Chapter 5 The Integumentary System

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Chapter 5 The Integumentary System

  1. 1. Chapter 5 The Integumentary System Related topics Dermatology, acne, tanning, aging, balding, tattooing, skin cancer, massage, appearance, smell, etc.
  2. 2. Layers of Skin • Epidermis – stratified squamous keratinized epithelium • Dermis – connective tissue • (Hypodermis – CT) (5.1)
  3. 3. Functions of Skin • Protection – Cushioning – Insulation (hot – cold) – Barrier to chemicals, infectious agents, toxins – Waterproof covering – dehydration • Temperature Regulation – Capillaries & sweat glands • Excretion – Sweat glands • Block UV rays • Synthesize vitamin D • Sensory Receptors
  4. 4. Epidermis • Keratinocytes • Connected by desmosomes • Continuous turnover (35-45 days) • Mitosis at basement membrane • Superficial keratinized layer • Free nerve endings 5.3b
  5. 5. Epidermis • Thick skin – Palms & soles – Thick superficial layer • Thin skin – Everywhere else 5.4ab
  6. 6. Stratum Basale • Keratinocyte stem cells (mitotic) • One cell layer • Melanocytes produce melanin and transfer to keratinocytes – Stimulated by UV 5.3b
  7. 7. Stratum Spinosum • Keratinocytes attached by desmosomes (why?) • Many cell layers • Why is it called “spiny”? 5.3b
  8. 8. Stratum Granulosum • Keratinocytes with keratohyalin granules 5.3b
  9. 9. Stratum Corneum • Dead keratinocytes (plasma membrane + keratin) 5.3b
  10. 10. Dermis Components • CT cells: fibroblasts, macrophages, mast cells, wbcs • Fibers: collagen, elastic, reticular • Nerves & blood vessels • Skin derivatives (5.1)
  11. 11. Papillary Layer • Superficial 20% • Areolar CT • Dermal papillae • Capillary beds • Sensory nerve endings (5.1)
  12. 12. Reticular Layer • Deep 80% • Dense irregular CT • Location of: – Sensory receptors – Sweat glands & ducts – Hair follicles & roots – Blood vessels – Arrector pili muscles (5.1)
  13. 13. Hypodermis • (aka superficial fascia, subcutaneous layer) • Underneath skin • Adipose and areolar CT • Attached to muscle • Insulates (5.1)
  14. 14. Skin Color • Melanin pigment – From melanocytes – To keratinocytes – Variations • Yellow-red- brown-black 5.3b
  15. 15. Skin Color • Carotene – From plant foods • vegetables (such as carrots, tomatoes, kale, spinach, winter squashes, broccoli and romaine lettuce) and fruits (including apricots, tangerines, watermelon, cantaloupe and grapefruit). – Yellow-orange • excess carotene accumulates over a period of weeks in the skin, primarily on the palms of hands and feet, lending a yellow-orange hue
  16. 16. Can your skin turn orange if you eat too many carrots? We plan to answer that question as I go on a carrot diet for thirty days. www.steelgirl.com/carrot3.htm
  17. 17. Skin Color • Hemoglobin – Oxygenated Hb in dermis – Red – Cyanosis – blue color of poorly oxygenated Hb
  18. 18. Cyanosis http://www.lf2.cuni.cz/Projekty/interna/foto/014/pic00011.jpg
  19. 19. Hair • Shaft and root • Keratinized cells • Function: light touch • Pigment transferred from melanocytes (5.1)
  20. 20. Hair Follicle • Extension of epidermis around hair root • Located in dermis • Root hair plexus • Hair bulb • Arrector pili muscle 5.5c
  21. 21. Sebaceous Glands • Simple alveolar gland • Duct to hair follicle • Sebum – lipid secretion • Holocrine secretion – cell fragments (5.1)
  22. 22. Sweat Glands • Simple tubular gland • Water, salts, wastes • Cools body surface • Eccrine sweat glands – All over body surface • Apocrine sweat glands – Axilla, anus, genitals – 2° sex characteristics – BO/deodorant (5.1)
  23. 23. Skin Cancer • Basal cell carcinoma – least malignant, most common • Squamous cell carcinoma – keratinocytes in stratum spinosum • Melanoma – metastasize rapidly http://www.pueblo.gsa.gov/cic_text/health/skin-cancer/skin2a.gif http://www.mskcc.org/mskcc/shared/graphics/melanoma.jpg

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