S KIN AND BODY MEMBRANES

B ODY M EMBRANES What is the function of the plasma membrane of a cell?

B ODY M EMBRANES Function of body membranes Cover body surfaces Line body cavities Form protective sheets around organs

C UTANEOUS M EMBRANE Cutaneous membrane = skin Dry membrane Outermost protective boundary

C UTANEOUS M EMBRANE

M UCOUS M EMBRANE Surface epithelium varies Lines all body cavities that open to the exterior body surface Often adapted for absorption or secretion Mouth, esophagus

M UCOUS M EMBRANE

S EROUS M EMBRANES 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

S EROUS M EMBRANES

Specific serous membranes Pleura Around the lungs Pericardium Around the heart

C ONNECTIVE T ISSUE M EMBRANE Synovial membrane Connective tissue only Lines capsules surrounding joints Secretes a lubricating fluid

C ONNECTIVE T ISSUE M EMBRANE

T HE I NTEGUMENTARY S YSTEM The skin and the associated organs of sweat and oil glands, hairs, and nails make up the Integumentary system

T HE SKIN Fun Facts: Avg. makes up about 9-11 lbs. or 7% of your weight Regenerates every days

F UNCTIONS OF THE SKIN Take a rubber glove, cup of water (add some pepper), and a toothpick

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 Often keratinized (hardened by keratin) Dermis Dense connective tissue

S KIN S TRUCTURE Hypodermis is deep to dermis Not part of the skin Anchors skin to underlying organs Composed mostly of 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 “Base” Next to dermis Cells undergoing mitosis New cells are pushed upward Melanin protects new cells from UV light

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum spinosum “Spiny” layer Living cells Protein synthesis-keretin

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum granulosum “Granular” layer Thin Cells dying and begin moving up

5 L AYERS OF THE E PIDERMIS (CLGSB) Stratum lucidum Occurs only in thick, hairless skin of the palms of hands and soles of feet “Clear” layer Dead cells

5 L AYERS OF THE E PIDERMIS (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

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