SKIN AND BODY MEMBRANES

BODY MEMBRANES

What is the function of the plasma membrane of a cell?

BODY MEMBRANES

Function of body membranes

Cover body surfaces Line body cavities Form protective sheets around organs

CUTANEOUS MEMBRANE

Cutaneous membrane = skin Dry membrane Outermost protective boundary

CUTANEOUS MEMBRANE

MUCOUS MEMBRANE

Surface epithelium varies

Lines all body cavities that open to the exterior

body surface

Often adapted for absorption or secretion

Mouth, esophagus

MUCOUS MEMBRANE

SEROUS MEMBRANES

Lines open body cavities that are closed to the exterior of the body

Occur in pairs separated by serous fluid

Visceral layer: outside of the organ Parietal layer: portion of the wall of ventral body

cavity

SEROUS MEMBRANES

SEROUS MEMBRANES

Specific serous membranes

Pleura Around the lungs

Pericardium Around the heart

CONNECTIVE TISSUE MEMBRANE

Synovial membrane

Connective tissue only Lines capsules surrounding joints Secretes a lubricating fluid

CONNECTIVE TISSUE MEMBRANE

THE INTEGUMENTARY SYSTEM

The skin and the associated organs of sweat and oil glands, hairs, and nails make up the Integumentary system

THE SKIN

Fun Facts:

Avg. makes up about 9-11 lbs. or 7% of your weight Regenerates every 25-45 days

FUNCTIONS OF THE SKIN Take a rubber glove, cup of water (add some

pepper), and a toothpick

SKIN STRUCTURE (EDH)

epidermis (epithelial) dermis (fibrous) hypodermis (subcutaneous – fat)

SKIN STRUCTURE (EDH)

SKIN STRUCTURE

Epidermis—outer layer Stratified squamous epithelium Often keratinized (hardened by keratin)

Dermis Dense connective tissue

SKIN STRUCTURE

Hypodermis is deep to dermis

Not part of the skin Anchors skin to underlying organs Composed mostly of 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

“Base”

Next to dermis

Cells undergoing mitosis

New cells are pushed upward

Melanin protects new cells from UV light

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum spinosum

“Spiny” layer

Living cells

Protein synthesis-keretin

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum granulosum

“Granular” layer

Thin

Cells dying and begin moving up

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum lucidum

Occurs only in thick, hairless skin of the palms of hands and soles of feet

“Clear” layer

Dead cells

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum corneum

Outermost layer

Shingle like – rough

Dead cells filled with keratin

Repels water

Can become thick from irritation (callus)

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