Chapter 5 integumentary
- 1. Chapter 5 Integumentary System Joel G. Soria, MD
- 2. Integumentary What does integument mean? • covering Components: • skin • hair • nails • glands
- 4. Functions 1. Protection: water loss, microbes, UV light 2. Sensation: hot, cold, pain, pressure 3. Temperature regulation: helps maintain homeostasis 4. Excretion: removes waste 5. Vitamin D production: UV light stimulates production
- 5. Skin facts • Weighs 9 lbs. • Used to determine body fat • 2 main regions: epidermis and dermis
- 6. Epidermis 1st major skin region (outside) Composed of stratified squamous epithelium Keratinization: • process ion which new cells (with keratin) push old cells to surface
- 7. Strata of Epidermis • Stratum corneum: - outermost layer of epidermis - 20-30 layers of dead squamous cells filled with keratin - accounts for 75% of epidermal thickness - dandruff is this layer flaking off scalp • Callus: forms when stratum corneum has frequent friction • Stratum basale: - deepest layer of epidermis - single layer of cells - firmly attached to dermis
- 8. Dermis 2nd major skin region Dense connective tissue Contains collagen and elastic fibers Contains fibroblasts, nerve endings, smooth muscle, glands, blood vessels, and hair follicles
- 9. Cleavage lines: • area where skin is most resistant to stretching • due to orientation of collagen fibers • important in scarring
- 10. Layers of the Dermis • Papillary layer: - thin connective tissue layer that contains blood vessels - Dermal papillae: - projections that extend up into epidermis - remove waste and help regulate body temp. - ridged on hands and feet (fingerprints) - pattern is genetically determined • Reticular layer: deepest layer of dermis accounts for 80% of dermis
- 11. Hypodermis Below dermis Foundation of skin Attaches skin to underlying muscle and bone Contains loose and adipose tissue Contains ½ I'm 20-23%, males 13-25%
- 12. Skin color and variations • Determined by: - pigments - genetics - blood circulation - thickness of stratum corneum • Melanocytes of darker skinned people produce more and darker melanin than fairer skinned people • All races have same number of melanocytes
- 13. Skin Pigments • Melanin: - produced by melanocytes - ranges from yellow to reddish-brown to black - responsible for hair and eye color - provides protection against UV light - amt. produced determined by genetics, UV light, hormones - freckles are accumulation of melanin - albinism is absence of melanin • Carotene: - yellow-orange pigment found in plants - accumulates in stratum corneum • Hemoglobin: - gives pinkish-red color - found in red blood cells
- 15. Tanning and Sunburn • Exposure to UV light stimulates melanocytes to increase production of melanin • Melanin builds up to help protect skin against UV radiation (tan) • A sunburn is the skin reacting to UV exposure • UV light causes elastic fibers to clump and become leathery • UV light can alter DNA in cells causing them to mutate (cancer)
- 16. Skin Color and Disease • Redness: fever, hypertension, inflammation, allergies • Pallor: anemia or low blood pressure • Jaundice: liver disorder (yellow) • Bronzing: Addison’s disease (kidney disease) • Bruising: broken blood vessels
- 17. Hair Components • Hair/shaft: flexible strands of keratinized cells • Root: below skin (scalp) • Hair Bulb: - base of root - where hair is produced • Hair Follicle: - group of cells that surround root and bulb - gives hair different shapes
- 18. How is hair produced • Hair is produced in hair bulb • Hair bulb rests on blood vessels to supply it with nutrients • Hair grows longer as cells are added to base of hair bulb
- 19. Hair Facts • Testosterone and good nutrition promote hair growth • Growth occurs in cycles: active and resting • Scalp hair grows for 3 years and rests for 1 year • Eyelashes grow for 30 days and rest for 105 days • We lose about 90 scalp hairs/day • Grey hair is the loss or fading of melanin • Male pattern baldness is from the loss of the hair follicle
- 20. Hair muscles • Arrector Pili: - smooth muscle that surrounds each hair follicle - contracts and hair stands on end (goose bumps)
- 21. Glands • Sebaceous glands: - connected to hair follicle - sebum: oily substance that lubricates hair and skin to prevent drying • Eccrine sweat glands: - all over body and open into sweat pores - water and salt secretions
- 22. • Apocrine sweat glands: - open into hair follicle - only in armpits and genitalia - thick, rich secretions - become active during puberty and cause body odor
- 23. Eccrine sweat gland Sebaceous gland Arrector pili (smooth muscle) Duct of eccrine sweat gland Sweat pores Apocrine sweat gland Hair bulb Hair follicle Duct of apocrine sweat gland
- 24. Vitamin D production 1. UV light causes skin to produce a precursor molecule of vitamin D 2. Precursor is carried by blood to liver where it is modified 3. Next to kidneys where it is modified again to form active vitamin D • Vitamin D can also be ingested through fish oils, fortified milk, eggs, and butter. • Vitamin D stimulates intestine to absorb calcium and phosphate (bone growth and muscle function)
- 25. Temperature regulation • Body temp. should be 98.6oC • Rate of chemical reactions (metabolism) is altered by changes in temp. • To cool body: blood vessels in dermis dilate and heat is transferred from deep in tissues to skin and sweat is produced • Too heat body: blood vessels constrict to reduce blood flow to skin and heat is retained
- 26. Classification of Burn • 1st degree: - damages only epidermis - redness, slight swelling, pain - heals within 2-3 days (usually no scar) - includes sunburns or exposure to cold
- 28. Classification of Burn • 2nd degree: - damages epidermis and upper dermis - redness, swelling, pain, blisters - heals in 2 weeks with some scarring
- 29. Classification of Burn • 3rd degree: - destroys epidermis and dermis - burned areas are cherry red to black - nerve endings are destroyed - skin graft might be necessary