On page 52 of his book, Moalem briefly mentions Crohn's disease, and how it plays a part in creating a deficiency of vitamin D in individuals who have it. Crohn's disease is a disorder that results in the inflammation of the small intestine, which prevents the absorption of nutrients, one of them being vitamin D. This relates to Big Idea 2, that biological systems utilize free energy and molecular building blocks to grow, reproduce, and to maintain dynamic homeostasis. Vitamin D is required by cells in order to promote growth and regulate the levels of calcium and phosphorus in our blood.
Can Crohn's disease be acquired genetically? What genes (which chromosomes) are shown to be related to Crohn's disease, and how are they different? According to Maolem, what is the relationship between cholesterol and vitamin D, and furthermore, is there any sign of negative/positive inhibition? We now know that sunlight allows us to convert cholesterol to vitamin D, but what other factors are involved? Is there a known chemical process in which we turn cholesterol to vitamin D?
Crohn's disease is a disorder that "includes significant inflammation of the small intestine"(Moalem 52). Crohn's disease mainly affects the last part of the small intestine, called the ileum, and it can also affect part of the colon along with the gastrointestinal tract (http://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/). The small intestine is a crucial part of the digestion system; it's where most of digestion occurs. Pancreatic Amylase finishes the breakdown of carbohydrates into simple sugars, Pancreatic Protease and trypsin finish the breakdown of protein into amino acids, and Pancreatic Lipase starts and finishes the breakdown of lipids into fatty acids and glycerol molecules. The digestion and absorption of nutrients in the small intestine relates to Big Idea 2 that states, "biological systems utilize free energy and molecular building blocks to grow, reproduce, and to maintain dynamic homeostasis". The small intestine is essential for the body to be able to use these molecular building blocks in order to create ATP and perform other important bodily functions.
ReplyDeleteAbsorption of vitamins and minerals also occurs in the small intestine, so this is why people who have Crohn's disease generally have vitamin D deficiencies. Vitamin D is essential for us in that it maintains a normal blood level of calcium and phosphorus in the body (http://www.mayoclinic.com/health/vitamin-d/NS_patient-vitamind). Phosphorus helps with growth, repair, and maintenance of tissues and cells, and Calcium is crucial for strong bones and teeth in the body (http://www.umm.edu/altmed/articles/calcium-000290.htm). Vitamin D and cholesterol are very much related. According to Moalem, cholesterol is part of the body's manufacturing of Vitamin D in ultraviolet B light. First, 7-dehydrocholesterol is converted into vitamin D3. Next, the liver changes vitamin D3 into hydroxyvitamin D. Lastly, the hydroxyvitamin D obtains an an oxygen and a hydrogen to become 1, 25 dihydroxyvitamin D, which is the usable form (http://www.health.harvard.edu/newsweek/vitamin-d-and-your-health.htm).
Crohn's disease can be inherited genetically. Crohn's disease is related to chromosomes 5 and 10, and the IL23R gene is the main gene that is associated with it. However, scientists have figured out that variations of the ATG16L1, IRGM, and the NOD2 genes can also cause increased susceptibility to Crohn's disease. This relates to Big Idea number 1 that states, "The process of evolution drives the diversity and unity of life". Variations, such as in this case, occur naturally in a population due to meiosis and random mutation. Certain variations are selected for and certain are selected against. The ones that are selected for are more likely to survive and reproduce, while the others are not. Scientists are unclear on the particular inheritance pattern of Crohn's disease, as there are too many genetic and environmental factors that come into play (http://ghr.nlm.nih.gov/condition/crohn-disease).
(Jeremy Bush jbush3@students.d125.org)