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Lecture 5.2: Integumentary System

Lecture 5.2: Integumentary System. Epidermis and Vitamin D3. UV rays cause cholesterol-like steroid to change to vitamin D3 Decreased Vitamin D leads to abnormal bone growth. Skin Cancer. Most common cancer Most people survive Treatment = removal of tumor Melanomas—extremely dangerous

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Lecture 5.2: Integumentary System

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  1. Lecture 5.2: Integumentary System

  2. Epidermis and Vitamin D3 • UV rays cause cholesterol-like steroid to change to vitamin D3 • Decreased Vitamin D leads to abnormal bone growth

  3. Skin Cancer • Most common cancer • Most people survive • Treatment = removal of tumor • Melanomas—extremely dangerous • Usually begin as mole • Grow rapidly • Spread via lymphatic system

  4. Figure 5.4

  5. Dermis—Layers • Papillary Layer • Supports and nourishes epidermis • Capillaries and nerves for skin surface are here • Reticular Layer • Elastic fibers for elasticity • Collagen fibers limit elasticity for protection

  6. Figure 5.2

  7. Other Dermal Components • Hair Follicles • Sweat Glands

  8. Figure 5.1

  9. Subcutaneous Layer • Increased adipose cells • Decreased heat loss in infants • Energy reserve • Shock absorber

  10. Figure 5.1

  11. Hair • Everywhere except: • Sides and soles of feet • Palms • Sides of fingers/toes • Lips • Parts of genitalia

  12. Hair cont… • Hair follicles—where hair is produced • Hair papillae—where vessels and nerves are • Hair root—anchors hair into skin • Hair shaft—what we see • Cuticle—surface layer of hair • Grows about 0.3 mm/day • May become inactive for awhile

  13. Figure 5.5b

  14. Hair cont… • Round hairs = straight hair • Flattened hairs = curly hair • Functions • Protect from UV rays • Cushion light blows • Insulate • Prevent entry of pathogens

  15. Hair cont… • Sensory nerve fiber at base • Arrectorpili—bundle of smooth muscle • Causes hair to stand up • “Goosebumps”

  16. Figure 5.5b

  17. Hair Color • Due to amounts of pigment produced by melanocytes • Due to genetics • Pigment production decreases with age • No pigment = white hair

  18. Hair Loss • Average about 50 hairs/day • More than 100 hairs/day = hair loss • Temporarily due to: • Drugs • Diet • Radiation • High Fever • Stress • Pregnancy

  19. Sebaceous Glands • AKA: Oil Glands • Secrete into hair follicle • Sometimes onto skin • Secreted through arrectorpili • Sebum—secretion of oil • Lubricates hair and skin • Inhibits bacteria • High amounts at puberty • Acne—sebaceous duct blocked • Secretions accumulate • Causes pimples

  20. Figure 5.7

  21. Sweat Glands • Apocrine Glands • Secrete into armpits, nipples and groin • Sticky, cloudy, odorous secretion • Starts at puberty • Odorous when bacteria feed on sweat

  22. Figure 5.7

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