BIOL 222 Lecture Notes - Lecture 5: Dihydrotestosterone, Subcutaneous Tissue, Stratum Basale
Document Summary
Skin (largest organ: 2 distinct regions, epidermis- superficial region, keratinized stratified squamous epithelium & avascular. 4 cell types: keratinocytes (protein called: keratin, melanocytes (pigment: melanin, melanosomes, dendritic cells (langerhans, macrophages that activates immune system, tactile cells (light touch & pressure: merkel, sensory receptors. Functions of skin: 1st & foremost a barrier, main functions: protections, body temp. regulation, cutaneous sensations, metabolic functions, blood reservoir, excretion of wastes, protection: Skin is exposed to microorganisms, abrasions, temp, & harmful chemicals. 3 barriers: chemical- sweat, sebum defensing, melanin, acid mantle, physical- stratum corneum, biological-phagocytic cells (dendritic cell, macrophage) Hair: slender filament of dead, keratinized cells that grows from hair follicles, found everywhere on body expect: sides of soles. & feet, lips, external genitalia, hands & palmar surface of fingers. Responsible for goosebumps: hair papilla dermal tissue containing a knot of capillaries that supplies nutrients to growing hair. Homeostatic imbalance for hair: hirsutism- excessive hairiness due to tumor in the ovary & adrenal gland.
