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The integumentary system

The integumentary system. Protection Thermoregulation Indicator of health Hypoxia Rashes Disorders of the skin. Functions of the skin. Regulation of body temperature Large blood supply (associated with thermoregulation) Protection Sensation (cutaneous receptors)

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The integumentary system

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  1. The integumentary system • Protection • Thermoregulation • Indicator of health • Hypoxia • Rashes • Disorders of the skin

  2. Functions of the skin • Regulation of body temperature • Large blood supply (associated with thermoregulation) • Protection • Sensation (cutaneous receptors) • Excretion and absorption • Vitamin D synthesis

  3. Largest organ of the body • epidermis= epithelial tissue • Dermis=connective tissue • Hypodermis(subcuta-neous layer)=areolar and adipose tissue • Hypodermis attaches to underlying tissues

  4. Epidermis • Keratinocytes • 90% of epithelial cells • Protection, durability • Melanocytes • Melanin protects against UV • Langerhans cells • Immune cells • Merkel cells • touch

  5. Epithelial layers (strata) • Stratum basale (stratum germinativum) new cell formation; keratinocytes • Stratum spinosum “spiny” • Stratum granulosum- cells are dying; producing keratin and lipid • Stratum lucidum- only in thick skin. Lots of keratin • Stratum corneum- many layers of dead cells; water repellent

  6. Dermis • Contains lots of collagen and elastic fibers • Papillary region (areolar) • Meissner corpuscles (touch) • Free nerve endings • Reticular region (dense) • variety of cells and glands • Epidermal ridges form fingerprints

  7. Lines of cleavage indicate orientation of collagen

  8. Skin color • People have same number of melanocytes but different amount of melanin • Carotene- yellowish tint • Hemoglobin-reddish tint • Albinism- no melanin • Vitiligo- irregular loss of melanin • Changes in skin tone may be significant • Cyanosis • Jaundice • Rash

  9. Accessory structures of skin

  10. Hair • Dead, keratinized cells • Medulla, cortex, cuticle • Shaft is what you see • Bulb is base of hair follicle • Papilla contains blood vessels • Matrix source of new cells

  11. Hair growth is cyclical • Lanugo formed (and lost) before birth • Vellus hairs (“peach fuzz”) • Terminal hairs • Head, eyebrow, lashes, pubic • More terminal hair on body in males than females • Hair color, balding patterns are inherited

  12. Glands of the skin sudoriferous

  13. Earwax is produced by modified sweat glands! • Ceruminous glands • Secrete into external auditory meatus • Helps protect ear from foreign objects

  14. Nails • Freeedge, nail body, nail root • Hyponychium holds nail onto fingertip • Eponychium is cuticle

  15. Skin is not uniform over the body • Thin hair is hairy • No stratum lucidum • Few epidermal ridges • Hair follicles present • Many sebaceous, fewer sudoriferous glands • Thick skin is hairless • More sensory receptors, more sweat glands

  16. Blood supply to integumentary system • None to epidermis • Some plexuses supply blood to dermis; usually offshoot of supply to muscle • Cutaneous plexus between dermis and subQ • Papillary plexus extends into dermis

  17. Developmental aspects of integument • Epidermis formed from ectoderm, dermis from mesoderm • See Figure 5.8 for sequence • Effects of aging usually occur in dermis • Collagen and elastic fibers break down • Immune function decreases • Glands secrete less

  18. Disorders of, damage to skin

  19. Damage to skin may be diagnostic • Wheal (hives) • Vesicles (viral infections) • Dermatitis, pruritis (allergic reaction) • Type of rash may help diagnose infectious disease • Condition of nails or hair may indicate disease • Contact dermatitis

  20. Introducing material to skin (barrier properties of skin) • Intradermal- within dermis • TB tests • Allergy tests • Economical way to give vaccines? • Subcutaneous • Little blood supply • Slow absorption, e.g. insulin • Intramuscular • Large doses • Rapid absorption • Transdermal • Timed release • No needles!

  21. Summary • Skin protects the internal structures • Skin helps maintain body temperature • Storage (of fat) secretion (of salts, water and wastes) and synthesis (of vitamin D) are important features • Many different types of nerve endings allow distinction of touch, pressure, pain and temperature.

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