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Ch. 5 integumentary system buchanan (with updates)


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Chapter 6: Integument

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Ch. 5 integumentary system buchanan (with updates)

  1. 1. Chapter 6Integumentary System
  2. 2. I. Introduction A. Organs are composed of two or more kinds of tissues B. Largest organ of the body is the skin (“Integumentary System” includes skin, hair, nails & glands)
  3. 3. II. Functions of the Integumentary System A. Protection = skin protects against abrasion, UV light, microorganisms, dehydration B. Sensation = sensory receptors detect heat, cold, touch, pressure, & pain C. Vitamin D production = skin produces a molecule that can be transformed into vitamin D when exposed to UV light D. Regulates body temperature = body temperature controlled by blood flow through skin and sweat gland activity E. Excretion = small amounts of waste lost through skin/gland secretions
  4. 4. III. Layers of the Integument A. Hypodermis (“under + skin”) or Subcutaneous (“below + skin”) 1. Attaches skin to underlying bone and muscle 2. Supplies skin with blood vessels & nerves 3. Not part of the skin 4. Composed of loose connective & adipose tissue a. Padding & insulation b. Sex differences c. Total body fat estimates made from pinching hypodermis 5. Site of subcutaneous injections
  5. 5. B. Skin = Dermis + epidermis  Dermis = layer of dense connective tissue  Epidermis = (upon the dermis) layer of epithelial tissue resting on dermis a. Hypodermis = foundation of house b. Dermis = house c. Epidermis = roof
  6. 6. 1. Dermisa. Connects epidermis to underlying connective tissueb. Composed of collagen, elastic fibers, fibroblasts, fat cells, & macrophages (fewer fat cells & blood vessels than hypodermis) i. Collagen fiber orientation can either resists or be susceptible to stretching (cleavage/tension lines) – Figure 5.2
  7. 7. c. Nerve endings, hair follicles, smooth muscle, glands, lymphatic vessels extend into dermis (Figure 5.1)d. Dermal papillae = projections into upper dermis extending toward epidermis; contain many blood vessels (Fig. 5.3a) i. Supply epidermis with nutrients ii. Remove waste iii. Regulate body temperature iv. Found in hands & feet – fingerprints/ridges for friction and grip • Dermis is part of animal hide used in making leather • Site of injections like TB test
  8. 8. 2. Epidermis (“upon + skin”) a. Prevents water loss, injury, entrance of harmful chemicals b. Composed of stratified squamous epithelium i. Mitosis in deepest layers, pushing older cells to surface where they slough off ii. Outermost cells protect those underneath iii. Deeper replicating cells replace cells lost from the surface c. During migration from “deep” to “superficial” cells change in shape and chemical composition i. Keratinization = cells fill with keratin • Cells die and form protective layer resisting abrasion & forming permeability layer
  9. 9. d. Epidermis is stratified (strata = layer) (Fig. 5b) i. Stratum basale = base layer • Cuboidal or columnar cells – mitosis every 19 days i. Intermediate strata ii. Stratum corneum = horny layer • Mos superficial • Dead, squamous cells filled with keratin • Coated/surrounded by lipids, prevent fluid loss • 25+ layers of dead cells joined by desmosomes • Calluses (hard skin) = increase in number of layers in stratum corneum due to friction • Corn = similar reaction as callus, just over a bony prominence
  10. 10. 3. Skin color (Pigments in the Epidermis) a. Determined by pigments in skin, blood circulating in skin, thickness of stratum corneum b. Melanin (black) = group of pigments determining color of skin, hair, and eyes i. Usually brown to black, sometimes yellowish or reddish ii. Melanocytes (black cell) • Golgi bodies in melanocytes package melanin into melanosomes, then phagocytized by epithelial cells (Fig. 5.4)
  11. 11.  Large amounts of melanin in freckles, moles, genitalia, nipples, areolas Less melanin in lips, palms, soles Racial variations – due to amount, kind, and distribution of melanin All races have ~same number of melanocytes Melanin production determined by genetic factors, light exposure, hormones 1. Albinism = recessive gene for deficiency/absence of melanin 2. UV exposure stimulates melanin production = suntan 3. Pregnancy – darker nipples and areolas, genitalia, cheekbones, forehead, chest, midline
  12. 12. c. Cyanosis (dark blue color) = decrease in blood oxygend. Birthmarks = congenital disorders of capillaries in the dermise. Carotene = yellow pigment in carrots and squash, lipid soluble – Vitamin A 1. Accumulates in lipids of stratum corneum & fat in dermis and hypodermis = yellow tinted skin
  13. 13. IV. Accessory SkinA. Hair Structures 1. Characteristic of all mammals a. Thick hair = fur 2. Hair anatomy: a. Hair shaft = portion of hair above skin surface b. Hair root = portion of hair below skin surface c. Hair bulb = base of hair root d. Medulla= center of hair e. Cortex (bark) = surrounds the medulla f. Cuticle (skin) = single layer of overlapping cells holding hair follicle g. Hair follicle = extension of epidermis deep into dermis i. Plays role in tissue repair
  14. 14. 3. Hair growth: a. Cyclic: growth stage + resting stage i. Hair bulb produces hair; nourished by blood vessels ii. Epithelial cells undergo keratinization in hair bulb; cells are added to base of hair – hair “growth” iii. Growth stops during resting stage iv. Next growth stage causes hair to fall out Hair Type Growth Stage Resting Stage Eyelash 30 days 105 days Scalp 3 years 1-2 years i. Pattern baldness – permanent loss of hair3. Hair color determined by varying amounts & types of melanin a. Melanin production decreases with age = gray/white
  15. 15. B. Muscles 1. Arrector pili (that which raises, hair) = contraction of these muscles cause hair to “stand on end”… goosebumps  a. Composed of smooth muscle b. Evolutionary advantage in mammals – traps air (heat) for insulation, also look larger - intimidation
  16. 16. C. Glands1. Sebaceous glands a. Simple, branched acinar/alveolar b. Produce sebum – oily substance lubricating hair & skin surface, preventing drying out & bacterial infection
  17. 17. C. Glands, continued…2. Sweat glands (two types): a. Merocrine sweat glands i. Simple, coiled tubular w/ ducts opening to skin surface ii. Every part of skin, most abundant in palms/soles iii. Produce sweat: slightly salty water-based secretion • Evaporative cooling • Emotional stress produces sweat in palms, soles, axillae (used in lie detector tests!) b. Apocrine sweat glands i. Simple, coiled tubular with ducts opening into hair follicles of axillae & genitalia • Become active at puberty due to sex hormone influence ii. Secretes thick organic substances • Broken down by bacteria = body odor
  18. 18. D. Nails 1. distal ends of digits of primates 2. Nail = thin, horny plate at end of fingers and toes, consisting of several layers of dead epithelial cells (stratum corneum) containing a hard keratin 3. Nail anatomy: a. Nail body = visible part of nail b. Nail root = part of nail covered by skin c. Eponychium or cuticle (upon + nail) = stratum corneum extending onto nail body d. Nail bed = nail root and nail body attach to this e. Nail matrix = proximal portion of nail bed w/o nail root attached i. Produces cells that result in nail growth ii. Nails grow continuously f. Lunula = whitish, crescent-shape at base of nail
  19. 19. V. Physiology of the Integumentary SystemA. Protection 1. Prevents water loss (lipids) 2. Prevents entry of microorganisms/foreign substances (secretions & skin) 3. Protects against abrasion (stratified squamous epithelium) 4. Protects against UV light damage (melanin) 5. Hair: insulation (head), keeps foreign objects/microorganisms/sweat out (eyelashes, eyebrows, nose & ear hairs) 6. Damage protection/defense (nails)
  20. 20. V. Physiology of the Integumentary System, cont.B. Sensation 1. Nervous receptors in dermis & epidermis (pain, heat, cold, pressure)B. Vitamin D Production 1. Vitamin D precursor made in skin, modified by liver, sent to kidney were becomes vitamin D 2. Required for calcium & phosphate absorption in intestinesB. Temperature Regulation 1. Necessary for enzyme function 2. Blood vessels (arterioles) in dermis dilate to lose heat, constrict to keep it inB. Excretion 1. Removal of waste products from the body – small role 2. Sweat: water, salts, urea, uric acid, ammonia
  21. 21. VI. Integumentary System as a Diagnostic Aid Cyanosis = skin appears bluish, low oxygen in blood (indicates impaired circulatory or respiratory function) Jaundice = skin appears yellowish, liver damage causes bile pigment buildup Rashes, lesions, vitamin deficiencies, iron deficiencies
  22. 22. A. Burns 1. Partial-thickness burns – part of stratum basale viable a. First-degree burns – involves epidermis, red, painful, edema i. Sunburn, quick exposure to hot/cold ii. No scarring, heal quickly b. Second-degree burns – destruction of epidermis an dermis, recovery happens from edge of burn c. Full-thickness or third-degree burns i. Painless b/c nervous tissue destroyed ii. Whit, tan, brown, black, or deep cherry red iii. Scarring with disfiguration, extended healing time iv. Skin grafts (self, cadavers, pigs, lab-grown?)
  23. 23. B. Skin Cancer 1. Most common type of cancer (UV radiation, chemicals, radiation) 2. Basal cell carcinoma – stratum basale to dermis forming an open ulcer a. Treatment: surgery or radiation 3. Squamous cell carcinoma – cells immediately superficial to stratum basale a. Produce tumors – continue dividing, can be fatal 4. Malignant melanoma – arise from melanocytes (moles) a. Can be fatal (will metastasize)
  24. 24. VII. Effects of Aging on Integumentary Systema) Diminishing skin function due to compositional and functional changes in its layersb) Age spot = increase in number of melanocytes in some areas vs. freckles = increase in melanin production