Chapter 7, Problem 12RQ

When William H. was helping victims after a devastating earthquake in a region not prepared to swiftly set up adequate temporary shelter, he developed severe diarrhea. He was diagnosed as having cholera, a disease transmitted through unsanitary water supplies contaminated by fecal material from infected indiv iduals. The toxin produced by cholera bacteria causes Cl- channels in the lurninal membranes of the intestinal cells to stay open, thereby increasing the secretion of Cl- from the cells into the intestinal tract lumen. By what mechanisms would Na+ and water be secreted into the lumen in conjunction with Cl- secretion? How does this secretory response account for the severe diarrhea that is characteristic of cholera?

Which of the following statements is not true? a. Essential nutrients can be synthesized by the body. b. Vitamins are required in small quantities for bodily function. c. Some amino acids can be synthesized by the body, while others need to be obtained from diet. d. Vitamins come in two categories: fat-soluble and water-soluble.

The food label in Figure 11.28 lists the nutrients and other substances in a package of ready-to-eat macaroni and cheese. Based on your reading in this chapter, how would you rate this products healthiness in terms of fats and carbohydrates? Figure 11.28 Food labels are useful health tools. Information on a food label can be used to ensure that you get the nutrients you need without exceeding recommended limits on less healthy substances such as salt, sugar, and trans fats. At present, the USDA is considering major revisions to food labels. The proposed changes include showing realistic serving sizes and sugars added by the manufacturer, and printing the calorie content per serving in larger, bolder type so that it is easier for consumers to make informed choices about purchases of prepared foods. (Left: USDA, US Department of Agriculture; Right: FoodCollection/SuperStock)