THE INTEGUMENTARY SYSTEM THE SKIN ANATOMY Notes MEMBRANES

THE INTEGUMENTARY SYSTEM “THE SKIN” - ANATOMY Notes

MEMBRANES Sheet-like structures § Cover and protect body surfaces § Secrete fluid for lubrication

EPITHELIAL MEMBRANES Cutaneous – skin Serous – lines body cavity & covers surface of organs § Pleura – thoracic cavity § Peritoneum – abdominal cavity Mucous – line surfaces (openings) § Secrete slimy mucus keeps membranes moist and soft

THE SKIN Did you know? – Draw a 1 inch square on your paper… 1 square inch of skin contains… § 500 sweat glands § 1000 nerve endings § yards of vessels § 100 oil glands § 150 pressure sensors § 75 heat sensors § 10 cold sensors § millions of cells The whole organ makes up 16% of a person’s body weight

LAYERS OF THE SKIN Epidermis (thin, outer layer) – layers of tissue § Superficial layers (keratinized cells – dry, dead) flake off § Deep layers = rapidly dividing cells (move toward surface) § Cytoplasm replaced by keratin – tough, waterproof protein § Deepest layers produce pigments § Melanin (melanocytes) – genetics/sun exposure § Areas with little melanin used to indicate blood flow (nails/lips) § flushed (normal) § blue (decrease blood flow) – cyanosis

EPIDERMIS

LAYERS OF THE SKIN Dermis (deep, thick layer) – cells scattered with fibers § Upper portion forms ridges/grooves – fingerprints § Lower portion contains collagen (strength), elastic fibers, & nerve endings – amount decreases with age

DERMIS

APPENDAGES Hair – protection/warmth § Erector Pili muscles – goose bumps

APPENDAGES Receptors (touch, pain, pressure, temp. ) § Sensation becomes part of our awareness when transmitted to brain where info can be… § Amplified § Reduced § Eliminated

APPENDAGES Nails § Protection (hard, plate-like, keratinized cells)

APPENDAGES Sweat (sudoriferous) Glands § Eccrine gland – watery § Perspiration (eliminate waste, temp. control) § Apocrine gland – thick, milky § Armpit/groin (smell (BO) – bacteria)

APPENDAGES Sebaceous Glands – secrete oil for hair/skin § Sebum – lubrication (prevents drying/cracking)

THE SKIN