Integumentary SystemChapter 45. 4

Integumentary SystemHairSkinNails

Functions1) Covers your body2) Retains body fluids3) Protects against diseases4) Protects from injuries5) Eliminates waste products6) Regulates body temperature7) Produces Vitamin D

SkinHuman body’s largest organSkin is capable of repairing itself through a

lot of wear and tear throughout a lifetimeMade up of layers

EpidermisDermisSubcutaneous

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 cont’dCells of the epidermis contain KERATIN

Protein that gives the skin its rough, leathery texture AND waterproof quality

Cells also have MELANINBrown pigment that gives skin its colorMelanocytes are the melanin-producing

cellsAbsorbs harmful UV radiationDarker skin is due to more melanin

being produced Heredity and “tanning”

Light skinned people need to be careful with UV radiation Can 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 follicles

GoosebumpsHair is actually composed of dead, keratin-filled cells

that overlap each other like shingles on a roofHair color is due to melanin

Heredity

GlandsExocrine Glands-

glands that release secretions through ducts

2 Main exocrine glands of the skin are OIL and SWEAT glands

Oil GlandsOil glands

Prevent hair from drying outProduce SEBUM-fatty substance

Coats the surface to prevent water loss Softens skin and hair Can be toxic to some bacteria Production controlled by hormones

Adolescence and increased hormones result in higher activity of oil glands

Dead skin, bacteria and sebum cause ACNE

Sweat GlandsReleases excess water, salts, and urea Helps regulate body temperature

Sweat 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, Oil

Oil 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!!!