Why do women require more Vitamin D and Calcium supplements than Men? 1. When women are pregnant, the body takes away the calcium from their bones and uses that to build the skeleton of the baby. 2. This leaves the women’s bones weaker. Women who have a lot of babies may develop Osteoporosis when they get older - a disease in which bones become fragile and more likely to fracture. 3. Therefore women should supplement their diet with Vitamin D and calcium to keep their bones strong. They should also have fewer babies when they start their own families. Explain the mechanism behind evolution of different skin tones in humans using simple words. 1. Early Human Beings developed in the lands around the Equator – i.e. African continents. 2. The Sun’s radiation is most intense near the equator and its strength fades away as you move towards poles. 3. The Sun’s radiation has the following components: 4. UVC is the most energetic of the ultraviolet radiation. It can cause cancer but is fortunately it is blocked by the Ozone Layer in the atmosphere at all places on earth. 5. UVB causes the production of melanin in the skin. UVB is also responsible for production of Vitamin D. UVB helps convert a chemical called 7-dehydrocholesterol in our body to Vitamin D. 6. UVA is the least energetic of the radiation. It causes melanin to turn brown which in turn causes your skin to turn darker but only temporarily. 7. In areas near the equator, there is plenty of UVB radiation. We need only some of it to produce Vitamin D. So the rest of it needed to be blocked by production of Melanin. Melanin turns the skin darker. 8. In areas near the poles, the suns radiation had to pass through the atmosphere at an inclined angle. This causes the Ozone Layer to absorb UVB radiation too. 9. When people migrated in areas near to the north and south poles, they were at risk of developing Vitamin D deficiency which in turn would lead to weaker bones. 10. So the skins of the human beings who lived near the poles turned lighter to allow scare UVB radiation to penetrate the skin and produce vitamin D. 11. On a daily basis when exposed to a lot of sun, the UVA causes our skin to turn a shade darker (called tanning) but only temporarily. When we spend a lot of time indoors, the skin returns to its original shade. People with darker skin colour (like Africans) face a risk of Vitamin D deficiency if they move to countries like USA, UK or Russia and spend all the times indoors. People from Europe who have lighter skin colour face a risk of skin burn if they move to Africa and spend all the time out in the Sun. This video explains it better: ted/talks/nina_jablonski_breaks_the_illusion_of_skin_color?language=en
Posted on: Sun, 25 Jan 2015 13:17:11 +0000
Trending Topics
Recently Viewed Topics
© 2015