BIOL 2P93 Lecture Notes - Histology, Hair, Subcutaneous Tissue
4 Feb 2013
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Epidermal ridge: projects into dermis for epidermis-dermis attachment, prominent in thick skin. Stratum granulosum: apoptotic cells and exocytosis of lamellar bodies. Stratum spinosum: nonproliferative, desmosomes keep cells attached to each other. Stratum basale: proliferating cells, hemidesmosomes attach to dermis. Melanocytes: cells with clear cytoplasm and prominent nuclei that transfer melanin to keratinocytes. Langerhans" cell: immune protection in spinous layer. No intrinsic blood supply to epidermis; nutrients diffuse from plexus iii. Dermal papillae: projects into epidermis for epidermis-dermis attachment, prominent in thick skin. Sandwhiched by capillary plexi iii (superficially) and ii (deeply) Meissner"s corpuscle: touch receptor, found in dermal papillae, laminated appearance. Pacinian corpuscle: pressure/vibration receptor, found deeper in dermis, onion-like appearance. Pilosebaceous unit: only found on hairy skin! Hair follicle: hair bulb found in dermis or hypodermis, but cells actually derive from epidermis. Sebaceous gland: secretes sebum into hair shaft which is open to outside environment. Arrector pili: muscular contraction causes hair to stand on end.
