integumentary system our 1 st system!. integumentary system includes skin, sweat glands, sebaceous...

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Integumentary System OUR 1 ST SYSTEM!

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  • Integumentary SystemOUR 1ST SYSTEM!

  • Integumentary systemIncludes skin, sweat glands, sebaceous (oil) glands, hair, and nailsSKIN (or cutaneous membrane or integument)Largest organ

    Makes up 16% of total body mass.0.5 (eyelids) to 4 (heels) mm thickMostly 1-2 mmAbout 2 square meters in adultsWeighs about 10-11 lbsFun FactsDont write


  • EpidermisSuperficial layerKeratinized stratified squamous epithelium AvascularCells are continually replacedOld cells keratinize- hardenTHICK SKIN- 5 layers (palms, fingers, soles of feet)THIN SKIN- 4 layers (rest of body)

  • Epidermis cont.90% of cells are keratinocytes: produce keratin a protein - protects skin from heat, microbes, and chemical. Produce lamellar granules release a lipid that decreases water entry and loss8% melanocytes melanin

  • Epidermis Layers (from deep to superficial)1. Stratum Basale (Base layer)- firmly attached to the dermis, cells rapidly divide2. Stratum Spinosum cells start to flatten and appear spiny, produce keratin 3. Stratum Granulosum- cells are flat and start to die 4. Stratum Lucidum present only in thick skin; clear, flat, dead cells5. Stratum Corneum- durable overcoat of dead cells, thickest layer

  • DermisDeep to epidermisDense irregular connective tissue and elastic fibers gives skin toughness and elasticity Rich nerve and blood supplyContains hair follicles, sebaceous glands (oil), and sweat glands.Pain and touch receptorsstretch marks (striae) caused by small tears in the dermis

  • Subcutaneous layer technically not a layer of skinHypodermisareolar and adipose tissueInsulation, protection, and contains major blood vessels.

  • Check for understanding4 - I can explain to my peers characteristics of each of the major layers of the skin 3 - I understand characteristics of each of the major layers of the skin2 - I understand, but need to review my notes.1 - skin has layers???

  • Skin accessory structures

  • HairFunction: protects the bodyScalp: also decreases heat lossEyebrows/eyelashes/nostrils/external ear: protect eyes/nose/ears from foreign particles.Also function in sensing light touch.

  • Hair anatomyMade of column of dead, keratinized cells bonded together by extracellular proteinsShaft: above skinRoot: deep into dermisBulb:base; blood vessels nourish

  • Make-up of shaft and rootMedulla: can be lacking Cortex: Cuticle: made of single layer of thin , flat cells that are keratinized; arranged like shingles

  • Arrector pili: muscle pulls the hair shafts perpendicular to the skinOccurs when emotionally upset or cold

  • Hair growthVisible hair is dead, but portion of its root are aliveGoes through a growth stage and resting stage (scalp hair: 2-6 years, 3 months)Normal hair loss: 70-100 hairs a dayCan by altered by chemotherapy, radiation, age, genetics, gender, emotional stress, rapid weight loss, childbirth.

  • NailsTightly packed, hard, dead, keratinized epidermal cellsConsists of a nail body, free edge and a nail root

  • Most active growing region is the lunula, half moon shaped area at the base of the nail.Nail slides forward over the nail bed.

  • Nail growthDetermined by rate of mitosis of cells deep to nail root.Affected by age, health, nutritionFunction: help grasp small objects, protection for ends of digits, and allow us to scratch various parts of the body.

  • Sebaceous Glands (oil)Epithelial tissueGland lies in dermis and opens into hair follicleNot on palm and soles, varied sizes elsewhereSecrete sebum (fatty material, protein, and salt).Coats hair prevents dryingPrevents too much evaporation from skin, keeps skin soft and pliable, inhibits growth of certain bacteria.Oversecretion (due to hormones) causes acne due to bacteria

  • Sudoriferous Glands (sweat)Epithelial tissueEach gland is a tiny tube that starts as a coil shaped ballTwo types: Eccrine thermal regulationApocrine cold sweat: stimulated during emotional stress and sexual excitement

  • 1. Eccrine Glands

    Most numerousActive from birth Common on forehead, back, neckOriginates in dermisEmpties into pores on surface of skinSecrete: water, ions, urea, uric acid, ammonia, amino acids, glucose, and lactic acid.Function: regulate body temperature through evaporation.

  • 2. Apocrine Glands

    Found mainly in axillary and inguinal regions.Originates in hypodermisEmpties through a duct into hair follicleSame components of eccrine sweat plus lipids and proteinStimulated during emotional stress and sexual excitementBegin functioning at pubertyCommonly called cold sweat

  • SKIN COLORWhat influences our appearance?

  • Pigments:

  • 1. melaninProduced from melanocytes of epidermisVaries byColor: yellow-brown-blackamountFreckles/molesNatural shield

  • 2. hemoglobinRBCs; carry O2Hidden by melanin

  • 3. caroteneYellow-orange pigmentFrom diet

  • Skin color as a diagnostic clueCyanotic (bluish): Jaundice (yellowish): Erythema (red): Pallor (paleness):

  • Functions of skin

  • 1. Regulation of Body Temp.

    HOTBlood rushes to skin heat releasedSweat- evaporation coolsCOLDBlood moves to vital organsGoose bumps

  • 2. protection1. keratin protects underlying tissues from microbes, abrasion, heat, chemicals2. Lipids: guards against dehydration3. Sebum (oil): prevents skin and hairs from drying and kills surface bacteria4. Acidic pH of sweat inhibits growth of bacteria5. Melanin: shield against UV light.

  • 3. Cutaneous sensationsTactile: touch, pressure, vibration, ThermalPain

  • 4. Excretion and absorptionExcretion: sweat removes water and small amounts of salts, carbon dioxide, ammonia and ureaAbsorption of some lipid-soluble materials: Fat-soluble vitamins (ex. A, D, E,K)Lead, mercuryChemical in poison ivy

  • Medical application of this function:

    transdermal drug administration (a patch):examples: nicotine, hormones to prevent contraception

  • 5. Synthesis of vitamin DUV activates a molecule to turn into vitamin D (a hormone that aids in the absorption of calcium from intestines into the blood)


  • Cause: sunTypes: basal cell carcinoma78% of all, from stratum basale, rarely metastasizeSquamous cell carcinomas20% of all, squamous cells of epidermis, some tendency to metastasizeMalignant melanomas2% of all, from melanocytes, metastasize and kill rapidlyEarly detection: ABCD

  • RISK FACTORSSkin typeSun exposureFamily historyAgeImmunological statusRisk doubled in last 20 years: ozone depletion and more time in sun/tanning beds

  • Wound healingRepairs skin to normal (or near normal) structure and function2 types

  • 1. Epidermal wound healingCenter may penetrate dermis, edges involve only slight damage to superficial epidermal cellsBasal cells divide and migrate across wound until they encounter basal cells from the other side.

  • 2. Deep wound healingInjury to dermis and subcutaneous layer.Phases:Inflammatory phase: formation of blood clot in wound; vasodilation enhances delivery of helpful cellsMigratory phase: scab, epithelial cells migrate beneath to bridge wound, scar tissue starts (collagen fibers), blood vessel regrowth

  • Proliferative phase: much growth of scar tissue, blood vessels, and epithelial cells beneath scabMaturation phase: scab sloughs off

    (scar tissue: more collagen fibers densely packed, less elasticity, fewer blood vessels, may not have same # of hairs, glands or sensory structures as undamaged skin)