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Anatomy of the Skin.

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Presentation on theme: "Anatomy of the Skin."— Presentation transcript:

1 Anatomy of the Skin

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 temperature Removing waste products from the body Providing protection against Ultraviolet radiation from the sun Producing vitamin D

4 Layers of Skin Epidermis Dermis Subcutaneous layer beneath dermis
not part of skin

5 Subcutaneous Layer hypodermis loose connective tissue adipose tissue
insulates major blood vessels

6 Epidermis lacks blood vessels keratinized
thickest on palms and soles ( mm) melanocytes provide melanin rests on basement membrane stratified 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 Keratin A 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.

9 Epidermis Layers of Epidermis stratum corneum stratum lucidum
stratum granulosum stratum spinosum stratum basale

10 5 Layers of Epidermis From superficial to most deep Stratum corneum
Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale

11 Dermis on average 1.0-2.0mm thick
contains dermal papillae (fingerprints) binds epidermis to underlying tissues irregular dense connective tissue muscle cells nerve cell processes specialized sensory receptors blood vessels hair follicles glands

12 Hair Follicles epidermal cells tube-like depression
extends into dermis hair root hair shaft hair papilla dead epidermal cells melanin arrector pili muscle

13 Nails protective coverings nail plate nail bed lunula

14 Sebaceous Glands usually associated with hair follicles
holocrine glands secrete sebum (oil) absent on palms and soles

15 Sweat Glands sudoriferous glands widespread in skin
originates in deeper dermis or hypodermis eccrine glands apocrine glands ceruminous glands mammary glands

16 Sensory structures of Dermis
Deep touch/pressure: Pacinian corpuscles Light touch/pressure: Meisner’s corpuscles Warm temperature: Free nerve endings Cold temperature: Free nerve endings Pain: Free nerve endings

17 Regulation of Body Temperature

18 Problems in Temperature Regulation
Hyperthermia – abnormally high body temperature Hypothermia – 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 melanin varying size of melanin granules albinos lack melanin Physiological Factors dilation of dermal blood vessels constriction of dermal blood vessels accumulation of carotene jaundice Environmental Factors sunlight UV light from sunlamps X rays darkens melanin

21 Skin Color The 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 Color Melanin 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.

23 Melanocyte

24 Melanocyte

25 Melanoma                                                     

26 Actinic Keratosis Caused by sun damage. Can lead to
squamous cell carcinoma.

27 EVOLUTION OF SKIN COLOR
Balance between Need for protection against UV radiation which Causes skin cancer Destroys folate (vitamin B) Need for UV to produce vitamin D for calcium absorption

28 Healing of Cuts

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 up under epidermis causing blistering Third degree burn – full-thickness autograft (own skin transfer) homograft (person to person [cadaver]) various skin substitutes

30 First Degree Burn Only 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 dermis Could have inflammation, blisters, and the burned skin is often painful.

32 Third Degree Burn The 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 thins Number of hair follicles decrease Nail growth becomes impaired Sensory receptors decline Body temperature unable to be controlled Diminished ability to activate Vitamin D Skin becomes scaly Age spots appear Epidermis thins Dermis becomes reduced Loss of fat Wrinkling Sagging Sebaceous glands secrete less oil

34 Clinical Application Acne Vulgaris most common skin disorder
sebum and epithelial cells clog glands produces whiteheads and blackheads anaerobic bacteria trigger inflammation (pimple) largely hormonally induced androgens stimulate sebum production treatments include antibiotics, topical creams, birth control pills

35 Common Skin Disorders If 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.


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