chapter 45. 4. integumentary system hair skin nails

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Integumentary System

Integumentary SystemChapter 45. 4

Integumentary SystemHairSkinNails

FunctionsCovers your bodyRetains body fluidsProtects against diseasesProtects from injuriesEliminates waste productsRegulates body temperatureProduces Vitamin D

SkinHuman bodys largest organSkin is capable of repairing itself through a lot of wear and tear throughout a lifetimeMade up of layersEpidermisDermisSubcutaneous

EpidermisOuter layer of the skinComposed of many sheets of flattened, scaly epithelial cellsTOP layer (corneal)of epidermis is mostly DEAD cellsUNDERNEATH the top layer (basal) are living cells that are rapidly dividing Epidermis contdCells of the epidermis contain KERATINProtein that gives the skin its rough, leathery texture AND waterproof qualityCells also have MELANINBrown pigment that gives skin its colorMelanocytes are the melanin-producing cellsAbsorbs harmful UV radiationDarker skin is due to more melanin being producedHeredity and tanningLight skinned people need to be careful with UV radiationCan cause mutations in DNA, which lead to SKIN CANCER

DermisInner, thicker layer of the skinComposed of living cells and specialized structuresSensory neuronsBlood vesselsHair folliclesGlandsNail

Sensory Neurons Allow you to sense conditions and signals from your environmentTemperaturePressurePain

Blood VesselsAllow blood to flow to your dermis, providing nourishment to your living cells

Hair Follicles Average adult has 5 million hairs on their bodyProtects and insulates the bodyHair follicle is the cavity deep in the dermis where the hair grows out fromTiny muscles are attached to your hair folliclesGoosebumpsHair is actually composed of dead, keratin-filled cells that overlap each other like shingles on a roofHair color is due to melaninHeredity

GlandsExocrine Glands-glands that release secretions through ducts2 Main exocrine glands of the skin are OIL and SWEAT glands

Oil GlandsOil glandsPrevent hair from drying outProduce SEBUM-fatty substanceCoats the surface to prevent water loss Softens skin and hairCan be toxic to some bacteriaProduction controlled by hormonesAdolescence and increased hormones result in higher activity of oil glandsDead skin, bacteria and sebum cause ACNE

Sweat GlandsReleases excess water, salts, and urea Helps regulate body temperatureSweat is produced when body becomes hotAs sweat evaporates, the body cools

Fat and PoresFat is used to insulate bodyPores allow fluids to leave the bodySweat, OilOil or sweating clogging a pore can cause blackheads or pimples

NailsProtect the end of fingers and toes Composed mainly of keratinNails grow about 1mm per weekGrowth begins at nail rootNails rest on a nail bed which is composed of blood vessels, giving your nails their pink tint

Skin Diagram

Muscle and Integumentary Vocab Quiz Tomorrow (Friday)!!!

Chapter 45 Quiz Monday!!!