5-* Anatomy and Physiology, Seventh EditionRod R. Seeley Idaho State UniversityTrent D. Stephens Idaho State UniversityPhilip Tate Phoenix CollegeCopyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.Chapter 05Lecture Outline*

5-*Integumentary System

Temperature regulation sweating, constriction of skin pore to keep heat in, change in the flow of blood.ProtectionSensationExcretionImmunityServe as a reservoir of blood because of the extensive networks of blood vessels.Vitamin D production

5-*SKIN AND ITS FUNCTIONS

Structures that are part of the integument

SkinHairNailsGlands5-*

Skin: composed of dermis and epidermis5-*

EpidermisAvascular = no blood vessels; nourished by diffusion from capillaries of the papillary layer of the dermisComposed of cells arranged into layers or strata.Separated from dermis by basement membraneMade up of stratified squamous epithelium and includes four principal types of cells

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5-*Epidermal CellsKeratinocytes: most cells. Produce keratin for strength, joined together by desmosomes.Melanocytes: produce melanin pigment; control skin color.Langerhans cells: come from the bone marrow, relate with helper T-cells in immune response. Easily damaged by UV radiation.Merkels cells: located in stratum basale, attached to keratinocytes by desmosomes, found in the flattened ending of sensory neurons called tactile (Merkel) disc. Can sense touch and light pressure.

Characteristics of the epidermisDesquamate: cells of the deeper layers undergo mitosis; as they move toward the surface, older cells slough offKeratinization: as cells move outward through the layers, they fill with keratin, die and serve as a layer that resists abrasion and forms permeability layerKeratin protein that protects the deeper layer of the skin from injury and microbial invasion. It also waterproofs the skin.

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5-*Epidermal StrataStratum basale (germinitivum)Deepest portion of epidermis and single layer. High mitotic activity due to presence of stem cells that multiply to produce keratinocytes. Stratum spinosumLimited cell division. Desmosomes. Produce lamellar bodies and additional keratin fibers.Stratum granulosumContains keratohyalin (precursor of keratin). In superficial layers nucleus and other organelles degenerate and cell diesStratum lucidumThin, clear zone. Found only in palms and solesStratum corneumMost superficial and consists of cornified cells. Sloughs off after 2 -4 weeks.

5-*Epidermal Layers and Keratinization

Skin: composed of dermis and epidermisDermis. Gives structural strength. C.T. with many fibers, fibroblasts, macrophages. Some adipocytes and blood vessels. Contains nerves, blood vessels, hair follicles, smooth muscles, glands, and lymphatic vessels.Sensory functions: pain, itch, tickle, temperature, touch, pressure, two-point discrimination.5-*

Two Layers of the DermisPapillary. Superficial (outer) 1/5. Areolar with lots of elastic fibers. Dermal papillae, capillary beds. Fingerprints. Whorls of ridges. Touch receptors (aka Meissner's corpuscles), pacinian corpuscles for pressure. free nerve endings sensing pain. Ridges produce fingerprints. Reticular: Deep (inner) 4/5 Dense irregular C.T. Collagen and elastic fibers. Contains some adipose, hair follicles, nerves, oil glands, ducts of sweat glands, heat sensors.5-*

5-*Cleavage (Tension) Lines and StriaeCleavage (tension) lines: elastin and collagen fibers oriented in some directions more than in othersImportant in surgeryIf incision parallel to lines, there is less gapping, faster healing, less scar tissueIf skin is overstretched, striae (stretch marks) occur

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HypodermisDeep to skin, beneath the dermis and epidermis.Consists of loose connective tissue with collagen and elastic fibersTypes of cellsFibroblastsAdipose cellsMacrophages

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Also calledSubcutaneous tissueSuperficial fasciaContains about one-half of bodys fat. Functions asEnergy sourceInsulationPadding or cushion to keep the skin plump.

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Thick and Thin SkinThick skinHas all 5 epithelial strataFound in areas subject to pressure or frictionPalms of hands, fingertips, soles of feetFingerprints and footprints. Papillae of underlying dermis in parallel rowsThin skinMore flexible than thick skinCovers rest of bodyCallus. Increase in number of layers in stratum corneum. When this occurs over a bony prominence, a corn forms.5-*

Skin Color: Pigments5-*

Skin Color: PigmentsDetermined by 3 factors: pigments, blood circulating through the skin, thickness of stratum corneumPigmentsMelanin: provides for protection against UV light. Group of chemicals derived from aa tyrosine. Colored brown to black, may be yellowish or reddishMelanocytes. Processes extend between Keratinocytes. Albinism: deficiency or absence of pigment. Production determined by genetics, hormones, exposure to light5-*

Carotene: yellow pigment. From vegetables. Accumulates in stratum corneum, in adipose cells of dermis, and in hypodermis.Hemoglobin pigment in blood5-*

5-*Skin Color: Blood and Stratum Corneum ThicknessBlood circulating through the skinImparts reddish hue and increases during blushing, anger, inflammationCyanosis: blue color caused by decrease in blood oxygen contentThickness of stratum corneum

Accessory Skin Structures: Hair 5-*

Accessory Skin Structures: Hair Found everywhere on human body except palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toesShaft protrudes above skin surfaceRoot located below surface; base of root is the hair bulbHas 3 concentric layersMedulla: Central axisCortex: Forms bulk of hairCuticle: Forms hair surface5-*

Hair follicleDermal root sheath: part of dermis that surrounds the epithelial root sheathEpithelial root sheath with internal and external parts. Internal part contains stratum basale that may remain after injury and supply a source of new epidermisWhen hairs are pulled out, internal part comes out and is visible as white bulbHair bulbInternal matrix is source of hairDermis projects into bulb and is blood supply

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Hair, cont.5-*

5-*Hair Growth, Color, and MusclesHair GrowthCyclesGrowth and resting stagesGrowth: cells added at base and hair elongates. Average rate is 0.3 mm/dayRest: follicle shortens and holds hair in place. Rest, then hair falls out of follicle. New hair begins.Regular hair loss means hair is being replaced. Permanent hair loss: pattern baldness most common causeHair Color. Caused by varying amounts and types of melanin. Melanin can be black-brown and redMuscles. Arrector pili. Type of smooth muscle. Muscle contraction causes hair to stand on endSkin pushed up by movement of hair follicle

Glands- Sebaceous (Oil)5-*

Accessory Skin Structures: Glands- Sebaceous (Oil)Holocrine (death of secretory cells)Oily secretionPrevents drying and may inhibit bacteriaMost empty into hair follicleExceptions: lips, meibomian glands of eyelids, genitalia5-*

5-*Accessory Skin Structures: Glands- Sudoriferous (Sweat)

Two types traditionally called apocrine and merocrine, but apocrine may secrete in a merocrine or holocrine fashion.

Merocrine or eccrine. Most common. Simple coiled tubular glands. Open directly onto surface of skin. Have own pores. Coiled part in dermis, duct exiting through epidermis. Produce isotonic fluid (water and NaCl, but also excretory because sweat includes ammonia, urea, uric acid and lactic acid). As fluid moves through duct, NaCl is moved by active transport back into the body. Final product is hyposmotic (hypertonic). Sweat.

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- Numerous in palms and soles. Absent from margin of lips, labia minora, tips of penis, and clitoris.Apocrine. Active at puberty. Compound coiled tubular, usually open into hair follicles superficial to opening of sebaceous gland. Secretion: organic compounds that are odorless but, when acted upon by bacteria, may become odiferous.Found in axillae, genitalia (external labia, scrotum), around anus.

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5-*Accessory Skin Structures: Glands- Ceruminous and MammaryCeruminous glands: modified merocrine sweat glands, external auditory meatus.Earwax (cerumen). Composed of a combination of sebum and secretion from ceruminous.Function- In combination with hairs, prevent dirt and insects from entry. Also keep eardrum supple. Mammary glands: modified apocrine sweat glands. Covered with reproductive chapter.

Accessory Skin Structures: Nails AnatomyNail body: stratum corneumEponychium or cuticle is corneum superficial to nail body, hyponychium is corneum beneath the free edgeMatrix and nail bed: cells that give rise to the nail Nail root: extends GrowthGrow continuously unlike hairFingernails grow 0.5-1.2 mm/day; faster than toenails5-*

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5-*Skin Functions: Protection Against abrasion, sloughing off of bacteria as desquamation occurs.Against microorganisms and other foreign substances. Glandular secretions bacteriostatic and skin contains cells of the immune system.Melanin against UV radiation.

Hair on head is insulator and protection against light, and from abrasion. Eyebrows keep sweat out of the eyes; eyelashes protect eyes from foreign objects. Hair in nose and ear against dust, bugs, etc.Nails protect ends of digits, self defense.Acts as barrier to diffusion of water.

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5-*Skin Functions: Sensation and Temperature RegulationSensation: Pressure, temperature, pain, heat, cold, touch, movement of hairs.Temperature Regulation: sweating and radiation. Sweat causes evaporative cooling. Arterioles in dermis change diameter as temperature changes. More or less blood flows through the dermis.

How vitamin D is formedVitamin D3 is made in the skin when 7-dehydrocholesterol reacts with Ultraviolet B (UVB) and is converted to cholecalciferol.It is then carried to the liver where it is converted to 25-hydroxycholecalciferol or Calcidiol.From the liver, it is transported to the proximal tubules of the kidneys and again hydroxylated to form 1,25 dihydroxycholecalciferol or Calcitriol (physiologically active Vit. D)Calcitriol binds to the vitamin D receptors (VDP) of cells found in the heart, gonads, brain, breasts and prostate.VDR activation in the intestine, bone, kidney, and parathyroid gland cells leads to the maintenance of calcium and phosphorus levels in the blood (with the assistance of parathyroid hormone and calcitonin) and to the maintenance of bone content.

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5-*Skin Functions: Vitamin D ProductionBegins here in skin; aids in Ca+2 absorption. Vitamin D (calcitriol): hormone. Stimulates uptake of Ca and PO4 from intestines = (Absorption).Promotes Ca and PO4 release from bonesReduces Ca loss from kidneys = (Resorption).Increases blood Ca and PO4 levels. Functions of Cabone formation, growth, repairclottingnerve and muscle function.

People in cold climates and those who cover the body can be deficient, but calcitriol can be absorbed through intestinal wall. Sources: dairy, liver, egg yolks, supplements.Parathyroid hormone (PTH) - It acts to increase the concentration of calcium (Ca2+) in the blood.whereas Calcitonin (a hormone produced by the parafollicular cells (C cells) of the thyroid gland) acts to decrease calcium concentration.

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5-*Skin Functions: ExcretionRemoval of waste products from the body. Sweat. Water, salt, urea, ammonia, uric acid. Insignificant when compared with kidneys.

5-*BurnsClassificationsFirst-degreeSecond-degreeThird-degreeSkin GraftsSplit skinArtificial skinCadavers or pigs

5-*The Rule of NinesUsed to estimate amount of body that is burned. Note differing proportions in adult and child.

The rule of nines assesses the percentage of burn and is used to help guide treatment decisions including fluid resuscitation and becomes part of the guidelines to determine transfer to a burn unit.You can estimate the body surface area on an adult that has been burned by using multiples of 9.An adult who has been burned, the percent of the body involved can be calculated in the next plate:

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Head = 9%Chest (front) = 9%Abdomen (front) = 9%Upper/mid/low back and buttocks = 18%Each arm = 9% (front = 4.5%, back = 4.5%)Groin = 1%Each leg = 18% total (front = 9%, back = 9%)As an example, if both legs (18% x 2 = 36%), the groin (1%) and the front chest and abdomen were burned, this would involve 55% of the body

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Common disorders of the Integumentary systemAcneAlopecia or baldnessAtopic dermatitisCarbunclesContact dermatitisFuruncles or boilsHyperhydrosis8. Hypertrichosis9. Miliaria or prickly heat10. Psoriasis11. Pediculosis12. Scabies13. Seborrheic dematitis14. Warts

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5-*Aging Effects

Skin more easily damaged because epidermis thins and amount of collagen decreasesSkin infections more likelyWrinkling occurs due to decrease in elastic fibersSkin becomes drier Decrease in blood supply causes poor ability to regulate body temperatureFunctioning melanocytes decrease or increase; age spotsSunlight ages skin more rapidly

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