BIOL 1410 Lecture Notes - Lecture 9: Stratified Squamous Epithelium, Adipose Tissue, Melanin
15 Dec 2015
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Topic ix: integumentary system: integumentary system: overview. Consists of: skin, hair, nails, glands, sense receptors (nervous, muscles (fig 5. 1, skin-layers. 2 layers: epidermis upper layer, dermis lower layer. Below skin = hypodermis = adipose tissue. Separated into 4-5 strata (sub-layers) based on cell types: stratum basale base layer. Migrate to surface as new cells produced in basale: melanocytes (10%) Produce pigment (melanin) for uv light protection: e. g. sunburns, wrinkles (collagen damage), cancer (dna damage). Contains dark staining granules (3-5 cell layer) Flat, dead cells (too far from blood supply) (anything. Limited cell division: stratum granulosum, stratum lucidum above are dead cells) Visible only in thick skin: stratum corneum. 20 - 30 layers of flat dead cells filled with keratin (tough protein), surrounded by waterproofing glycolipid (prevents water loss) New epidermis every 2-3 weeks: dermis. Contains blood vessels, nerves, glands, hair follicles. 2 sub-layers (ct from mesoderm): papillary layer (beneath epidermis) (pilla=upward projection)
