what is epithelial tissue
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Answer:
Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception.
Epithelial tissues are thin tissues that cover all the exposed surfaces of the body. They form the external skin, the inner lining of the mouth, digestive tract, secretory glands, the lining of hollow parts of every organ such as the heart, lungs, eyes, ears, the urogenital tract, as well as the ventricular system of the brain and central canals of the spinal cord.
The cells making up epithelia are often closely bound to one another through specialized structures called tight junctions. They are also free from blood vessels and nerves and are supported by a connective tissue called the basement membrane. They have polarity with a distinct basal domain facing the basement membrane and the other apical surface facing the lumen of an organ or the external environment.