Ch4 Dermis

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Ch4 Dermis

  1. 1. Chapter 4 Skin and Body Membranes “The Dermis”
  2. 2. <ul><li>Dermis </li></ul><ul><li>Two layers </li></ul><ul><ul><li>1. Papillary layer </li></ul></ul><ul><ul><ul><li>Projections called dermal papillae </li></ul></ul></ul><ul><ul><ul><li>Pain receptors </li></ul></ul></ul><ul><ul><ul><li>Capillary loops </li></ul></ul></ul><ul><ul><li>2. Reticular layer </li></ul></ul><ul><ul><ul><li>Blood vessels </li></ul></ul></ul><ul><ul><ul><li>Glands </li></ul></ul></ul><ul><ul><ul><li>Nerve receptors </li></ul></ul></ul>
  3. 3. <ul><li>Skin Structure </li></ul>
  4. 4. <ul><li>Normal Skin Color Determinants </li></ul><ul><li>Melanin </li></ul><ul><ul><li>Yellow, brown or black pigments </li></ul></ul><ul><li>Carotene </li></ul><ul><ul><li>Orange-yellow pigment from some vegetables </li></ul></ul><ul><li>Hemoglobin </li></ul><ul><ul><li>Red coloring from blood cells in dermis capillaries </li></ul></ul><ul><ul><li>Oxygen content determines the extent of red coloring </li></ul></ul>
  5. 5. <ul><li>Appendages of the Skin </li></ul><ul><li>Sebaceous glands </li></ul><ul><ul><li>Produce oil </li></ul></ul><ul><ul><ul><li>- Lubricant for skin </li></ul></ul></ul><ul><ul><ul><li>- Kills bacteria </li></ul></ul></ul><ul><ul><li>Most with ducts that empty into hair follicles </li></ul></ul><ul><ul><li>Glands are activated at puberty </li></ul></ul>
  6. 6. Nerve Receptors <ul><li>Free nerve endings </li></ul><ul><li>detect temp, mechanical stimuli (such as pressure), pain , & touch </li></ul><ul><li>Meissner’s corpuscles </li></ul><ul><li>Tactile, light touch, found in abundance in fingertips, palms, soles, lips, tongue, face, genitals. In dermal papillae. </li></ul><ul><li>Pacinian corpuscles </li></ul><ul><li>Deep, pressure, adaptive </li></ul>
  7. 7. <ul><li>Appendages of the Skin </li></ul><ul><li>Sweat glands </li></ul><ul><ul><li>Widely distributed in skin </li></ul></ul><ul><ul><li>Two types </li></ul></ul><ul><ul><ul><li>1. Eccrine </li></ul></ul></ul><ul><ul><ul><ul><li>Open via duct to pore on skin surface </li></ul></ul></ul></ul><ul><ul><ul><li>2. Apocrine </li></ul></ul></ul><ul><ul><ul><ul><li>Ducts empty into hair follicles </li></ul></ul></ul></ul>
  8. 8. <ul><li>Sweat and Its Function </li></ul><ul><li>Composition </li></ul><ul><ul><li>Mostly water </li></ul></ul><ul><ul><li>Some metabolic waste </li></ul></ul><ul><ul><li>Fatty acids and proteins (apocrine only) </li></ul></ul><ul><li>Function </li></ul><ul><ul><li>Helps dissipate excess heat </li></ul></ul><ul><ul><li>Excretes waste products </li></ul></ul><ul><ul><li>Acidic nature inhibits bacteria growth </li></ul></ul><ul><li>Odor is from associated bacteria </li></ul>
  9. 9. <ul><li>Appendages of the Skin </li></ul><ul><li>Hair </li></ul><ul><ul><li>Produced by hair bulb </li></ul></ul><ul><ul><li>Consists of hard keratinized epithelial cells </li></ul></ul><ul><ul><li>Melanocytes provide pigment for hair color </li></ul></ul>Figure 4.7c
  10. 10. <ul><li>Hair Anatomy </li></ul><ul><li>Central medulla </li></ul><ul><li>Cortex surrounds medulla </li></ul><ul><li>Cuticle on outside of cortex </li></ul><ul><ul><li>-Most heavily keratinized </li></ul></ul>
  11. 11. <ul><li>Associated Hair Structures </li></ul><ul><li>Hair follicle </li></ul><ul><ul><li>Dermal and epidermal sheath surround hair root </li></ul></ul><ul><li>Arrector pilli </li></ul><ul><ul><li>Smooth muscle </li></ul></ul><ul><ul><li>Goose bumps </li></ul></ul><ul><li>Sebaceous gland </li></ul><ul><li>Sweat gland </li></ul>
  12. 12. <ul><li>Appendages of the Skin </li></ul><ul><li>Nails </li></ul><ul><ul><li>Scale-like modifications of the epidermis </li></ul></ul><ul><ul><ul><li>- Heavily keratinized </li></ul></ul></ul><ul><ul><li>Stratum basale extends beneath the nail bed </li></ul></ul><ul><ul><ul><li>- Responsible for growth </li></ul></ul></ul><ul><ul><li>Lack of pigment makes them colorless </li></ul></ul>
  13. 13. <ul><li>Nail Structures </li></ul><ul><li>Free edge </li></ul><ul><li>Body </li></ul><ul><li>Root of nail </li></ul><ul><li>Eponychium – proximal nail fold that projects onto the nail body </li></ul>

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