Thursday, July 15, 2010

Chapter 2

9. Why do we need Vitamin D? Cholesterol? Folic acid?

Vitamin D is essential for bone growth in children and or the maintenance of healthy bones for adults. The vitamin makes sure to regulate phosphorus and calcium levels in blood. Lacking the necessary levels of vitamin D directly cause osteoporosis in adults and rickets in children, which both branch out to other diseases. Proper functioning of the immune system, nervous system, and process of clotting all rely on vitamin D. Not only is cholesterol needed to create and maintain cell membranes, but it also sends messages from the brain, fights diseases and infections alongside the immune system, and produce estrogen and testosterone. Furthermore, cholesterol can be converted into vitamin D when the skin is exposed to ultraviolet B (UVB) light. Last, folic acid is a vital component to cell growth due to it function of replicating DNA when cells undergo cell division. A lack of folic acid during a pregnancy may cause physical deformities to a fetus. Additionally, individuals who lack folic acid or folate may contract anemia because the necessary acid produces red blood cells.

10. Briefly describe the connection between the two concepts.
a. While tanning, ultraviolet rays are exposed and often absorbed the skin. UV rays destroy folic acid within the body, which means that cell growth cannot prosper without the ability to replicate DNA during mitosis. A lapse in cell growth can cause birth defects in women who go tanning and expose themselves to UV rays when pregnant.

b. While wearing sunglasses, an individual is more likely to get a sunburn. The tanning process begins with the optic nerve sensing sunlight and informing the pituitary gland to unleash hormones that boost the melanocytes within the body. This causes an excessive production of melanin. This process can easily be inhibited when wearing sunglasses, because the optic nerve cannot sense as much sunlight, causing the miniscule melanin production due to quickly cause a sunburn after a period of time.

c. Research shows that African Americans are highly vulnerable to hypertension and answer the data by looking at the past, particularly the slave trade. The gruesome journey that was imposed by slave traders forced Africans in terrible conditions that caused much of the passengers to die. Those with higher levels of sodium in their body had the ability to avoid life-threatening dehydration and had a better chance to survive. When the evolutionary advantage combines with modern diets that are sodium-enriched, hypertension is easily distinguishable in African-Americans.

d. Asian flush is caused by certain enzymes that enable tolerance to alcohol. The presence of such genetic variations can be traced back to practices that were used to obtain clean water. European civilizations used the process of fermentation, which killed the bacteria in water and enabled a higher tolerance for the consumption of the substance and the ability to detoxify it. On the other hand, Asian communities cleansed their water by boiling it and transforming it into tea. Thus, Asians were not under evolutionary pressure to drink alcohol in order to drink clean water, which meant that they did not have a high tolerance to alcoholic beverages.

e. Skull shape is affected by climate in the sense that scientists believe that the shape depends on how much heat must be stored and released in a particular region.

f. Dense and thick body hair, especially on the forearms and legs, are regarded as a natural defense to ward off mosquitoes that carry malaria.

11. What’s so fishy about the Inuit’s skin?

Inuits are a dark-skinned population that recieve a very limited amount of sunlight. Evolving to have lighter skin in order to obtain more vitamin D from the sun is completely unecessary for the Inuits because they eat a great amount of fish that have an abundance of vitamin D.

12. Explain the good and bad of ApoE4.

If an individual is adequately exposed to sunlight, then they have the benefit of having excess cholesterol that can be easily converted into vitamin D. If sunlight is not present, cholesterol builds up and clings to arteries. Excessive build up can lead to a blockage that causes a heart attack or stroke.

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