Introduction to the Integumentary System

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Introduction to the Integumentary System. The integument is the largest system of the body 16% of body weight 1.5 to 2 m 2 in area The integument is made up of two parts ______________________ membrane (skin) Accessory structures (hair, nails, exocrine glands). - PowerPoint PPT Presentation

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  • Introduction to the Integumentary SystemThe integument is the largest system of the body16% of body weight1.5 to 2 m2 in areaThe integument is made up of two parts______________________ membrane (skin)Accessory structures (hair, nails, exocrine glands)

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Introduction to the Integumentary SystemFig 51

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  • Introduction to the Integumentary SystemOriginEctodermCells that respond to FGF2 turn into nervous tissue. Cells that dont turn into skinConnectionsCardiovascular systemBlood vessels in the papillary layer of the dermisNervous systemSensory receptors for pain, touch, and temperature

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Introduction to the Integumentary SystemFunctions of SkinProtects underlying tissues and organs (U.V., invaders)Excretes salts, water, and organic wastes (glands)Maintains body temperature (insulation and evaporation)Synthesizes vitamin D3 Stores lipidsDetects touch, pressure, pain, and temperature

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • EpidermisThe most abundant cells of the epidermis are ____________.Contain large amounts of keratinEpidermis is avascular stratified squamous epitheliumNutrients and oxygen diffuse from capillaries in the dermisThin Skin: Covers most of the body Has four layers of keratinocytes Thick Skin: Covers the palms of the hands and soles of the feetHas five layers of keratinocytesLacks hair and sebaceous glands

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Epidermis

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  • EpidermisStratum Germinativum (Stratum Basale)The germinative layerHas many germinative (stem) cells or basal cellsIs attached to basal lamina by hemidesmosomesForms a strong bond between epidermis and dermisForms ____________________(e.g., fingerprints) Dermal papillae (tiny mounds)Increase the area of basal laminaStrengthen attachment between epidermis and dermis

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • EpidermisFig 5-4Fig. 5-2Dermal papilla: Tiny mounds that (1) increase the area of the basal lamina and (2) strengthen the attachment between the epidermis and the dermis

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • EpidermisSpecialized Cells of Stratum Germinativum______________________(1% of cells in the skin)Found in hairless skin (sensory function)Respond to touch (trigger nervous system)______________________ (3% of cells in the skin)Contain the pigment melaninScattered throughout stratum germinativum

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • EpidermisStratum SpinosumThe spiny layerProduced by division of stratum germinativumEight to ten layers of keratinocytes bound by desmosomesCells shrink until cytoskeletons stick out (spiny)Continue to divide, increasing thickness of epitheliumContain dendritic (______________) cells, active in immune response

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  • EpidermisStratum GranulosumThe grainy layer Cells stop dividing, produce protein fibers, dehydrate, and dieKeratin: a tough, fibrous protein makes up hair and nailsKeratohyalin :dense granulescross-link keratin fibers

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • EpidermisStratum LucidumThe clear layerFound only in thick skinCovers stratum granulosum

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  • EpidermisStratum CorneumThe horn layerExposed surface of skin 15 to 30 layers of keratinized cellsWater resistantShed and replaced every 2 weeks

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  • EpidermisKeratinizationThe formation of a layer of dead, protective cells filled with keratinOccurs on all exposed skin surfaces except eyesSkin life cycleIt takes 1530 days for a cell to move from stratum germinativum to stratum corneum

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Dandruff is caused by excessive shedding of cells from the outer layer of skin in the scalp. Thus dandruff is composed of cells from which epidermal layer?Stratum germinativumStratum spinosumStratum corneumStratum granulosum

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Skin ColorSkin color is influenced byTwo pigments ______________________:orange-yellow pigmentfound in orange vegetablesaccumulates in epidermal cells and fatty tissues of the dermiscan be converted to vitamin A______________________:yellow-brown or black pigmentproduced by melanocytes from tyrosine in the stratum germinativumstored in transport vesicles (melanosomes)transferred to keratinocytesBlood circulation (red blood cells)

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Skin ColorFig 5-5(contains melanin)(in melanosome)

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  • Skin ColorFunction of MelanocytesMelanin protects skin from sun damageUltraviolet (UV) radiationCauses DNA mutations and burns that lead to cancer and wrinklesProduction of cholecalciferol (Vit. D3) within epidermal cellsStimulates secretion of melanocyte stimulating hormone from keratinocytes (this gives you a tan)Skin color depends on melanin production (bigger melanosomes), ____________ number of melanocytes

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  • Skin ColorLocalized differences in rates of melanin production by melanocytes:Freckles: Small pigmented areas with irregular borders on relatively pale skin.Most abundant on surfaces with greater exposure to the sun (e.g., face).Lentigos:Similar to freckles, but have regular borders and contain abnormal melanocytes.Senile lentigos (liver spots/age spots): Variable pigmented areas on sun-exposed skin in older individuals with pale skin.

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  • Skin ColorCapillaries and Skin ColorOxygenated red blood contributes to skin color Blood vessels dilate from heat, skin reddensBlood flow decreases, skin palesCyanosisBluish skin tintCaused by severe reduction in blood flow or oxygenation

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  • Skin ColorIllness and Skin ColorJaundiceBuildup of bile produced by liverYellow color (i.e., yellow pigment accumulates in body fluids)Addison diseaseA disease of the pituitary glandSkin darkening (i.e., secretion of large qunatities of ACTH, a hormone structurally similar to MSH)Vitiligo (1% of population)Loss of melanocytes (attacked by lymphocytes)Loss of color

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  • Skin CancerBasal cell carcinoma = most common.Squamous cell carcinomas = restricted to areas of sun-exposed skin.

    Malignant melanomas = metastasize through the lymphatic system.A = AsymmetryB = BorderC = ColorD = Diameter

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Why does the skin of a fair-skinned person appear red during exercise in hot weather?1. Sunlight stimulates erythrocyte production in skin. 2. Blood is diverted to the superficial dermis to eliminate heat.3. Sunlight bleaches fair skin, allowing blood to be seen.4. Heat stimulates cutaneous blood vessels, causing leaks.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Vitamin D3Vitamin D3Epidermal cells in s. spinosum and s. basale produce cholecalciferol (vitamin D3)In the presence of UV radiationLiver and kidneys convert vitamin D3 into calcitriolTo aid absorption of calcium and phosphorusEssential for bone maintenance and growthInsufficient vitamin D3Can cause __________________ in children and osteomalacia in adults.

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  • Vitamin D3Fig 5-7

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  • In some cultures, women must be covered completely, except for their eyes, when they go outside. Explain why these women exhibit a high incidence of problems with their bones.1. UV light prevents calcium deposition in bones.2. Melanin production is necessary for bone growth.3. Cloth prevents oxygen from diffusing into skin and bones.4. UV light is necessary to produce the hormone cholecalciferol (vitamin D3).

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Epidermal Growth Factor (EGF)Is a powerful peptide growth factor Is produced by glands (salivary and duodenum)Is used in laboratories to grow skin graftsFunctions of EGFPromotes division of germinative cellsAccelerates keratin productionStimulates epidermal repairStimulates glandular secretion

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The DermisThe DermisIs located between epidermis and subcutaneous layerAnchors epidermal accessory structures (hair follicles, sweat glands) Has two componentsOuter papillary layer Deep reticular layer

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The DermisThe Papillary LayerConsists of areolar tissueContains smaller capillaries, lymphatics, and sensory neuronsHas dermal papillae projecting between epidermal ridgesThe Reticular LayerConsists of dense irregular connective tissueContains larger blood vessels, lymph vessels, and nerve fibersContains collagen and elastic fibersContains connective tissue proper

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The DermisDermatitisAn inflammation of the papillary layerCaused by infection, radiation, mechanical irritation, or chemicals (e.g., poison ivy)Characterized by itch or pain (due to abundance of sensory receptors in skin.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The DermisDermal Strength and ElasticityPresence of two types of fibersCollagen fibers:very strong, resist stretching but bend easilyprovide flexibilityElastic fibers:permit stretching and then recoil to original lengthlimit the flexibility of collagen fibers to prevent damage to tissue

    Properties of flexibility and resilienceSkin turgor:

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Skin Damage (dermal level)Sagging and wrinkles (reduced skin elasticity) are caused by:Dehydration (loss of skin turgor)AgeHormonal changesUV exposureStretch Marks (Thickened tissue resulting from excessive stretching of skin due to):PregnancyWeight gain/lossNote: Tetinoin (Retin-A), a derivative of Vit. A, increases blood flow to dermis and stimulates dermal repair leading to a decrease in wrinkles.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The DermisLines of CleavageCollagen and elastic fibers in the dermis Are arranged in parallel bundlesResist force in a specific directionLines of cleavage establish important patternsA parallel cut remains shut, heals wellA cut across (right angle) pulls open and scars Fig 5.8

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • The HypodermisThe __________________ layer or hypodermis Lies below the integumentIs connected to the reticular layer of integument by connective tissue fibersIs made of elastic areolar and adipose tissues(Subcutaneous fat deposits can be reduced by lipoplasty)Has few capillaries and no vital organs (only the superficial region or reticular layer of the dermis has large arteries and veins.Is the site of subcutaneous injections using hypodermic needles

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • HairHair, hair follicles, sebaceous glands, sweat glands, and nailsAre integumentary accessory structuresAppendages of the skin that represent specializations of keratinocytes that extend from the connective tissue to the skinAre derived from embryonic epidermis Are located in dermisProject through the skin surface

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • HairThe Hair FollicleIs located deep in dermisProduces nonliving hairs Is wrapped in a dense connective tissue sheathBase is surrounded by sensory nerves (root hair plexus)

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  • HairHair Shaft StructureMedullaThe central core CortexThe middle layer CuticleThe surface layer

    Cross-Section Through a Hair FollicleFig 5.10

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  • HairThe human body is covered with hair, exceptPalmsSolesLipsPortions of external genitaliaFunctions of HairProtects and insulatesGuards openings against particles and insectsIs sensitive to very light touch

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  • HairAccessory Structures of Hair_______________________ Involuntary smooth muscle Causes hairs to stand upProduces goose bumps________________________ Lubricate the hairControl bacteria

    Fig 5.10

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  • HairHair Color: Produced by melanocytes at the hair papillaDetermined by genesAlopecia Areata: Ability to produce hair is gone (2% of population)Due to immune system attack on the hair folliclesMale Pattern Baldness:Hair growth is inhibited by testosterone receptor alterations (50% of men over 50)Rogaine can stimulate production of growth factors that stimulate weakened hair follicles to create larger amounts of hair

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Which two events are possible results of the contraction of the arrector pili muscle?1.Goose bumps/release of sebum2. Sweating/contraction of underlying muscles3. Goose bumps/localized increase in blood flow4. Localized pallor/release of sebum

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Sebaceous Glands and Sweat GlandsExocrine Glands in SkinSebaceous glands (oil glands)Simple branched alveolar glands are associated with hair folliclesHolocrine glandsSecrete sebum (lipids and other stuff that lubricate and protect the epidermis while inhibiting bacteria)Sweat glandsTwo types: apocrine glands and merocrine (eccrine) glandsWatery secretions

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Clinical CorrelationsFolliculitis:Local inflammation of hair follicle as a result of a bacterial infection.Furuncle or boil:Abscess from blockage of a glands duct.Acne:Due to increased concentration of sex hormones during puberty.Seborrheic dermatitis:Inflammation around abnormally active sebaceous glandsSebaceous...

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