1. T HE I NTEGUMENTARY S YSTEM

2. F UNCTIONS OF S KIN Regulates body temp. Stores blood Protects body from external env’t. Detects cutaneous sensations Excretes and absorbs substances Synthesizes vitamin D

3. S KIN LAYERS : EPIDERMIS Stratified squamous epithelium 90% have Keratin: a tough, fibrous protein (protection) Granules: release a water-repellent sealant 8% have melanin: pigment that absorbs UV light

4. Langerhans cells: immune response, recognize invading microbes Stratum basale: simple cuboidal. Stem cells divide to produce new layers above. Outer layer is 30 layers of flattened, dead cells Light blue - Langerhans cell Dark blue- melanocyte Brown- stem cells

6. L OWER LAYERS Dermis: connective tissue, elastic fibers. Blood vessels Nerve endings Hair follicles Sweat glands Oil glands Subcutaneous: fat, collagen, elastic fibers

7. S KIN C OLOR Combination of melanin, carotene, and hemoglobin pigments. # of melanocytes the same in everyone, but the amount of melanin differs. Tanning: increased melanin production to absorb UV.

8. U SING SKIN COLOR TO DIAGNOSE ILLNESS Yellow skin/eyes- liver disease (jaundice) No melanin - albinism Bluish nails- cyanosis Erythema- inflammation, allergies

9. S KIN CANCER Cause: excessive exposure to the sun. 1million cases per year in US, number increasing. Basal cell: tumors in the stratum basale:78% Squamous cell: 20% Tumors in stratum spinosum of epidermis. Melanoma: arise from melanocytes- life threatening. 1:75 chance lifetime risk. Asymmetry Border Color Diameter

10. B URNS 1 st degree: epidermis only, no blisters 2 nd degree: epidermis + dermis, blisters 3 rd degree: destroys all layers of skin. Requires a skin graft. Systemic effects: large loss of water, plasma, infection, reduced immune response.