BIO210Y5 Lecture Notes - Lecture 2: Extracellular Fluid, Melanocyte, Basal-Cell Carcinoma
Document Summary
Epithelial tissue: - includes the surface of your skin. Cellular layers of different types that cover exposed surfaces and line internal cavities. Organized groups of cells that contain epithelial- derived cells that synthesize substances for secretion. Secretes onto external surfaces or internal passageways that connect to the exterior. Secrete hormones into the interstitial fluid that then enters the bloodstream. Functions of epithelial tissue: provide physical protection, control permeability regulation of any substance that enters or leaves the skin. Module 4. 4: epithelia lack blood vessels, and for this reason, they are said to be avascular. Epithelial cells must obtain nutrients by diffusion or absorption across either the exposed or the attached epithelial surface. Cells forming the deepest layer of an epithelium must remain firmly attached to underlying connective tissue because that"s how it is nourished. Dermis: consists of a papillary layer of areolar tissue and a reticular layer of dense irregular connective tissue.
