Describe the lining of the small intestine and how its structure is related to its function
The intestinal tract lining is composed of a single sheet of cells, and the sheet pokes out into millions of finger-shaped projections called villi. Each villus has its own capillary network and a lymph vessel so that as nutrients move across the cells, they can immediately mingle into the body fluids. Every villus cell has a brush-like covering of tiny hairs, called microvilli, which can trap nutrient particles.
The lining of the small intestine, villi and all, is wrinkled into thousands of folds, making its absorbent surface area enormous. If the folds and the villi that cover them were spread out flat, the total area would equal the size of a tennis court. The billions of cells of that surface, although they weigh only 4 to 5 pounds total, absorb enough nutrients in a few hours a day to nourish the other 150 or so pounds of body tissues.
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Which of the following factors can increase LDL-cholesterol?
A) Plant stanols and sterols intakes B) Whole grains intake C) Physical activity D) Trans fats and saturated fats intakes
What percentage of the average American's income is spent on what he or she eats today?
A) over 25 percent B) less than 5 percent C) 20 percent D) less than 10 percent
Milk is not a significant source of _____
a. riboflavin b. vitamin D c. vitamin C d. protein e. potassium
Each of the following is known to be linked to excessive intake of fats EXCEPT
a. cancer. b. obesity. c. heart disease. d. lactose intolerance.