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Ariel Lopez, period 1, Integumentary System - Coggle Diagram
Ariel Lopez, period 1, Integumentary System
Major functions of Skin
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- Protection - made of 3 layers : chemical barrier, Physical barrier and biological barrier. Chemical = sweat, sebum and defensive,
- Body Temperature Regulation -
Temp increases : sweat glands produce 12 L ( 3 gallons ) to cool down the body.
Cold ENV : Dermal blood vessels constrict & skin temp lowers to slow heat loss.
- Cutaneous sensations - cutaneous sensory receptors are a part of the nervous system ; Exteroreceptors respond to stimuli outside body ; Free nerve endings sense painful stimuli.
- Metabolic Functions - Skin synthesizes Vitamin D for calcium absorption in the intestine ; Keratinocytes disarm carcinogens & activate hormones ; skin makes collagenase, aids turnover of collegan = prevents wrinkles.
- Blood Reservoir - Skin holds 5% of the body's total blood ; skin vessels constrict to shunt blood to other organs, exercising muscles.
- Excretion of Wastes - Skin secretes limited amount of nitrogenous wastes ; sweating results in water and salt loss.
Chemical = sweat ; sebum & defensive, kill bacteria ; cells secrete antimicrobial desensive ; Acid mantle, low pH retards bacterial multiplication ; Melanin is barrier against UV.
Physical = flat and dead Keratinized cells of stratum corneum, surrounded by glycolipids = block water & water-soluble subs ; chemicals = limit penetration of skin.
Biological - Epidermis contains phagocytic cells ; Dentritic cells engulf invaders & present white blood cells = activated immune response ; Dermis contains macrophages ; DNA absorbs UV radiation.
Layers of skin
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Dermis ~ strong connective tissue, made of two layers
Hypodermis ( superficial fascia ) ~ subcutaneous layer deep to skin, not apart of skin, contains Adipose tissue to absorb shock and anchors skin to underlying structure.
- Stratum corneum ( most superficial ) : Horny, 20-30 rows, flat keratinized dead cells , accounts for epidermis thickness, Protects from ENV ( water loss, abrasion / penetration , barrier )
- stratum lucidum ( thick skin only ) : Thin, translucent band ; 2-3 rows ; flat dead keratinocytes
- stratum granulosum ( granular ) : 4-6 cells , flattened & keratinized , slows water loss = cells above die
- stratum spinosum : prickly layer, 7 cell layers
- stratum basale ( Deepest ) : Attachted to dermis, rows of cells that divide ( mitotic )
Papillary - superficial layer of areolar CT ; Dermal papillae = superficial region of dermis which send finger like projections into epidermis ; thick skin lies on dermal ridges , friction ridges ( gripping, sense of touch, sweat pores = unique finger prints)
Reticular - 80% of dermal thickness, dense elastic cartilage , stretch , strength and resiliency ; Extracellular matrix contains Adipose cells.
Accessory Organs
Hair - consists of dead keratin cells ; warn of insects , guards against physical trauma & protects from heat loss, shields from heat loss.
Nails - contains hard keratin, protective cover for fingers and toes ; consists of free edge, nail plate & root.
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sebaceous Glands - widley distributed ( not palms or soles ), developed hair follicles & secreted into them, secretes sebum : oily holocrine secretion , Bactericidal ( bacteria killing ) properties & softens the skin and hair.
Structure - Hairs ( pili ) : flexible keratinized cells, produces hair follicles & contains hard keratin.
Regions : shaft - extends above shaft, Root - within scalp
Parts of Hair shaft : Medulla - central core of large cells, cortex - 7 layers of flattened cells surrounding medulla , cuticle - outer layer consisting of overlapping layers of single cells.
- Nail bed = epidermis under nail plate, Nail matrix = thick part of bed, growth ; Nail folds = skin folds overlapping boarder ; Cutice = Nail fold ; Nails pink = underlying capillaries ; Lunule = thick nail matrix
- Appocrine Sweat Gland = axillary & anogenital areas - secretes yellowish sweat and proteins ; odor & larger then eccrine.
- Eccrine ( Merocrine ) Sweat Glands = abundant on forehead, palms and soles ; ducts connect to pores ; functions thermoregulation, regulated by symphatic nervous system , secretes sweat
- Modified Glands = Ceruminous Glands line external ear ; secretes wax & Mammary Glands secrete milk.
Skin cancer & ABCDE rule
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Basal cell carcinoma - Most common, stratum basal cells proliferate & invade the dermis and hypodermis ; surgical excession cures 99% of cases.
Squamous cellcarcinoma - 2nd most common, metastasize ; involoves keratinocytes of stratum spinosum ; scally papule on scalp, ears, lips & hands ; radiation therapy or surgically.
Melanoma - cancer of melonocytes ; most dangerous = highly metastatic & resists chemotherapy ; wide surgical excision and immunotherapy
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