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Integumentary System Membrane Classification • Epithelial membranes – cutaneous – mucous – serous • Connective tissue membranes – synovial Cutaneous Membrane - skin Functions? • • • • • • Protection Excretion Maintenance of body temperature Synthesis Storage Detection of sensation Thick vs. Thin Skin Structure • Epidermis – outer layer – Stratified squamous epithelium – Often keratinized (hardened by keratin) • Dermis – Dense connective tissue Epidermal strata Epidermal strata • Stratum basale (germinativum) – cells dividing – next to dermis – melanocytes - umbrella for DNA Epidermal strata • Stratum spinosum – spiny layer • Stratum granulosum – grainy layer – still living – produce keratin • Stratum lucidum – thick skin – dead Epidermal strata • Stratum corneum – keratinized “shinglelike” cells – water resistant – 20-30 cell layers thick – 25-45 days What happens to the epidermis when… • You have a blister? • You take a bath? What factors contribute to skin color? • Carotene • Blood flow/hemoglobin • Melanin Dermis consists of connective tissue Dermis has 2 layers – Papillary layer • Projections called dermal papillae • Pain receptors • Capillary loops – Reticular layer • Blood vessels • Glands • Nerve receptors Dermal papillae Hypodermis • Consists of areolar and adipose tissue • Not really part of the integumentary system • Target site for subcutaneous injection Glands in the skin • Sebaceous glands – Produce oil (sebum) • Lubricant for skin/hair • Kills bacteria – Most with ducts that empty into hair follicles – Glands are activated at puberty Sweat (sudoriferous) glands • Apocrine sweat glands – Armpits – Produce a stick, cloudy, and odorous secretion – Begin secreting at puberty Eccrine sweat glands • Eccrine – Found all over body – Open via duct to pore on skin surface – Not odorous, inhibit bacterial growth eccrine eccrine eccrine Sweat • Composition – Mostly water – Some metabolic waste – Fatty acids and proteins (apocrine only) • Function – Helps dissipate excess heat – Excretes waste products – Acidic nature inhibits bacteria growth • Odor is from associated bacteria Hair • produced by hair bulb • hard keratinized cells • color produced by melanocytes Hair Hair • arrector pili-muscle • shape determines texture – oval: wavy – flat: curly – round: straight Integumentary Repair Burns • Tissue damage and cell death – heat – electricity – UV radiation – chemicals • Associated dangers – dehydration – electrolyte imbalance – circulatory shock Burns • First-degree burns – Only epidermis is damaged – Skin is red and swollen • Second degree burns – Epidermis and upper dermis are damaged – Skin is red with blisters • Third-degree burns – Destroys entire skin layer – Burn is gray-white or black