BIO 1140 Chapter Notes - Chapter 39: Nervous Tissue, Proteoglycan, Muscle Tissue
12 Aug 2016
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39. 2(a) epithelial tissue forms protective, secretory, and absorptive. Epithelial tissue: tissue formed of sheet-like layers of cells that are usually joined tightly together, with little extracellular matrix material between them. Protect body surfaces from invasion by bacteria and viruses. Cover body surfaces and the surfaces of internal organs. Epithelium of the external surface of arthropods secretes their tough cuticle. Scales, nails, claws, hooves, horns, hair and feathers. Allow ions and small molecules to leak from the blood into surrounding tissues; allow passage of blood cells and proteins. Apical surface: the outer surface of epithelial cells. May be exposed to water, air, or fluids within the body. Covered with cilia that move eggs from the ovaries to the uterus. Basal surface: the inner surface of epithelial cells. Adhered to a layer of ecm secreted by the epithelial cells called the basal lamina: a membrane secreted at the inner surface of epithelial cells.
