Integumentary

Largest organ of body

Composed of

• Sweat glands
• Oil glands
• nails
• hair
• skin

Specialized tissue

• glands secrete fluids
• nerves carry impulses
• blood vessels assist in temperature regulation

The skin

The Skin is a Protector

• a barrier against microorganisms
• protects organs from injury
• maintains & regulates body temperature
• receptor for sensations (hot, cold, touch, pain)
• guards deeper tissue against water loss, salts & heat
• removes wastes

3 layers of skin

• Epidermis
• Dermis
• Subcutaneous

Epidermis

• outer most layer
• cellular layer
• composed of epithelium
• no blood vessels, lymph vessels, CT, cartilage or fat

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• depends on deeper dermis & capillary network for nourishment
• deepest layer is the basal layer
• constantly renewing itself
• Melanocytes: black pigment

Dermis

• second layer of skin below the epidermis
• composed of blood, lymph vessels, & nerve fibers
• contains hair follicles, sweat glands, & oil glands
• contains CT cells 7 fibers
• fibers are collagen (glue)
• hair shafts: muscle is the arrector pilli

Subcutaneous layer

• made of CT that specializes in fat
• lipocytes: store fat
• protects deeper tissues
• heat insulator
• connects dermis to muscles & organs below
• fat is an insulator

Sebaceous glands

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• produce oily secretion called sebum
• excreted through pores
• lubricates skin
• ducts open to hair follicles
• influenced by sex hormones

Sudoriferous glands

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• coiled glands found on almost all body surfaces
• helps cool body
• secrteted through pores
• pure water, dissolved salts makeup less than 1%
• colorless 7 odorless
• odor is due to bacteria

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• mainly active at puberty
• ceruminous glands:ear wax
• diaphoresis: carrying through persperation

Hair

• composed of horny cells
• cells hold the hair follicle
• melanocytes: supply pigment for hair color
• hair color depends on amount of melanin present
• homone production decreses with age hair loses color and becomes transparent (gray)

Nails

• hard keratin plates
• composed of horny cells
• grow in thickness and length by division of cells at the base of the nail
• grow 1mm a week
• may regrow completely in 3-5 months
• toenails grow more slowly than finger nails