SKIN AND BODY MEMBRANES BODY MEMBRANES What is

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” Living layer 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” Dead layer cells

5 LAYERS OF THE EPIDERMIS (CLGSB) Stratum corneum Outermost Shingle layer like – rough Dead cells filled with keratin Repels Can water 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