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Skin Color

Skin Color. Skin color is determined by (a) the amount of blood, (b) pigments, (c) oxygenation level of the blood, (d) all of these. Which pigments contribute to skin color? . Melanin, carotene, and hemoglobin. Melanin. Melanin is the only pigment made in the skin.

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Skin Color

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  1. Skin Color Skin color is determined by (a) the amount of blood, (b) pigments, (c) oxygenation level of the blood, (d) all of these

  2. Which pigments contribute to skin color? • Melanin, carotene, and hemoglobin

  3. Melanin • Melanin is the only pigment made in the skin. • Polymer (large macromolecule with repeating units) • Ranges in color from yellow to reddish-brown to black

  4. Human skin color • Comes in different colors • Distribution is not random – • Darker-skinned people found nearer the equator (where greater protection from the sun is needed) • Lighter-skinned people found near poles • Melanocytes of black and brown skinned people produce many more and darker melanosomes than lighter skinned people • Freckles and pigmented moles – accumulation of melanin

  5. What’s in a tan? • Melanocytes are stimulated to greater activity • Prolonged buildup of sun causes buildup of melanin • Buildup helps protect DNA of viable skin cells from UV by absorbing the light and dissipating energy as heat.

  6. The long and the short of it… • Sun's rays contain two types of ultraviolet radiation that reach your skin: UVA and UVB. • UVB radiation burns the upper layers of skin (the epidermis), causing sunburns. • UVA radiation is what makes people tan. UVA rays penetrate to the lower layers of the epidermis, where they trigger cells called melanocytesto produce melanin. Melanin is the brown pigment that causes tanning. • Melanin is the body's way of protecting skin from burning. • Darker-skinned people tan more deeply than lighter-skinned people because their melanocytes produce more melanin. But just because a person doesn't burn does not mean that he or she is also protected against skin cancer and other problems.

  7. HW: Read Homeostatic Imbalance, TB 157 bottom center • Write a summary about melanin’s protective effects – to be shared in class tomorrow.

  8. Carotene • Yellow to orange pigment found in certain plant products (carrots) • Accumulates in stratum corneum and fatty tissue of hypodermis • Obvious in palms and soles of where stratum corneum is the thickest

  9. Fair skin • Pinkish hue of fair skin reflects crimson • Color of oxygenated hemoglobin • Fair skin people have small amounts of melanin, epidermis is nearly transparent thus showing the hemoglobin color.

  10. HW: Read Homeostatic Imbalance, TB 157 bottom right • Write a summary of what you read: (to be shared in class tomorrow) • Redness or erythema • Pallor or blanching • Jaundice or yellow cast • Bronzing • Black and blue marks or bruises • hematomas

  11. And just a little more HW • TB Questions page 173 – write the question and correct answer: 1, 2, 3, 4, 5, 6, 7

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