1. Show Figure 47.1 and discuss the primitive digestive tube.

2. Discuss the general tube-within-a-tube design for most animals and emphasize the fact that the GI tract is outside the body and that nutrients must cross the intestinal wall to enter the body.

3. Mention the three major digestive glands: the salivary glands, the pancreas, and the liver.

1. Show Figures 47.2—47.4 and review feeding mechanisms, structures, and mouth designs.

1. Show Figure 47.5 and discuss the use of the gizzard for grinding food; add to this a list of other ways that other animals break their food, including tearing and chewing with teeth (Figures 47.6 and 47.7).

2. Discuss the crop and the stomach as storage organs and ask students to provide ideas on the adaptive significance of these structures, which allow animals to eat now and digest later.

1. Show Figure 47.8 and describe the four GI tract tissue layers.

2. Show prepared microscope slides of each tissue type and discuss how the tissue's form relates to its function.

3. Show Figures 47.9 and 47.10 and discuss how the bolus is formed and moved to the stomach by peristalsis.

4. Continue tracing the path of food through the GI tract and explaining the role of various organs along the way.

1. Show Figure 47.11 and discuss the enzymes that break down carbohydrates.

1. Discuss the role of proteases and where they are secreted, and show Figure 47.12.

2. Mention that the pancreas secretes bicarbonate solution to neutralize stomach acid in the small intestine so that enzymes work more effectively.

3. Review Concepts 47.1 and list and define the functions of the cell types found in the GI tract of mammals.

1. Review Concepts 47.2, liver functions.

2. Discuss the hepatic duct system and show a picture or diagram of the liver, gallbladder, small intestine, and the associated ducts.

1. Show Figure 47.18 and emphasize the importance of the villi and surface/volume ratio.

2. Show Figure 47.19 and discuss how this ratio is increased dramatically by the microvilli.

3. Show prepared slides of villi and microvilli cross sections.

4. Review surface/volume ratio in the brain to remind students that the small intestine is another example of a folded tissue surface that results in greatly increased absorption area.

1. Discuss how glucose is converted to triglycerides and stored as fat in adipose tissue (Table 47.1).

1. Discuss the digestive products formed from fats and phospholipids.

2. Cover high-density, low-density, and very-low-density lipoproteins and show Figure 47.22.

3. Discuss atherosclerosis and other diseases associated with diets that are high in LDLs.

1. Discuss the metabolic phases associated with digestion of food and its movement through the GI tract and show Figure 47.23 to summarize this.

1. Show Figure 47.24 as a summary of the major points presented so far and to introduce this section on hormone regulation.

2. Review the functions of insulin and glucagon, along with epinephrine, growth hormone, and cortisol.

3. Bring in recent articles covering the use of growth hormone to reverse the aging process and ask students to propose ideas on how this works with regard to metabolism.

1. Discuss the important roles of iron and how it is transported in the blood, as shown in Figure 47.27.

2. List storage sites for iron and discuss how it is used in the bone marrow.

3. Discuss the formation and elimination of bilirubin and biliverdin.

4. Cover jaundice and its causes.

5. Show a periodic table and highlight all the elements that have been discussed to this point, emphasizing the importance of trace elements.

6. Do a demonstration on how iron is consumed in iron-fortified cereal: add water to Total® brand cereal, wait for it to become soggy, stir it up, then pull iron particles out of it using a large magnet.

1. Stress the high turnover rate of calcium in human blood and use this to open a discussion of osteoporosis and the importance of consuming calcium.

1. Show Figure 47.28 to introduce the idea of maintaining a proper balance of nitrogen and the addition of essential amino acids to the diet.

2. Discuss or have students research cooking methods used in various cultures and their role in supplementing the diet with amino acids.

1. Show Table 47.3 and discuss modern eating habits and how they vary from those of our ancestors.