Integumentary System: Anatomy, Functions, and Skin Components, Quizzes of Physiology

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Functions of Integumentary system

-Protects against water (keratin), prevents water loss, microorganisms (oil glands), UV light damage (melanin)- Homeostasis: "same state" (ex. body fluids, temperature)- Others: cutaneous absorption (ex. lipids can cross easily-so many toxins and pesticides can cross); synthesis of vitamin D, which causes maintenance of calcium)-sensory receptors TERM 2

Epidermis

DEFINITION 2 -outer layer (protective, thin)-constantly replenished (bottom comes up, dead skin falls off: 6-8 weeks)-stratified squamous epithelium (.007-.12mm)-cells in bottom layer that are alive secrete keratin (toughens/waterproofs skin)- ^keratin=callouses-5 layers in thick skin, 4 in thin TERM 3

Epidermal Layers

DEFINITION 3 -stratum BASAL:-stratum SPINOSUM:-stratum GRANULOSUM: 1-5 layers flattened keratinocytes, keratohyaline granules (form keratin), lamellated granules (waterproof), prevents diffusion of materials to higher layers - stratum LUCIDUM: "transition zone"; thick skin only (palms, soles) -stratum CORNEUM: TERM 4

Dermis

DEFINITION 4 -thickest layer, all living cells-contains connective tissue- nerves, hair follicles-elastin fibers (stretchiness decreases w/age), collagen and reticular fibers-2 LAYERS:papillary: superficial, 20% areolar CT, fingerlike projectionsreticular: 80%, dense irregular CT, network of collagen-temp reg- TERM 5

Hypodermis

DEFINITION 5 -binding the skin to underlying layers. insulates and cushions so it's NOT really part of the skin-loose (areolar) CT, some collagen and elastin-vascular (large blood vessels, feed to capillaries in dermis)-subcutaneous adipose tissue (females have a thicker hypodermis than males -8%) function of adipose is to insulate

Skin Pigments

-Melanin: melan=melancholy-dark-black bile; made from amino acid tyrosine. albinos lack enzyme tyrosine. color range: yellow- reddish brown-black. found in epidermis. function: protect against UV radiation-Carotene: yellow-orange pigment; lipid substance made from cholesterol, found in strata corneum and fatty tissue of hypodermis-Hemoglobin: found in RBCs; pink and blue tones to skin, protein with iron, picks up O TERM 7

Skin Appendages

DEFINITION 7 -derive from epidermis and extend to dermis-Hair: primary function to sense touching of skin; flexible strands made of dead, keratinized cells (keratin is hard) (3 layers: medulla, cortex, cuticle)-made up of shaft and root-hair pigment is made by melanocytes in hair follicle and transferred into root, produces colors-black, brown, red, blonde-white/gray hair= decreased melanin production TERM 8

Hair Follicles

DEFINITION 8 -extend from epidermis into dermis-deep end forms hair bulb-nerve endings sense touch-hair papilla: portion of dermis with knot of capillaries that nourish, stimulate growth- hair matrix: epithelial cells in hair bulb-each follicle has a bundle of smooth muscle cells (arrector pili)-cause hair to stand on end TERM 9

Hair Facts

DEFINITION 9 -vellus or terminalvellus=body hair (peach fuzz)terminal-hair on scalphair grows about 2mm/week-each follicle undergoes different growth cycles (active phase: new hair pushes old out)-with age, hair thins when not replaced quickly=diff. baldness TERM 10

Glands

DEFINITION 10 -originate in epidermis BUT are located in the dermis-exocrine (have ducts, secretions used locally)-two main kinds: SUBaceous and SUDoriferous-special kinds=ceruminous 9ear wax), mammary- sebaceous (latin sebum-grease) : occurs all over body except palms, soles; simple alveolar, secrete oil onto hair shaft. Oil (sebum) is waterproof (made of lipids)-keep hair from becoming brittle and skin from cracking-sex hormones regulate these glands-causes teenage acne problem

Sudoriferous

latin sudor=sweat (blood filtrate; 99% H2O; salt)-excrete sweat onto skin surface: most numerous on palms, soles, axillary (pits) and pubic regions, forehead-2 kinds:Eccrine-aka merocrine; more numerous. function=evaporative cooling. location=all over body. simple tubular gland, coiled, releases sweat through pores- Apocrine (larger)=axillary, pubic regions. special sweat that also contains fat and proteins...... TERM 12

Nails

DEFINITION 12 -scale-like modification of epidermis made of hard keratin- free edge, body, root, nail bed-pink appearance due to capillary network of dermis underneath-nail matrix: actively growing part TERM 13

Disorders of the Integumentary System

DEFINITION 13 -BURNS: first degree=epidermissecond=epidermis and upper dermisthird=entire thickness of skin damagedSKIN CANCER: basal cell carcinoma: least malignant and most common, arises in stratum basalsquamous cell carcinoma: arises from stratum spinosummelanoma: most dangerous, melanocytes