01:377:213 Lecture Notes - Lecture 18: Stratum Granulosum, Stratum Spinosum, Stratum Corneum
20 Dec 2019
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Document Summary
Stratum basale (deepest) - contains epidermal basal (stem) cells. Stratum spinosum - langerhans cells and melanocytes are often present. Stratum granulosum - keratin fibers develop as cells become thinner and flatter; cell membranes thicken and the cells die. Stratum lucidum - appears as a glassy layer in thick skin only. Stratum corneum (most superficial layer) - permits slow water loss by insensible perspiration. Thick skin - found on palms and soles. Thin skin - found on the rest of the body. Made of four layers of cells, because the stratum lucidum is typically absent. Dermal ridges - stratum basale forms dermal ridges. Sensitive to light contact with the skin. Monitors distortions and movements of hairs on the body surface. Free nerve endings synapse with merkel cells in the stratum basale of the epidermis. Common on eyelids, lips, fingertips, nipples, and external genitalia. Sensitive to initial contact and low-frequency vibration. Sensitive to stretching and distortion of dermis.
