Integumentary System

Integumentary system A barrier against infection and injury, helps regulate body temperature, removes wastes, provides protection against UV radiation from the sunA barrier against infection and injury, helps regulate body temperature, removes wastes, provides protection against UV radiation from the sun Includes skin, hair, nails, variety of glandsIncludes skin, hair, nails, variety of glands

Skin Two main layersTwo main layers –Epidermis- the outer layer –Dermis –inner layer –Hypodermis –subcutaneous and is made mostly of fat and loose connective tissue for insulation

To return to the chapter summary click escape or close this document. The Skin

Epidermis Outside layer comes in contact with the environment; made of dead cellsOutside layer comes in contact with the environment; made of dead cells Inside layer has live cells that undergo rapid cell division to push older cells to the outer layerInside layer has live cells that undergo rapid cell division to push older cells to the outer layer Older cells become flattened and make keratin (tough fiber) which gives the outer layer a tough, flexible, water-proof propertyOlder cells become flattened and make keratin (tough fiber) which gives the outer layer a tough, flexible, water-proof property

Epidermis Outer layer of cells is shed once every four to five weeksOuter layer of cells is shed once every four to five weeks Epidermis also has melanin (pigment) that protects skin from damage from UV raysEpidermis also has melanin (pigment) that protects skin from damage from UV rays Differences in skin color comes from different amounts of melaninDifferences in skin color comes from different amounts of melanin No blood vessels in epidermisNo blood vessels in epidermis

Dermis Beneath epidermis and contains collagen, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair folliclesBeneath epidermis and contains collagen, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair follicles Helps maintain homeostasis by controlling body temperatureHelps maintain homeostasis by controlling body temperature 2 types of glands2 types of glands –Sweat glands –Subaceous (oil) glands

Sweat glands Produce perspiration or sweat which contains salts, urea, and other compoundsProduce perspiration or sweat which contains salts, urea, and other compounds As it evaporates it lowers body temperatureAs it evaporates it lowers body temperature Since it also gets rid of wastes from the blood (urea) it is also an organ of excretionSince it also gets rid of wastes from the blood (urea) it is also an organ of excretion

Subaceous glands Secrete oily substance called sebumSecrete oily substance called sebum Spreads out on surface of skin to keep the keratin-rich epidermis flexible and waterproofSpreads out on surface of skin to keep the keratin-rich epidermis flexible and waterproof

Hair Hair covers almost every exposed area of the bodyHair covers almost every exposed area of the body Head hair provides protection from UV radiation and insulates from the coldHead hair provides protection from UV radiation and insulates from the cold Hair in nostrils, ear canals, and around eyes (eyelashes) prevent dirt and particles from entering the bodyHair in nostrils, ear canals, and around eyes (eyelashes) prevent dirt and particles from entering the body Produced in hair follicles of dermis; in close association with subaceous glands to keep hairs in good conditionProduced in hair follicles of dermis; in close association with subaceous glands to keep hairs in good condition

Nails Grow from nail root on fingers and toesGrow from nail root on fingers and toes Cells fill with keratin to make a tough, plate like nail to protect tips of fingers and toesCells fill with keratin to make a tough, plate like nail to protect tips of fingers and toes