Chapter 6 integumentary system skin hair nails glands nerves disorders

protection – abrasion, infection, antimicrobial water barrier - cornification skin vitamin D – UV absorption senses – heat, cold, touch, texture, pressure, vibration, injury, pressure thermoregulation – skin sensors, brain responses communication - expressions

stra. corneum – dead, keratinized – protects, abrasion, water loss stra. lucidum – thick skin, eleidin, no nuclei or organelles stra. granulosum-3-5 layers, keratinocytes (keratohyalin),cyto granules stra. spinosum– thickest layer, mitotic, dendritic cells(immune), tight junction, desmosomes, dermicidin, defensins, pH stra. basale – single layer of cells on basement membrane, melanocytes, tactile, stem cells dermis – collagen, elastic, reticular, fibroblasts, BV, sweat glands, sebaceous glands, nerve endings, papillary layer at epi, epidermal ridges, reticular layer deep (dense irreg CT) hypodermis – areolar, adipose, BV, nerves

hair pilus – pili keratinized cells form a hair follicle functions protection, insulation, sex (odoriferous)

hair has three divisions bulb – contains richly vascular CT swelling the dermal papilla, surrounding it is a mitotically active area the hair matrix, all parts of a hair above this area is dead root – all of hair within skin, 5 layers shaft – hair above skin, pore about shaft

hair root is made up of medulla- loose cells, air spaces cortex- elongated cornified cells cuticle- many layers of thin overlapping cells int root sheath- epidermal tissue which surrounds the dermal papilla and contains stem cells which produce the hair cells and layers ext root sheath- dense collagenous CT dermal tissue which surrounds the int root sheath

the cycle of a hair anagen - stem cells multiply, follicle moves deeper into dermis, hair matrix producing cell types and pushes shaft and cells up, old hair pushed out, lasts 6-8 years catagen- growth stops, hair bulb keratinizes, lower follicle degenerates and hair becomes degenerating club hair, follicle begins to move up telogen- dermal papilla moves up to bulge, club hair falls out, in telogen or next anagen

glands sweat (sudoriferous) - apocrine- groin, axilla, areola, beard - exocytosis of a thick fatty secretion, pheromones, - stress & sex - merocrine(eccrine) - all over – cool body, excretion, acid mantle, constant(500 ml), diaphoresis(copious) sebaceous- sebum – holocrine onto hair follicle, old cells & fat ceruminous – external ear canal – cerumen(ear wax) – pliable ear drum, waterproof canal, antimicrobial, coats guard hairs mammary – milk producing – develop during pregnancy & lactation- modified apocrine sweat – ducts lead to nipple