1. Chapter 16 Nutrition and Metabolism

2. DEFINITIONS
Nutrition—food, vitamins, and minerals that are ingested and assimilated into the body
Metabolism—process of using food molecules as energy sources and as building blocks for our own molecules
Catabolism—breaks food molecules down, releasing their stored energy; oxygen used in catabolism
Anabolism—builds food molecules into complex substances

3. ROLE OF THE LIVER Secretes bile, which breaks down large fat globules
Helps maintain normal blood glucose level
Helps metabolize carbohydrates, fats, and proteins; synthesizes several kinds of protein compounds
Removes toxins from the blood

4. NUTRIENT METABOLISM Carbohydrates—preferred energy food of the body
Three series of chemical reactions in glucose metabolism
Glycolysis
Changes glucose to pyruvic acid
Anaerobic (uses no oxygen)
Yields small amount of energy (transferred to ATP)
Occurs in cytoplasm
Citric acid (Krebs) cycle
Changes pyruvic acid to carbon dioxide
Aerobic (requires oxygen)
Yields large amount of energy (mostly as high energy electrons)
Occurs in mitochondria
Electron transfer system
Transfers energy from high energy electrons (from citric acid cycle) to ATP molecules
Located in mitochondria

5. NUTRIENT METABOLISM Carbohydrates (cont.)
Carbohydrates are primarily catabolized for energy (Figure 16-1), but small amounts are anabolized by glycogenesis (a series of chemical reactions that changes glucose to glycogen—occurs mainly in liver cells where glycogen is stored)
Adenosine triphosphate (ATP)—molecule in which energy obtained from breakdown of foods is stored; serves as a direct source of energy for cellular work (Figure 16-2)
Blood glucose (imprecisely, blood sugar)—normally stays between about 80 and 110 mg per 100 mL of blood during fasting; insulin accelerates the movement of glucose out of the blood into cells, therefore decreases blood glucose and increases glucose catabolism
Fats—catabolized to yield energy and anabolized to form adipose tissue (Figure 16-3)
Proteins—primarily anabolized and secondarily catabolized

9. VITAMINS AND MINERALS
Vitamins—organic molecules that are needed in small amounts for normal metabolism (Table 16-2)
Minerals—inorganic molecules found naturally in the earth, required by the body for normal function (Table 16-3)

10. METABOLIC RATES
Basal metabolic rate (BMR)—rate of metabolism when a person is lying down but awake and not digesting food and when the environment is comfortably warm
Total metabolic rate (TMR)—the total amount of energy, expressed in calories, used by the body per day (Figure 16-4)

12. BODY TEMPERATURE
Hypothalamus—regulates the homeostasis of body temperature (thermoregulation) through a variety of processes
Skin—can cool the body by losing heat from the blood through four processes: radiation, conduction, convection, evaporation (Figure 16-5)