BIOL 030 Lecture Notes - Lecture 9: Stratum Corneum, Stratum Lucidum, Stratum Basale
16 Sep 2020
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Document Summary
Thick (glabrous) skin lacks hair and sebaceous glands. Refers to thickness of epidermis only, not thickness of entire skin with dermis. Thin (hairy/non-glabrous) skin characterized by presence of hair & sebaceous glands. Another diagnostic characteristic reduced thickness of stratum corneum, granulosum & spinosum (basically the three outermost) Keratinocyte produces keratin, main cell of epidermis. Langerhans cell mobile immune system cells scattered in stratum spinosum. Appearance - stellate shape with many branches, clear cytoplasm. Merkel cell cutaneous mechanoreceptors responsible for light touch. Cytomorphosis differentiation and maturation (takes 26-30 days) Keratinocytes do this, they start in the stratum basale and move to stratum corneum. As keratin builds up the cells start to die, this is the degeneration phase. Keratin fibrous proteins that make up intermediate filaments. Amount of keratin in the cell increases as it migrates toward surface. Fibronectin in basement layer regulates rate of keratinization. Epidermal growth factor stimulates proliferation of keratinocytes.
