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Integumentary system and skin Lecture 2

Thermoregulation, Healing and Aging. Integumentary system and skin Lecture 2. Regulation of Body Temperature. Slight shifts in temperature can disrupt metabolic rates Stable temperature is a balance between heat lost and heat produced Cellular metabolism produces heat

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Integumentary system and skin Lecture 2

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  1. Thermoregulation, Healing and Aging Integumentary system and skin Lecture 2

  2. Regulation of Body Temperature • Slight shifts in temperature can disrupt metabolic rates • Stable temperature is a balance between heat lost and heat produced • Cellular metabolism produces heat • Skeletal and cardiac muscle and liver cells are very active • Skin is key to thermoregulation

  3. Rise in Body Temperature • Nervous system signals organs to release heat • Blood is warmed and reaches the brain • Signal sent to dermal blood vessels to relax (vasodilation) • Vessels dilate • Heat from blood escapes to outside • Deeper blood vessels signaled to contract (vasoconstriction) • Blood diverted to surface • Skin reddens • Heart stimulated to beat faster and move more blood out of deeper regions

  4. Radiation- heat radiates from warmer surfaces to cooler surroundings • Conduction- heat moves from body to a cooler object in contact • Convection- heated air moves way from body and is replaced with cooler air moving toward the body (circulates) • Evaporation- sweat is released onto skin surface and evaporates, carrying heat away

  5. Drop in Body Temperature • Walls of dermal blood vessels contract (vasoconstriction) • Flow of heat-carrying blood is decreased • Reduces heat loss by radiation, conduction and convection • Sweat glands remain inactive • Muscles cells in skeletal muscles may begin to contract • Increases cellular respiration and releases heat • Rhythmic, strong contractions cause shivering

  6. Problems in Regulation • High humidity • limits or represses evaporation • Sweating is ineffective • High air temperature • Decreases heat loss by radiation • Can also cause heat gain from surroundings • Hyperthermia- body temperature exceeds 106F • Weak, dizzy, nauseous, headache • Rapid, irregular pulse • Dry, hot, flushed skin

  7. Hypothermia- lowered body temperature • Begins with shivering • Mental confusion, lethargy, loss of reflexes, loss of consciousness • Organs shut down • Core can only withstand a drop of a few degrees • Extremities can withstand drops of 20-30F below normal • Must warm gradually to avoid disrupting respiratory and cardiovascular functioning

  8. Wound Healing • Inflammation is a response to injury or stress • Blood vessels dilate and become permeable • Fluids leak into damaged tissue • Tissue gets more nutrients and oxygen • Skin becomes reddened, swollen, warm and painful • Shallow cuts • Epithelial cells divide more rapidly • Newly formed cells fill gap

  9. Deep cuts • Blood vessels break and form clots • Tissue fluids seep in and dry • Clotted blot and dried fluids for a scab to protect wound • Epithelial cells bridge the wound and fibroblasts secrete fibers to bind the wound • Blood vessels extend beneath scab • Phagocytes remove deal cells • Damaged tissues replace • Scab falls off • Scars form if excess collagenous fibers formed above the normal epidermal surface

  10. Burns • 1st degree (superficial partial-thickness) burn • Only affects epidermis • Skin becomes warm and reddened • Mild edema • Tender • Surface layer may peel • No scarring

  11. 2nd degree (deep partial-thickness) burn • Destroys epidermis and some underlying dermis • Fluid accumulates beneath epidermal cells to form blisters • Areas becomes moist and firm • Color varies from dark red to waxy white • Exposure to hot objects, liquids, flames, clothes • Stem cells divide and differentiate during healing • Low risk of scarring

  12. 3rd degree (full-thickness) burn • Destroys epidermis, dermis and accessory structures of skin • Skin is dry and leathery • Red to black to white in color • Results from immersion in hot liquids, prolonged exposure to hot objects, flames or chemicals • Spontaneous healing of epithelial cells inward from burn margins • May need grafting or temporary membrane covers • Extensive scarring

  13. Aging • Aging affects: • skin appearance • temperature regulation • vitamin D formation • Epidermis thins over time • Cell cycle slows • Cells grow larger, more irregular in shape and fewer • Scaly skin results from changes in chemical bonding • Age spots result from oxidation of fats in apocrine and eccrine glands

  14. Wrinkling and sagging of skin • Dermis reduces and shrinks • Fat loss from subcutaneous layer • Wound healing is delayed • Fewer fibroblasts • Drier skin • Decreased oil from sebaceous glands

  15. Whitening/graying of hair • Slowed melanin production • Thinning hair • Slower hair growth • Decrease in hair follicles • Hard, dull nails • Decreased blood supply to nail bed • Decrease in pain and pressure sensitivity

  16. Decreased ability to control temperature • Number of sweat glands decreases • Ability to shiver declines • Blood vessels in deeper layers decrease • Decreased ability to direct blood flow to interior • Paler complexion • Fewer vessels in skin • Pressure Sores • Less blood vessels, different distribution • Decreased circulation • Decreased absorption of calcium • Less vitamin D production

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