Human Nutrition

1. Do carbohydrates have their origin in plants or animals? What is the process by which carbohydrates are first made? See fig 4.4 for reference.
2. How can glucose be used by the cells of the body?
3. Glycogen is stored in which two tissues of the body? What is the purpose of each storage location?
4. What are some of the health benefits attributed to fiber in the diet?
5. Briefly define diabetes (take note of the heading on p92). What is the effect of diabetes on the levels of blood sugar? What are some complications of diabetes?
6. What is going on with insulin in each type of diabetes?
   type I- type II-
7. What is the major risk factor for type II diabetes?

Analysis

1. Starch and cellulose are storage forms of glucose in plants. The human digestive tract can digest starch, but not cellulose, due to a structural difference between them. Fig. 4.6 shows that both starch and cellulose are long chains glucose molecules linked together. Is the structural difference between starch and cellulose based in the glucose molecules they are made of, or the bonds that hold the glucose molecules together?
2. The liver takes in glucose from the bloodstream and stores it in the form of glycogen when the body is fed. During fasting the reverse occurs. The liver breakdown glycogen and releases glucose back into the bloodstream. These process are controlled by the hormones insulin and glucagon. In the diagram below write “insulin” and “glucagon” above or below the proper arrow.

Glucose in the bloodstream glycogen stored in the liver

1. Fig. 4.13 illustrates the processes by which cells get energy (ATP) from glucose. In simplest terms, what do cells do to the structure of glucose that releases energy? What molecule does the energy of glucose get transferred to? What other molecules are produced in the process?
2. What does fig. 4.14 tell us about the relationship between carbohydrate and fatty acid metabolism? What two molecules are central to this relationship?
3. According to fig. 4.12, what tissues in the body respond to insulin? How do these tissues respond?
4. Carbohydrate is said to spare protein. What does this mean?