S KIN AND BODY MEMBRANES

T HE SKIN Fun Facts: Avg. makes up about 9-11 lbs. or 7% of your weight Regenerates every days Every minute you lose 30,000-40,000 dead skin cells

S KIN S TRUCTURE (EDH) Epidermis (epithelial) Dermis (fibrous) Hypodermis (subcutaneous – fat)

S KIN S TRUCTURE (EDH)

S KIN S TRUCTURE Epidermis—outer layer Stratified squamous epithelium

S KIN S TRUCTURE Dermis Dense connective tissue Not part of the skin Anchors skin to underlying organs Mostly adipose tissue (subcutaneous tissue)

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum corneum Statum lucidum Stratum granulosum Stratum spinosum Statum basale

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum basale

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum spinosum

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum granulosum

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum lucidum

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum corneum

NOTE: Thick skin- covers palms, fingertips, soles of feet Thin skin – covers rest of body missing stratum lucidum and sometimes stratum granulosum

M ELANIN Pigment produced by melanocytes Amount of melanin produced depends upon genetics and exposure to sunlight

M ELANIN – S KIN C OLOR GENETICS is the key factor Quantity of melanin (yellow to reddish- brown to black) protects skin from UV radiation Melanocytes use enzyme tyrosinase to convert tyrosine into dark brown melanin pigment, albinos lack DNA code to make tyrosinase

A LBINISM IN H UMANS

M ELANIN – S KIN C OLOR Sunlight increases melanin production by the release of hormones freckles or moles are accumulations of melanin other pigments such as carotene or hemoglobin contribute to skin color

M ELANIN – S KIN C OLOR Prolonged exposure causes substantial melanin buildup which helps protect the DNA of viable skin cells from UV radiation by absorbing the light and dissipating the energy as heat

D ERMIS Two layers Papillary layer (upper dermal region) Reticular layer (deepest skin layer)

D ERMIS Papillary layer (upper dermal region)

D ERMIS Reticular layer (deepest skin layer)

D ERMIS O VERVIEW Collagen fibers give skin its toughness Elastic fibers give skin elasticity Blood vessels play a role in body temperature regulation

S KIN A PPENDAGES Glands Hair Hair follicles Nails

S EBACEOUS GLANDS Produce oil Glands are activated at puberty

S EBACEOUS GLANDS

S WEAT GLANDS Produce sweat Widely distributed in skin Two types Eccrine Apocrine

S WEAT GLANDS

H AIR Produced by hair follicle Consists of hard keratinized epithelial cells Melanocytes provide pigment for hair color

H AIR Hair follicle- shaft, follicle (root) Growth- 4 in./year or 2 mm/week

H AIR Associated hair structures Hair follicle Arrector pili muscle Sebaceous gland Sweat gland

N AILS Scale-like modifications of the epidermis

N AILS Consists of: free edge Body Root Cuticle Lunula Growth- 0.5 mm/week

N AILS

Did you know that your fingernails grow much faster than your toe nails? 3-4 times faster!

S KIN I NFECTIONS AND A LLERGIES Contact dermatitis Exposures cause allergic reaction Cold sores Caused by virus Impetigo Caused by bacterial infection Psoriasis Cause is unknown Triggered by trauma, infection, stress

S KIN I NFECTIONS AND A LLERGIES

B URNS Burns Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals

B URNS Associated dangers

R ULE OF N INES Way to determine the extent of burns Body is divided into 11 areas for quick estimation Each area represents about 9% of total body surface area

R ULE OF N INES

S EVERITY OF B URNS First-degree burns Second-degree burns Third-degree burns

S EVERITY OF B URNS

C RITICAL B URNS Burns are considered critical if Over 25% of body has second-degree burns Over 10% of the body has third-degree burns There are third-degree burns of the face, hands, or feet