BIOL-N - Biology BIOL-N 214 Lecture Notes - Lecture 4: Stratum Granulosum, Stratum Corneum, Stratum Spinosum
27 Apr 2016
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Chapter #5 - the integumentary system: the skin (integument) Accounts for 7% of total body weight. Subcutaneous tissue consist of areolar + adipose ct. Allows skin to glide over underlying structure easily. Shock absorber + insulator (subcutaneous fat: epidermis. Produce keratin as they are pushed toward skin surface. Keratin - fibrous protein gives protective properties to skin. Protein omprised of keratin fibers + keratohyalin (protein) Keratinocytes arise in deepest part of epidermis. (from basal layer of cells - s. basale) At skin surface, they are dead, scalelike structures. Produced by keratinocytes of the stratum spinosum + granulosum. Responsible for membrane permeability characteristics: melanocytes. Found in deepest layer of epidermis (s. basale) Have spider-shape processes which touch all of keratinocytes. Melanin is shed through processes + engulfed by keratinocytes. Melanin protects cells from destructive effects of uv radiation. Uva and uvb both contribute to cancer. Uvb is a larger contributer to cancer. Golgi apparatus of melanocytes packages melanin into melanosomes.
