2 Most Important Function PROTECTION is the most important function of the integumentary system
3 5 Major Functions Serving as a barrier against infection and disease Helping to regulate body temperatureRemoving waste products from the bodyProviding protection against Ultraviolet radiation from the sunProducing vitamin D
4 Layers of Skin Epidermis Dermis Subcutaneous layer beneath dermis not part of skin
6 Epidermis lacks blood vessels keratinized thickest on palms and soles ( mm)melanocytes provide melaninrests on basement membranestratified squamous
7 Epidermis Outermost layer of the skin Its layers are made of Mostly DEAD CELLS.Most of the cells of the epidermis undergo rapid cell division (MITOSIS).As new cells are produced, they push older cells to the surface of the skin. The older cells become flattened, lose their cellular contents and begin making KERATIN.
8 KeratinA TOUGH FIBROUS PROTEIN that FORMS THE BASIC STRUCTURE OF HAIR, NAILS, AND CALLUSES.Eventually, the Keratin-producing Cells (KERATINOCYTES) DIE AND FORM A TOUGH, FLEXIBLE WATERPROOF COVERING ON THE SURFACE OF THE SKIN. Our thickest Epidermis is on palms of hands and soles of feet.OUTER LAYER OF DEAD CELLS IS SHED OR WASHED AWAY ONCE EVERY 14 TO 28 DAYS.
18 Problems in Temperature Regulation Hyperthermia – abnormally high body temperatureHypothermia – abnormally low body temperature
19 Regulating body temperature The dermis helps us to control our body temperature:On a cold day when the body needs to conserve heat, the blood vessels in the dermis NARROW.On hot days, the blood vessels WIDEN, warming the skin and increasing heat loss.Tiny muscle fibers attach to hair follicles contract and pull hair upright when you are cold or afraid, producing what is commonly called Goose Bumps.
20 Skin Color Genetic Factors Physiological Factors varying amounts of melaninvarying size of melanin granulesalbinos lack melaninPhysiological Factorsdilation of dermal blood vesselsconstriction of dermal blood vesselsaccumulation of carotenejaundiceEnvironmental FactorssunlightUV light from sunlampsX raysdarkens melanin
21 Skin ColorThe Epidermis contains MELANOCYTES, cells that produce MELANIN, a dark brown pigment.Both light skinned and dark skinned people have roughly the same number of melanocytes, the difference in our skin color is caused by the amount of melanin the melanocytes produce and distribute.The amount of melanin produced in skin depends on TWO factors - Heredity and the Length of Time the Skin is Exposed to Ultraviolet Radiation (Tanning).
22 Skin ColorMelanin is important for protection, by absorption of Ultraviolet Radiation from the sun. All people, but especially people with light skin, need to minimize exposure to the sun and protect themselves from its Ultraviolet Radiation, which can damage DNA in skin cells and lead to deadly forms of skin cancer such as MELANOMA CANCER.THERE ARE NO BLOOD VESSELS IN THE EPIDERMIS, WHICH IS WHY A SMALL SCRATCH WILL NOT CAUSE BLEEDING.
29 Healing of Burns First degree burn – superficial partial-thickness Second degree burn – deep partial-thickness-burns some dermis-fluid escapes from capillaries and builds upunder epidermis causing blisteringThird degree burn – full-thicknessautograft (own skin transfer)homograft (person to person [cadaver])various skin substitutes
30 First Degree BurnOnly the superficial epidermis is burned, and is painful but not blistered.Causes death of epidermal cells.
31 Second Degree Burn Deeper layers of epidermis are effected And touches dermisCould have inflammation, blisters, and the burned skin is often painful.
32 Third Degree BurnThe entire epidermis is charred or burned away, and the burn may extend into the dermis. Often such a burn is not painful at first, if the receptors in the dermis have been destroyed.
33 Life Span Changes Melanin production slows Skin becomes scaly Hair thinsNumber of hair follicles decreaseNail growth becomes impairedSensory receptors declineBody temperature unable to be controlledDiminished ability to activate Vitamin DSkin becomes scalyAge spots appearEpidermis thinsDermis becomes reducedLoss of fatWrinklingSaggingSebaceous glands secrete less oil
34 Clinical Application Acne Vulgaris most common skin disorder sebum and epithelial cells clog glandsproduces whiteheads and blackheadsanaerobic bacteria trigger inflammation (pimple)largely hormonally inducedandrogens stimulate sebum productiontreatments include antibiotics, topical creams, birth control pills
35 Common Skin DisordersIf the Ducts of Oil Glands become clogged with excessive amounts of Sebum, Dead Cells, and Bacteria, the Skin disorder ACNE can result.When first wearing new shoes, the skin of the foot may be subject to friction. This will separate layers of Epidermis, or separate the Epidermis from the Dermis, and tissue fluid may collect, causing a BLISTER.If the skin is subjected to pressure, the rate of mitosis will increase and create a thicker Epidermis; we call this a CALLUS.