The Human Relationship With Uv Radiation Is Complicated Uv Radiation Does Provide A Benefit To Humans As The Skin Abso 1 (39.79 KiB) Viewed 11 times
The Human Relationship With Uv Radiation Is Complicated Uv Radiation Does Provide A Benefit To Humans As The Skin Abso 2 (38.48 KiB) Viewed 11 times
The human relationship with UV radiation is complicated. UV radiation does provide a benefit to humans. As the skin absorbs it, a complicated process occurs that leads to the production of Vitamin D. This vitamin facilitates calcium ion absorption from the blood for storage in the bone, or use in various physiological processes. When humans lived in low latitude regions, the Vitamin D production was not a problem as exposure to UV radiation was significant. However, as people with significant eumelanin moved north, the ability to product Vitamin D declined, which lead to rickets and other diseases involving calcium deficiencies. In these people, a change in the MC1R gene lead to production of pheomelanin, which resulted in lighter skin that could make use of the limited amount of UV radiation available. A healthy body is a balancing act between the need to absorb and the need to avoid UV radiation.
Serum total 25(OH)D, nmol/L 0 0 70 0 50 40 38 20 10 0 7 1-5 6-11 B 20-49 12-19 HE 50-59 260 Male Female Age, y Sex vitamin D in the blood of Americans. NHB Hisp ΜΗΝ Race-ethnicity Figure 3Levels of Serum total 25(OH)D, nmol/L means the amount of vitamin D in the blood. 1. Using the graph above, rank the three race/ethnicity groups in terms of Vitamin D production. 2. Explain why the group with the least Vitamin D production is so low. 3. Which of the three groups listed above is most likely to show a folate deficient? Explain. 4. Native people living north of the Arctic Circle tend to have darker hair and skin than those living in the high latitude regions south of the Arctic Circle. How is this possible?
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