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!!!
