nerve and muscle tissue.

Cells that lie on the outside surface or gastrointestinal tract (epithelium) and internal cavities (endothelium) come in numerous shapes and forms, like cells with small beating hair as cilia in the lungs, to column-like cells that formed the stomach.

Endothelial Cells

Endothelial cells that formed internal cavities including blood vessels and glands. Lining cells regulate functions, that what can and what cannot pass through them, protect internal structures, and function as sensory surfaces.

Epithelial Tissues

The epithelial tissues, formed by cells that cover the organ surfaces, like skin, the reproductive tract, surfaces of other soft organs, and the inner lining of the digestive tract etc.

These cells also formed tight junctions, and make a blockade between the external environment to provide protective function, and helps to protect organs from microorganisms, injury, and fluid loss. Another function of these tissues is secretion, excretion and absorption.

Connective tissue

Connective tissues are those fibrous tissues called an extracellular matrix, made up of cells separated by non-living material, this matrix can be liquid or rigid. For instance, blood contains matrix as plasma while the bone's matrix is rigid.

Connective tissue gives shape to organs, blood, bone, ligament, adipose, tendon and areolar tissues are examples of connective tissues. There are three types of connective tissues, fibrous connective tissue, skeletal connective tissue, and fluid connective tissue.

Muscular tissue

Muscle tissue or muscular tissue form the active contractile tissue of the body. Functions of these tissues are to produce force and cause motion, or movement within internal organs.

There are three types of Muscular tissues: visceral or smooth muscle, found in the inner linings of organs, skeletal muscle attached to bones, which helps in body movement, and cardiac muscle found in the heart where it contracts to pump blood throughout the body.

Nervous tissue

Cells found in the central nervous system and the peripheral nervous system called nervous (or neural) tissue. In the central nervous system, neural tissues form the brain and spinal cord while In the peripheral nervous system, these tissues form the cranial nerves and spinal nerves, inclusive of the motor neurons.