ANHB1101 Lecture Notes - Lecture 36: Vellus Hair, Sebaceous Gland, Apocrine
5 Sep 2018
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Skin are derived from ectoderm, dermis from mesoderm (muscle from mesoderm as well). No hair or sebaceous glands, has sweat glands. Stem cells - keratinocytes - move to surface - die off. Dendritic cells - macrophages to defend against pathogens. Blood vessels, sweat glands, sebaceous glands, nerve endings. Thin zone of areolar tissue under basement membrane near dermal papilla (covered by epidermal ridges). Respond to stress and sexual stimulation (pheromones) Resistance to trauma/infection, barrier functions (water resistant,uv radiation, harmful chemicals), vit d synthesis, sensation, thermoregulation via thermoreceptors, nonverbal communication (spacial expressions). Required for vitamin d for bone health. Causes skin cancer and breaks down folic acid. Uva and uvb initiate skin cancer (enter epidermis and dermis) Epidermal thickening - epidermal thickening by accumulation of keratinocytes. Melanin - produced by melanocytes. deposit melanin into keratinocytes. then sits above nucleus (shades it from sun). Colour fades as melanin is degraded/no longer required. Darker = eumelanin (more effective at blocking uv rays).
