5-1 Tortora & Grabowski 9/e 2000 JWS This powerpoint presentation has been adapted from Life 4e-Lewis, Gaffin, Hoefnagels and Parker. Publishers- McGraw-Hill 1998 and Principles of Anatomy and Physiology,Tortora and Grabowski. Publishers- John Wiley & sons, Inc. 2000

5-2 Tortora & Grabowski 9/e 2000 JWS Chapter 5 The Integumentary System Skin and its accessory structures –structure –function –growth and repair –development –aging –disorders

5-3 Tortora & Grabowski 9/e 2000 JWS General Anatomy The largest organ and is composed of all 4 tissue types On average: 22 square feet 1-2 mm thick Weight 10 lbs.

5-4 Tortora & Grabowski 9/e 2000 JWS Overview 2 Major layers of skin –epidermis is epithelial tissue only –dermis is layer of connective tissue, nerve & muscle Subcutaneous tissue (subQ or hypodermis) is layer of adipose & areolar tissue –subQ = subcutaneous injection –intradermal = within the skin layer

5-5 Tortora & Grabowski 9/e 2000 JWS Overview of Epidermis Stratified squamous epithelium Contains no blood vessels/avascular 4 types of cells 5 distinct strata (layers) of cells

5-6 Tortora & Grabowski 9/e 2000 JWS Cell types of the Epidermis Keratinocytes--90% –produce keratin Melanocytes % –produces melanin pigment –melanin transferred to other cells with long cell processes Langerhan cells –from bone marrow –provide immunity Merkel cells –in deepest layer –form touch receptor with sensory neuron

5-7 Tortora & Grabowski 9/e 2000 JWS Layers (Strata) of the Epidermis Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale

5-8 Tortora & Grabowski 9/e 2000 JWS Stratum Basale Deepest single layer of cells Also called stratum germinativum Combination of merkel cells, melanocytes, keratinocytes & stem cells that divide repeatedly Cells attached to each other & to basement membrane by cell junctions

5-9 Tortora & Grabowski 9/e 2000 JWS Stratum Spinosum 8 to 10 cell layers held together by cell junctions During preparation for microscopic examination, cells shrink and look spiny Melanin taken in by phagocytosis from nearby melanocytes

5-10 Tortora & Grabowski 9/e 2000 JWS Stratum Granulosum layers of flat dying cells Show nuclear degeneration

5-11 Tortora & Grabowski 9/e 2000 JWS Stratum Lucidum Found only in thick skin on palms & soles of feet Three to five layers of clear, flat, dead cells Contains precursor of keratin

5-12 Tortora & Grabowski 9/e 2000 JWS Stratum Corneum 25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids Continuously shed Barrier to light, heat, water, chemicals & bacteria Friction stimulates callus formation

5-13 Tortora & Grabowski 9/e 2000 JWS Keratinization & Epidermal Growth Stem cells divide to produce keratinocytes As keratinocytes are pushed up towards the surface, they fill with keratin 4 week journey unless outer layers removed in abrasion Hormone EGF (epidermal growth factor) can speed up process Psoriasis = chronic skin disorder –cells shed in 7 to 10 days instead of 28 :flaky, greasy scales –abnormal keratin produced

5-14 Tortora & Grabowski 9/e 2000 JWS Skin Grafts New skin can not regenerate if stratum basale and its stem cells are destroyed Skin graft is covering of wound with piece of healthy skin –autograft from self –isograft from twin –autologous skin transplantation of patients skin grown in culture

5-15 Tortora & Grabowski 9/e 2000 JWS Dermis Connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages, muscle (arrector pili) & fat cells Contains hair follicles, glands, nerves & blood vessels Major regions of dermis –papillary region –reticular region

5-16 Tortora & Grabowski 9/e 2000 JWS Papillary Region Top 20% of dermis Composed of loose CT & elastic fibers Finger like projections called dermal papillae Functions –anchors epidermis to dermis –contains capillaries that service epidermis –contains Meissners corpuscles (touch) & free nerve endings (pain and temperature)

5-17 Tortora & Grabowski 9/e 2000 JWS Reticular Region Dense irregular connective tissue Contains interlacing collagen and elastic fibers Packed with oil glands, sweat gland ducts, fat, muscle (arrector pili) & hair follicles Provides strength, extensibility & elasticity to skin –stretch marks are dermal scars from extreme stretching Epidermal ridges form in fetus (fetal timing) as epidermis conforms to dermal papillae –fingerprints are left by sweat glands open on ridges –increase grip of hand

5-18 Tortora & Grabowski 9/e 2000 JWS Skin Color Pigments (1) Melanin produced in epidermis by melanocytes –same number of melanocytes in everyone, but differing amounts of pigment produced –results vary from yellow to tan to black color –melanocytes contain enzyme tyrosinase that converts the amino acid tyrosine to melanin UV (A/B) in sunlight increases melanin production Clinical observations –freckles or liver spots = melanocytes in a patch –albinism = inherited lack of tyrosinase; no pigment –vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches

5-19 Tortora & Grabowski 9/e 2000 JWS Skin Color Pigments (2) Carotene in dermis –yellow-orange pigment (precursor of vitamin A) –found in (fat) adipocytes of stratum corneum & dermis Hemoglobin –red, oxygen-carrying pigment in blood cells –if other pigments are not present, epidermis is translucent so pinkness will be evident

5-20 Tortora & Grabowski 9/e 2000 JWS Skin Color as Diagnostic Clue Jaundice –yellowish color to skin and whites of eyes –buildup of yellow bilirubin in blood from liver disease Cyanotic –bluish color to nail beds and skin (should be pink) –hemoglobin depleted of oxygen looks purple-blue Erythema –redness of skin due to vasodilation of capillaries in dermis – during inflammation, infection, allergy or burns

5-21 Tortora & Grabowski 9/e 2000 JWS Accessory Structures of Skin Epidermal derivatives Epidermal cells sink inward during development to form: –hair –oil glands –sweat glands –nails

5-22 Tortora & Grabowski 9/e 2000 JWS Structure of Hair Shaft -- visible –medulla, cortex & cuticle –Root -- below the surface Follicle surrounds root (same #/in. 2 in all primates/genders) By birth all follicles present –external root sheath –internal root sheath –base of follicle is bulb blood vessels germinal cell layer

5-23 Tortora & Grabowski 9/e 2000 JWS Hair Related Structures A rrector pili –smooth muscle in dermis contracts with cold or fear. –forms goosebumps as hair is pulled vertical Hair root plexus –detect hair movement

5-24 Tortora & Grabowski 9/e 2000 JWS Hair Growth Growth cycle = growth stage & resting stage Growth stage – lasts for 2 to 6 years for scalp, varies in different body locations ( i.e.10 weeks for eyebrow, 6 weeks for eye lash) – matrix cells at base of hair root divide producing more cells = length Resting stage – lasts for 3 months –matrix cells inactive & follicle atrophies Old hair falls out as growth stage begins again –normal hair loss is 70 to 100 hairs per day

5-25 Tortora & Grabowski 9/e 2000 JWS Hair Color Result of melanin produced in melanocytes in hair bulb Dark hair contains true melanin Blond and red hair contain melanin with iron and sulfur added Graying hair is result of decline in melanin production White hair has air bubbles in the medullary shaft

5-26 Tortora & Grabowski 9/e 2000 JWS Functions of Hair P revents heat loss Decreases sunburn Eyelashes help protect eyes Touch receptors (hair root plexus) senses slight touch

5-27 Tortora & Grabowski 9/e 2000 JWS Glands of the Skin Specialized exocrine glands found in dermis Sebaceous (oil) glands Sudiferous (sweat) glands Ceruminous (wax) glands Mammary (milk) glands

5-28 Tortora & Grabowski 9/e 2000 JWS Sebaceous (oil) glands Secretory portion in the dermis Most open onto hair shafts Sebum –combination of cholesterol, proteins, fats & salts –keeps hair and skin from soft & pliable –inhibits growth of bacteria & fungi(ringworm) Acne –bacterial inflammation and infection of glands –Oil production stimulated by hormones(more so by androgens than estrogen/progesterone) at puberty

5-29 Tortora & Grabowski 9/e 2000 JWS Acne treatment OTC- unclog sebaceous pores, reduce bacteria,remove superficial skin layer antibiotics- tetracycline kills bacteria accutane- reduce sebaceous gland

5-30 Tortora & Grabowski 9/e 2000 JWS Sudoriferous (sweat) glands Eccrine (sweat) glands –2-5 million: most areas of skin (palm, sole highest concentration 5-10x more than elsewhere insensible) –regulate body temperature with perspiration –H 2 O, NaCl,NW,AA,sugars,vit. C,lactic acid Apocrine (sweat) glands –armpit and pubic region –secretions more viscous and aromatic –Fear/sexual arousal

5-31 Tortora & Grabowski 9/e 2000 JWS Ceruminous glands Modified sweat glands produce waxy secretion in ear canal Cerumin contains secretions of oil and wax glands Helps form barrier for entrance of foreign bodies Impacted cerumen may reduce hearing

5-32 Tortora & Grabowski 9/e 2000 JWS Nails Tightly packed, keratinized cells Nail body is pink due to underlying capillaries and oxygenated blood Lunula appears white due to thickened stratum basale (ct) in that area masking capillaries Cuticle (eponychium) is stratum corneum Nail matrix deep to the nail root is the region from which the nail growth occurs Growth is 1mm per week--faster in summer & on most-used hand

5-33 Tortora & Grabowski 9/e 2000 JWS Structure of Nails Tightly packed keratinized cells Nail body –visible portion pink due to underlying capillaries and oxygenated blood –free edge appears white Nail root –buried under skin layers –lunula is white due to thickened stratum basale Eponychium (cuticle) –stratum corneum layer

5-34 Tortora & Grabowski 9/e 2000 JWS Nail Growth Nail matrix below nail root produces growth Cells transformed into tightly packed keratinized cells 1 mm per week

5-35 Tortora & Grabowski 9/e 2000 JWS Types of Skin Thin skin –covers most of body –thin epidermis (.1 to.15 mm.) that lacks stratum lucidum –lacks epidermal ridges, has fewer sweat glands and sensory receptors Thick skin –only on palms and soles –thick epidermis (.6 to 4.5 mm.) with distinct stratum lucidum & thick stratum corneum –lacks hair follicles and sebaceous glands

5-36 Tortora & Grabowski 9/e 2000 JWS General Functions of the Skin Regulation of body temperature Protection against physical trauma and radiation Sensory receptors Excretion and and some absorption Synthesis of vitaminD Water balance Blood pressure regulation- blood reservoirs Sexual/social consequences

5-37 Tortora & Grabowski 9/e 2000 JWS Thermoregulation Releasing of sweat onto the skin –perspiration & its evaporation lowers body temperature Adjusting flow of blood to the body surface –in moderate exercise, more blood brought to surface helps lower temperature –with extreme exercise, blood is shunted to muscles and body temperature rises Shivering and constriction of surface vessels –raise internal body temperature as needed

5-38 Tortora & Grabowski 9/e 2000 JWS Protection Physical, chemical,radiation and biological barrier –tight cell junctions prevent bacterial invasion –Sebum and lipids reduces evaporation –pigment give limited protection against UV damage to cells especially DNA, protein fibers –Part of immune system

5-39 Tortora & Grabowski 9/e 2000 JWS Cutaneous Sensations Touch, temperature, pressure, vibration, tickling and some pain sensations arise from the skin.

5-40 Tortora & Grabowski 9/e 2000 JWS Excretion and Absorption Only a minor role is played by the skin 400 mL of water evaporates from it daily Small amounts salt, CO 2, ammonia and urea are excreted Lipid soluble substances can be absorbed through the skin –vitamins A, D, E and K –acetone and dry-cleaning fluid, lead, mercury, arsenic, molecules in poison ivy and poison oak

5-41 Tortora & Grabowski 9/e 2000 JWS Transdermal Drug Administration Method by which drugs in a patch enter the body Drug absorption most rapid in areas where skin is thin (scrotum, face and scalp) Examples –nitroglycerin (prevention of chest pain from coronary artery disease) –scopolamine ( motion sickness) –estradiol (estrogen replacement therapy) –nicotine (stop smoking alternative)

5-42 Tortora & Grabowski 9/e 2000 JWS Synthesis of Vitamin D Sunlight activates a precursor to vitamin D supplemented in all milk. Enzymes in the liver and kidneys transform that molecule into calcitriol (most active form of vitamin D) Necessary vitamin for absorption of calcium from diet into blood of the gastrointestinal tract

5-43 Tortora & Grabowski 9/e 2000 JWS Blood pressure- vasodilation of dermal vessels lowers systemic blood pressure. vasoconstriction of dermal vessels raises systemic blood pressure.

5-44 Tortora & Grabowski 9/e 2000 JWS Clear complexion increases chance of social (perception by self and others) and sexual success.

5-45 Tortora & Grabowski 9/e 2000 JWS Epidermal Wound Healing Abrasion or minor burn Basal cells migrate across the wound Contact inhibition with other cells stops migration Epidermal growth factor stimulates cell division Full thickness of epidermis results from further cell division

5-46 Tortora & Grabowski 9/e 2000 JWS Deep Wound Healing If an injury reaches dermis, healing occurs in 4 phases –inflammatory phase has clot unite wound edges and WBCs arrive from dilated and more permeable blood vessels –migratory phase begins the regrowth of epithelial cells and the formation of scar tissue by the fibroblasts –proliferative phase is a completion of tissue formation –maturation phase sees the scab fall off Scar formation –hypertrophic scar remains within the boundaries of the original wound –keloid scar extends into previously normal tissue collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in color

5-47 Tortora & Grabowski 9/e 2000 JWS Phases of Deep Wound Healing Which phases have been left out of this illustration?

5-48 Tortora & Grabowski 9/e 2000 JWS Age Related Structural Changes Collagen fibers decrease in number & stiffen Elastic fibers become less elastic Fibroblasts decrease in number Langerhans cells and macrophages decrease in number and become less-efficient phagocytes Oil glands shrink and the skin becomes dry Walls of blood vessels in dermis thicken so decreased nutrient availability leads to thinner skin as subcutaneous fat is lost

5-49 Tortora & Grabowski 9/e 2000 JWS Photodamage Ultraviolet light (UVA and UVB) both damage the skin Acute overexposure causes sunburn DNA damage in epidermal cells can lead to skin cancer UVA produces oxygen free radicals that damage collagen and elastic fibers and lead to wrinkling of the skin

5-50 Tortora & Grabowski 9/e 2000 JWS Skin Cancer Over 1 million cases diagnosed per year in U.S. 3 common forms of skin cancer –basal cell carcinoma 800,000 (rarely metastasize) –squamous cell carcinoma 200,000 (may metastasize) –malignant melanomas 40,000-50,000 (metastasize rapidly7,300 die first year) most common cancer in young women arise from melanocytes ----life threatening key to treatment is early detection watch for changes in symmetry, border, color and size risks factors include-- skin color, sun exposure, family history, age and immunological status Paba, sunblocks-zinc oxide best!

5-51 Tortora & Grabowski 9/e 2000 JWS Cancer Risk Factors Skin type Sun exposure Family history Age Immunological status

5-52 Tortora & Grabowski 9/e 2000 JWS Burns Destruction of proteins and cell necrosis –chemicals, electricity, heat, –Radiation:uv, x-ray, gamma, etc. Problems that result –shock due to water, plasma and plasma protein loss –circulatory & kidney problems from loss of plasma –bacterial infection –Inabilty to thermoregulate –Scarring, little to no elasticity with scarred skin

5-53 Tortora & Grabowski 9/e 2000 JWS Types of Burns First-degree –only epidermis (ex. sunburn) Second-degree burn –destroys entire epidermis & part of dermis (ex. severe sunburn) –fluid-filled blisters separate epidermis & dermis –epidermal derivatives are not damaged –heals without grafting in 3 to 4 weeks & may scar Third-degree or full-thickness –destroy epidermis, dermis, epidermal derivatives and perhaps muscle/bone –damaged area is numb due to loss of sensory nerves

5-54 Tortora & Grabowski 9/e 2000 JWS Tissue Repair: Restoring Homeostasis Worn-out, damaged tissue must be replaced Fibrosis = replacement with stromal connective tissue cells (scar formation) Regeneration = replacement with original cell types (parenchymal cells) –some cell types can divide (liver & endothelium) –some tissues contain stem cells that can divide bone marrow, epithelium of gut & skin –some cell types can not divide & are not replaced muscle and nervous tissue

5-55 Tortora & Grabowski 9/e 2000 JWS Important Clinical Terminology Regeneration versus fibrosis Granulation tissue –very actively growing connective tissue Adhesions –abnormal joining of tissue –occurs after surgery or inflammation

5-56 Tortora & Grabowski 9/e 2000 JWS Conditions Affecting Tissue Repair Nutrition –adequate protein for structural components –vitamin C production of collagen and new blood vessels Proper blood circulation –delivers O 2 & nutrients & removes fluids & bacteria With aging – collagen fibers change in quality –elastin fibers fragment and abnormally bond to calcium –cell division and protein synthesis are slowed