SKIN AND BODY MEMBRANES

THE SKIN

Fun Facts:

Avg. makes up about 9-11 lbs. or 7% of your weight

Regenerates every 25-45 days

Every minute you lose 30,000-40,000 dead skin cells

SKIN STRUCTURE (EDH)

Epidermis (epithelial) Dermis (fibrous)Hypodermis (subcutaneous – fat)

SKIN STRUCTURE (EDH)

SKIN STRUCTURE

Epidermis—outer layer Stratified squamous epithelium

SKIN STRUCTURE

Dermis Dense connective tissue

Not part of the skin Anchors skin to underlying organs Mostly adipose tissue (subcutaneous tissue)

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum corneum

Statum lucidum

Stratum granulosum

Stratum spinosum

Statum basale

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum basale

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum spinosum

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum granulosum

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum lucidum

5 LAYERS OF THE EPIDERMIS (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

MELANIN

Pigment produced by melanocytes

Amount of melanin produced depends upon genetics and exposure to sunlight

MELANIN – SKIN COLOR

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

ALBINISM IN HUMANS

MELANIN – SKIN COLOR 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

MELANIN – SKIN COLOR

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

DERMIS

Two layers

Papillary layer (upper dermal region)

Reticular layer (deepest skin layer)

DERMIS Papillary layer (upper

dermal region)

DERMIS

Reticular layer (deepest skin layer)

DERMIS OVERVIEW

Collagen fibers give skin its toughness

Elastic fibers give skin elasticity

Blood vessels play a role in body temperature regulation

SKIN APPENDAGES

Glands Hair Hair follicles Nails

SEBACEOUS GLANDS Produce oil

Glands are activated at puberty

SEBACEOUS GLANDS

SWEAT GLANDS

Produce sweat

Widely distributed in skin

Two types Eccrine Apocrine

SWEAT GLANDS

HAIR

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

HAIR

Hair follicle- shaft, follicle (root)

Growth- 4 in./year or 2 mm/week

HAIR

Associated hair structures

Hair follicle

Arrector pili muscle

Sebaceous gland

Sweat gland

NAILS

Scale-like modifications of the epidermis

NAILS

Consists of:free edgeBodyRootCuticleLunula

Growth- 0.5 mm/week

NAILS

NAILS

Did you know that your fingernails grow much faster than your toe nails?

3-4 times faster!

SKIN INFECTIONS AND ALLERGIES

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

SKIN INFECTIONS AND ALLERGIES

BURNS

Burns Tissue damage and cell death caused by heat,

electricity, UV radiation, or chemicals

BURNS

Associated dangers

RULE OF NINES

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

RULE OF NINES

SEVERITY OF BURNS

First-degree burns

Second-degree burns

Third-degree burns

SEVERITY OF BURNS

CRITICAL BURNS

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