Summary NR 302 Exam 2 Concept Review.pdf

CH.12 Structures and functions of skin, hair, nails Skin: 3 layers 1. Epidermis (outer): thin but tough, cell are bound tightly together that form a rugged protective barrier. The inner basal layer forms new skin cells. 2. Dermis: is the inner supportive layer consisting of connective tissue, or collagen . This is tough , fibrosis area that enable skin to resist tearing. The sensory receptor, blood vessel, and lymphatics lie in the dermis. 3. Subcutaneous layer: composed of adipose tissue, which is made up of lobules of fat cells. This layer store fat for energy, provide insulation for temperature control , aid in protection by its soft cushion effect. Hair: are threads of keratin composed of 3 parts 1. Hair shaft: visible, projecting part 2. Hair root: Below the surface embedded in the follicle. 3. At the root, Hair bulb: Is expanded area where the new cell are produced in high rate. There are 2 types of hair 1. Vellus hair (fine, faint): Cover most of the body (Except the palm, soles, dorsa and distal part of the fingers, umbilicus, penis glans, inside the labia) 2. Terminal hair: The darker, thicker hair that grows on the scalp and eyebrows and after puberty, on the axillae, pubic area, the face and chest in the male. Nail: Hard plate of Keratin on the dorsal edges of the finger and toes. Nail plate is clear, white fine longitudinal ridge that become prominent in aging. Nail take their pink color is form the underlying nail bed of highly vascular epithelial cells. The lunular is white, opaque, semilunar area at the proximal end of the nail.