BIOL-N - Biology BIOL-N 214 Lecture Notes - Lecture 1: Stratified Squamous Epithelium, Stratum Spinosum, Stratum Granulosum
29 Mar 2016
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Integument = skin largest organ (7% to 8% of body weight) two layers epidermis: supericial layer of straiied squamous epithelium dermis: deeper layer of areolar and dense irregular connecive issues hypodermis (not part of the skin) lies under dermis. Kerainized straiied squamous epithelium kerain is a water-insoluble protein. 4 to 5 layers (strata) of disinct cell types. From deep to supericial (as they grow): stratum basale stratum spinosum stratum granulosum stratum lucidum (found only in thick skin) stratum corneum. Stratum basale: only layer that undergoes mitosis, one layer of cells adjacent to the dermis kerainocytes: most abundant; produce kerain to waterproof the skin. Melanocytes: cells with long, branched cytoplasmic processes; produce a pigment (black, brown, or yellow) that absorbs uv light to prevent dna damage, reducing some forms of skin cancer tacile cells: sense touch. Daughter cells from the stratum basale difereniate into nondividing (may see a rare mitoic cell), highly specialized kerainocyte.
