unit 3- integummentary system

skin

-largest & heaviest organ

-covered in hair

-vital in maintaining homeostasis

-a protective barrier

skins role in maintaining homeostasis

-maintains proper body temp

-healing wounds,

-production of vitamin D

regulation of body temp (hot)

• nerve impulses signals the body to release heat

• blood vessels dialate

• eccrine sweat glands become active

regulation of body temp (cold)

-muscles in dermal wall contract

• decreases blood flow & heat loss

• sweat glands inactive

• skeletal muscles contract involuntarily

• release heat

• shivering

vitamin D production

-dehyrdocholesterol made by cells in digestive system

• reaches skin and changes to vitamin D when exposed to UV light

4 signs of inflamation

redness, warmth, swelling, pain/pressure

inflammation

wound and surrounding areas become swelled

redness

caused by increased blood flow due to vasodilation

heat

increased metabolism; WBC's try to destroy invaders

swelling

fluid in area due to change in osmotic pressure

edema

abnormal build up of fluid (during swelling)

pain

pressure on nerve endings from fluid

shallow wounds (healing)

epithelial cells divide and fill in gap

deep wounds (healing)

• blood vessels broken

• clot forms and dries into scab

• fibroblasts lay down collagen fibers = scar

-phagocytes remove foreign particles

epidermis

outer (top) layer of skin

(.5mm on eyelids, up to 1.5mm on palms/soles)

dermis

middle layer of skin

-mostly made of dense connective tissue

(.3mm on eyelids, up to 3 mm on upper back)

subcutaneous

bottom layer of skin

aka hypodermis

• loose connective and adipose tissue

• insulation

• major blood supply

epidermis tissue type

stratified squamous epithelium

keritinization

cytoplasm hardens, fills with waxy Keratin

-kills cells to make a tough, waterproof barrier

epidermal layers

stratum corneum

stratum lucidum (only in thick)

stratum granulosum

stratum spinosum

stratum basale

statum basale

contains melanocytes

melanocytes

produces melanin

melanin

dark pigment granules that absorbs UV radiation

of melanocytes

everyone has same amount

skin color depends on ____________ of melanin produced

amount

albinism

body is unable to produce or distribute melanin due to possible genetic defects

• absense on melanocytes

psoriasis

excessive growth and reproduction of kerationocytes followed by inflammation

• caused by immune system mistakenly reacting

-speeds up creation of new cells and slows loss

dermal papillae

project upwards into epidermis

• produce fingerprints

bedsores

interference with blood flow to the dermis can kill epidermal cells

cause of bedsores

lying in one position too long causes weight of body to block skins blood supply

treatment of bedsores

-shifting the patient frequently

-keeping wound clean

subcutaneous injection

into epidermis & dermis layer of skin

-flu shots, penicillin

intradermal injection

into epidermis layer

• tuberculosis (TB) test

intramuscular injection

invades deep tissue (epidermis, dermis, hypodermis)

• epinephrine injection

nails

protective coverings

-cells die and become keratinized forming nail body

(nail body, lunula, cuticle, nail root)

nail root and lunula

contain actively dividing cells

hair follicles

hair development

• specialized epidermal tissue (nourished by dermal blood supply)

• cells divide near base and become keratinized

hair color is determined by _______ near root

melanocytes (more melanin produced = darker hair)

arrector pili

smooth muscles that control "goosebumps"

sebaceous gland

specialized epithelial gland that produces sebum

sebum

an oily mixture that keeps hair and skin soft

-pliable and waterproof

-attached to follicles

sudoriferous (sweat) glands

tiny tube that is attached to a coil in dermis

-eccrine glands respond

eccrine glands

respond to temperature

-sweat comes out of pores

• forehead, back, neck

apocrine glands

respond to emotions

-active @ puberty

-groin, axillary regions

skin receptors respond to ________

heat, pressure, pain, cold

merkel's discs

sense to vibration and movement

-found in stratum basale

root hair plexus

sensitive to hair movement

meissner's corpsucles

light touch (objects that brush along skin)

• dermis

pacinian corpuscles

heavy pressure

-dermis/subcutaneous layer

thermoreceptors

krause corpuscles & ruffini corpuscles