KAAP220 Lecture Notes - Lecture 12: Dense Irregular Connective Tissue, Stratified Squamous Epithelium, Stratum Corneum
23 Oct 2018
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Document Summary
Can be referred to as skin or integument. Body"s first line of defense against environment. Epidermis is composed of strata that have various functions. Primary cell type in epidermis is keratinocyte. Deeper layers of epidermis from epidermal ridges. Adjacent to dermal papillae (nipple shaped mound) Found on palms of hands and soles of feet. Cells get oxygen and nutrients from capillaries in the dermis. Cells with highest metabolic demand are closest to the dermis. Takes about 7-10 days for cells to move from the deepest stratum to the most superficial layer. Cells in surface layer (stratum corneum) remain about 2 weeks before being shed or washed away. Most cells here are basal cells, stem cells that divide to replace more superficial keratinocytes. Merkel cells that respond to touch are also found here. Composed of 8-10 layers of keratinocytes bound together by desmosomes. Only looks spiny when on a prepared slide.
