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functions of skin
| Question | Answer |
|---|---|
| What are the functions of the skin? | chemical barriers, physical or mechanical barriers, biological barrries, heat regulation |
| What is thermoregulation? | thermoreceptors vasoconstriction/vasodilation |
| what is transdermal absorption? | administration of certain drugs steadily through the skin via adhesive patches |
| epidermis | keratinized stratified squamous epithelium |
| dermis | connective layer tissue |
| define hypodermis | another connective tissue layer below the dermis |
| define thick skin | on palms and sole, and corresponding surfaces on fingers and toes has sweat glands, no hair follicules or sebaceous oil epidermis 0.5 mm thick |
| define thin skin | covers the rest of the body epidermis about .1mm thick posses hair follicles, sebaceous glands, and sweat glands |
| epidermis characteristics | lacks blood vessels, sparse nerve endings for touch and pain |
| keratin | tough protein in dead cells at surface |
| five types of cells in the epidermis | stem cells keratinocytes melanocytes tactile dendritic |
| stem cells | give rise to keratinoctues, in deepest layer of epidermis |
| deepest layer of the epidermis | stratum basale |
| define keratinocytes keratinocytes | great majority of epidermal cells synthesize keratin |
| define melanocytes | occur only in stratum basale synthesize pigment melanin branches processes that spread amoung keratnocytes |
| melanin | sheilds DNA from uv radiation |
| tactile layers | in basal layer of epidermis touch receptor cells associated with dermal nerve fibers |
| dendritic cells | macrophages in bone marrow guard against pathogens cause phagocytosis of toxins, and other pathogens that penetrate skin |
| Layers of epidermis deepest to superficial | stratum basale |
| stratum basale | single layer of stem cells and keratinocytes resting on basement membrane melanocytes and tactile cells are in the stem cells and keratinocytes stem cells divide keratinocytes migrate toward skin replace lost epidermal cells |
| stratum spinosum | produce keratin filament attach to desmosomes dendritic cells found through out this stratum |
| thickest layer of the epidermis | several layers of the keratinocytes |
| stratum granulosum | consist of three to five layers of flat keratinocytes contains granules- corase dark staining |
| stratum lucidum | seen only in thick skin thin translucent zone no nuclueus or other organnelles |
| stratum corneum | up to 30 layers of dead, scaly, keratinized cells form durable surface layer calluses or corns resistant to abrasion, penetration and water loss |
| what is calluses or corns | thick accumulations of dead keratinocytes on the hands or feet |
| dermis | connective tissue layer beneate epidermis |
| dermis composed of | collagen with elastic fibers blood vessels, sweat glands, sebaceous glands, and nerve endings |
| 2 layers of the dermis | paplilary layer recticular |
| papillary layer | superficial thin zone of areolar ct composed of dermal papillae, epidermal ridges and meissner corpuscles |
| dermal papillae | upward fingerlike extensions of the dermis |
| epidermal ridges | on fingertips that leave fingerprints |
| meissner corpuscles | rich in small blood vessels, free nerve endings |
| reticular layer | deeper and much thicker layer of dermis consist of dense irregular and connective tissue strech marks |
| strech marks | tears in the collagen fibers cause by the streching of the skin due to preggo or obesity |
| hypodermis | subcutaneous tissue most areolar and adipose than dermis binds skin to underlying tissue |
| subcuteanous fat in the epiderma | energy thermal insulation 8% thicker in women |
| melanin | most significant factor in skin color produced by melanocytes |
| dark skin people | produce greater qualities of melanin, breaks down more slowly |
| light skin people | produce less melanin, breaks down rapidly |
| amount of melanin varies with exposure to | UV rays of sunlight |
| hemoglobin | red pigment of red blood cells |
| define carotene | yellow pigment acquired from egg yolks and yellow/orange vegetables |
| cyanosis | blueness of the skin from deficiency of oxygen in cirulation blood |
| erythema | abnormal redness of the skin due to dilated cutaneous vessels |
| pallor | pale of ashen color, decreased blood flow to skin |
| hair | pulus. pili for plural version slender filament of keratinized cells that grows from a tube called hair follicle |
| hair is found almost everywhere on the body except | plams and soles, ventral, lateral, and distal surfaces of fingers and toes lips, nipples |
| hair is divided into three zones | bulb- swelling at the base where it originated in dermis (only living cells) root- remainder of the hair in follicle shaft- portion above skin surface |
| hair papulla | vascular connective tissue that provides the hair with its sole sourse of nuutrition |
| hair matrix | mitotically active cells above papilla |
| three layers of hair root from in to out | medulla, cortex, cuticle |
| hair receptors | nerve fibers that entwine each follicle respond to hair movement |
| piloerector muscle | bundles of smooth muscle cells goose bumps |
| fingernails and toenails | fingernails and toenails derivatives of stratum coreneum, packed with hard keratin |
| nail plate | hard part of nail that includes free edge- overhangs finertip nail body- visible attached part of nail nail root- extends proximally under overlying skin |
| eponychium | cuticle narrow zone of the dead skin that overhands this end of the nail |
| normal sweat ph range | 99% water. ph range 4 to 6 |
| acid mantle | inhibits bacterial growth |
| insensible perspiration | 500 mL/day, does not produce visible wetness of skin |
| diaphoresis | sweating with wetness of skin |
| sebacous glands | flask shaped glands with short fucts oepning into hair follicle contrains sebum infection causes acne |
| sebum | oily secreation produced by seaceous glands, keeps skin and hair from becmoming dry |
| sudoriferous glands | sweat glands |
| merocrine glands | sweat glands that function in evaporative cooling |
| apocrine glands | sweat glands that function as scent glands |
| ceruminous glands | glands of the ear canal that contribute to the cerumen |
| mammary glands | milk producing glands located in the brests |
| skin cancer | induced by uv rays of sun most often on head and neck fair skin people |
| basal cell carcinoma | most common type least dangerous b/c of selom metastasizes forms from cells in stratum basale lesion is small |
| squamous cell carcinoma | arise from keratinocutes from stratum spinosum usually on scalp, ears, lower lip have raised, reddened, scaly |
| malignant melanoma | skin cancer that arises from melanocytes often in a preexisting mole most deadly form metssizes rapidly high in men, redheads, sunburns in childhood |
| tissues repair in two ways | regeneration and fibrosis |
| regeneration | replacement of dead or damaged cells by the same type of cell as before |
| fibrosis | replacement of damaged cell with scar tissue |
| healing of a cut in the skin | mast cells and damaged cells release distamine which dilate blood vessels makes capillaries more permeable |
| blood plasma seeps into wound carrying | antibodies, clotting proteins, and blood cells |
| deep tissue repair | blood clot forms in the tissue forms scab macropahges phagocytize and digest tissue debris |
Created by:
lanahargrove