BISC 101 Chapter Notes -Microorganism, Scleroprotein, Cuticle
9 Oct 2012
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Skin (cutaneous membrane) external surface of body; weighs about 7% of body weight. Epidermis superficial, thinner, epithelial tissue portion. Dermis deeper, thicker, connective tissue portion: deep in the dermis is the subcutaneous layer (aka hypodermis), but is not part of the skin. Fibers extend from the dermis and anchor the skin to the subcutaneous layer, which connects to muscles. The subcutaneous layer stores fat, large blood vessels that supply the skin, and nerve endings sensitive to pressure. Epidermis composed of keratinized stratified squamous epithelium; contains four cell types: 90% of epidermal cells and produces: keratin a tough fibrous protein that helps protect skin and underlying tissues. Produces melanin yellow-red/brown-black pigment that contributes to skin color and absorbs uv light. Helps other cells of the immune system recognize an invading microbe and destroy it. Least numerous of epidermal cells and located in the deepest layer of the epidermis.
