BIOL302 Lecture Notes - Paracrine Signalling, Cell Membrane, Cytoskeleton
19 Sep 2013
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Definition: membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs. Epithelia are sheets of cells that are linked tightly together by intercellular junctions. The major function of epithelia is to form barriers between two compartments. Cells readily divide to make more cells; helps for recovery after an abrasion. No blood vessels; epithelial is often damaged when things move against it, it would not make sense for blood vessels to be present since you would bleed every time you scraped your skin or swallowed something rough. Tight junctions are present; to act as a barrier so fluids don"t leak in or out. Protection: abrasion resistance through dead epithelial cells at surface that can be sloughed off (external) and mucous secreting cells (internal).
