Integumentary SystemIntegumentary System

Integumentary systemIntegumentary system

• A barrier against infection and A barrier against infection and injury, helps regulate body injury, helps regulate body temperature, removes wastes, temperature, removes wastes, provides protection against UV provides protection against UV radiation from the sunradiation from the sun

• Includes skin, hair, nails, variety of Includes skin, hair, nails, variety of glandsglands

Skin Skin

• Two main layersTwo main layers– Epidermis- the outer layerEpidermis- the outer layer– Dermis –inner layerDermis –inner layer– Hypodermis –subcutaneous and is made Hypodermis –subcutaneous and is made

mostly of fat and loose connective mostly of fat and loose connective tissue for insulationtissue for insulation

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The Skin

Epidermis Epidermis

• Outside layer comes in contact with Outside layer comes in contact with the environment; made of dead cellsthe environment; made of dead cells

• Inside layer has live cells that Inside layer has live cells that undergo rapid cell division to push undergo rapid cell division to push older cells to the outer layerolder cells to the outer layer

• Older cells become flattened and Older cells become flattened and make keratin (tough fiber) which make keratin (tough fiber) which gives the outer layer a tough, gives the outer layer a tough, flexible, water-proof propertyflexible, water-proof property

Epidermis Epidermis

• Outer layer of cells is shed once Outer layer of cells is shed once every four to five weeksevery four to five weeks

• Epidermis also has melanin Epidermis also has melanin (pigment) that protects skin from (pigment) that protects skin from damage from UV raysdamage from UV rays

• Differences in skin color comes from Differences in skin color comes from different amounts of melanindifferent amounts of melanin

• No blood vessels in epidermisNo blood vessels in epidermis

Dermis Dermis

• Beneath epidermis and contains Beneath epidermis and contains collagen, blood vessels, nerve collagen, blood vessels, nerve endings, glands, sensory receptors, endings, glands, sensory receptors, smooth muscles, and hair folliclessmooth muscles, and hair follicles

• Helps maintain homeostasis by Helps maintain homeostasis by controlling body temperaturecontrolling body temperature

• 2 types of glands2 types of glands– Sweat glandsSweat glands– Subaceous (oil) glandsSubaceous (oil) glands

Sweat glandsSweat glands

• Produce perspiration or sweat which Produce perspiration or sweat which contains salts, urea, and other contains salts, urea, and other compoundscompounds

• As it evaporates it lowers body As it evaporates it lowers body temperaturetemperature

• Since it also gets rid of wastes from Since it also gets rid of wastes from the blood (urea) it is the blood (urea) it is also an organ also an organ of excretionof excretion

Subaceous glandsSubaceous glands

• Secrete oily substance called sebumSecrete oily substance called sebum• Spreads out on surface of skin to Spreads out on surface of skin to

keep the keratin-rich epidermis keep the keratin-rich epidermis flexible and waterproofflexible and waterproof

Hair Hair

• Hair covers almost every exposed area of Hair covers almost every exposed area of the bodythe body

• Head hair provides protection from UV Head hair provides protection from UV radiation and insulates from the coldradiation and insulates from the cold

• Hair in nostrils, ear canals, and around Hair in nostrils, ear canals, and around eyes (eyelashes) prevent dirt and particles eyes (eyelashes) prevent dirt and particles from entering the bodyfrom entering the body

• Produced in hair follicles of dermis; in Produced in hair follicles of dermis; in close association with subaceous glands close association with subaceous glands to keep hairs in good conditionto keep hairs in good condition

Nails Nails

• Grow from nail root on fingers and Grow from nail root on fingers and toestoes

• Cells fill with keratin to make a Cells fill with keratin to make a tough, plate like nail to protect tips tough, plate like nail to protect tips of fingers and toesof fingers and toes