Psychology Chapter 24 Homework Distinguish between fat- and water-soluble vitamins

Unlock access to all the studying documents.

View Full Document

CHAPTER

Nutrition, Metabolism, and Body

Temperature Regulation

Objectives

Diet and Nutrition

1. Define nutrient, essential nutrient, and calorie.

2. List the six major nutrient categories. Note important sources and main cellular uses.

3. Distinguish between simple and complex carbohydrate sources.

4. Indicate the major uses of carbohydrates in the body.

5. Indicate uses of lipids in the body.

6. Distinguish between saturated, unsaturated, and trans fatty acid sources.

Overview of Metabolic Reactions

14. Define metabolism. Explain how catabolism and anabolism differ.

15. Define oxidation and reduction and indicate the importance of these reactions in

metabolism.

Metabolism of Major Nutrients

18. Summarize important events and products of glycolysis, the Krebs cycle, and electron

transport.

20. Describe the process by which fatty acids are oxidized for energy.

23. Describe the need for protein synthesis in body cells.

Metabolic States of the Body

24. Explain the concept of amino acid or carbohydrate-fat pools, and describe pathways by

which substances in these pools can be interconverted.

The Metabolic Role of the Liver

26. Describe several metabolic functions of the liver.

Energy Balance

28. Explain what is meant by body energy balance.

29. Describe several theories of food intake regulation.

Developmental Aspects of Nutrition and Metabolism

33. Describe the effects of inadequate protein intake on the fetal nervous system.

34. Describe the cause and consequences of the low metabolic rate typical of the elderly.

Suggested Lecture Outline

I. Diet and Nutrition (pp. 907–913; Figs. 24.1–24.2; Tables 24.1–24.3)

A. A nutrient is used by the body to promote normal growth and development.

1. Major nutrients are carbohydrates, lipids, and proteins; vitamins and minerals are

micronutrients (p. 907; Fig. 24.1).

B. Carbohydrates consist of sugars (monosaccharides and disaccharides) from fruits,

sugarcane, sugar beets, honey, and milk; and polysaccharides from grains, fruits, and

vegetables (p. 908; Table 24.1).

2. Polysaccharides, such as insoluble cellulose and other soluble polysaccharides,

provide fiber in the diet.

1. Essential fatty acids linoleic acid and linolenic acid cannot be made by the body, so

these must be consumed in the diet.

3. Lipids help the body absorb fat-soluble vitamins, serve as a cellular fuel, are an

integral component of myelin sheaths and cell membranes, form adipose tissues, and

serve as regulatory molecules.

D. Proteins that have all essential amino acids are complete proteins, and are found in eggs,

milk, fish, and meats; proteins that are low or lacking in one or more of the essential

amino acids are incomplete, and are found in legumes, nuts, and cereals (pp. 910–911;

Fig. 24.2; Table 24.1).

1. Proteins are important structural and functional molecules in the body.

2. The amino acids from proteins may be used for synthesis of new molecules or may be

burned for energy, depending on:

a. The presence of all necessary amino acids needed for a particular protein.

E. Vitamins mostly serve as coenzymes, many of which are not made by the body and must

be consumed (pp. 911–913; Table 24.2).

1. Vitamins A, D, E, and K are fat-soluble and are absorbed when bound to ingested

lipids.

II. Overview of Metabolic Reactions (pp. 913–917; Figs. 24.3–24.5)

A. Metabolic processes are either anabolic, in which larger molecules are synthesized from

smaller ones, or catabolic, in which large molecules are broken down to simpler ones

(pp. 913–914; Fig. 24.3).

1. In cellular respiration, food molecules are broken down in cells, with some of the

energy released used to power ATP synthesis, manufacture of the body’s primary

energy currency.

B. Oxidation-reduction reactions are coupled reactions that involve the transfer of electrons

from one molecule to another, resulting in a transfer of energy between molecules

(pp. 914–916).

1. In the body, oxidation-reduction reactions are enzyme-catalyzed reactions requiring

specific coenzymes that transfer the energy contained in food fuels to other molecules,

ultimately leading to the synthesis of ATP from ADP.

III. Metabolism of Major Nutrients (pp. 917–930; Figs. 24.6–24.16; Table 24.4)

A. Carbohydrate Metabolism (pp. 917–925; Figs. 24.6–24.13; Table 24.4)

1. Glucose enters the cell by facilitated diffusion and is phosphorylated to

glucose-6-phosphate, essentially trapping glucose within the cell.

2. Glucose enters glycolysis, an anaerobic process that occurs in the cytosol.

a. In phase 1 of glycolysis, sugar activation, glucose is phosphorylated in a series of

steps to fructose-6-phosphate to provide the activation energy for events that occur

later in the pathway.

3. The two pyruvic acid molecules can follow two distinct pathways, depending on the

availability of oxygen.

a. If adequate oxygen is present in the cell, glycolysis continues, and NADH delivers

4. In aerobic pathways, pyruvic acid is transported into the mitochondrion, where it

enters the Krebs cycle.

a. Pyruvic acid is first converted to acetyl CoA by removing a carbon, oxidizing the

5. The electron transport chain is the oxygen-requiring process of aerobic respiration

involving the pickup of hydrogens removed from food fuels during oxidation by O2,

resulting in the formation of water, a process called oxidative phosphorylation.

a. In the electron transport chain, hydrogens from NADH and FADH2 are shuttled

6. The net energy gain from one glucose molecule is 30 ATP.

7. Because the cell cannot store large amounts of ATP, other processes are used to

handle glucose in excess of what can be used in ATP synthetic pathways.

a. Glycogenesis is a process that forms glycogen from glucose when high cellular

ATP begins to inhibit glycolysis; this process occurs mostly in the liver and skeletal

muscle.

B. Lipid Metabolism (pp. 926–928; Figs. 24.14–24.15; Table 24.4)

1. Lipids are the body’s most concentrated source of energy, producing approximately

twice the energy of either carbohydrates or proteins.

2. Catabolism of triglycerides involves the splitting of the molecule into glycerol and

fatty acids: the glycerol portion is converted to glyceraldehyde phosphate, which

C. Protein Metabolism (pp. 928–930; Table 24.4)

1. Before amino acids can be oxidized for energy, they must have the amine group

removed, a process called deamination.

structural and functional proteins of the body.

IV. Metabolic States of the Body (pp. 930–935; Figs. 24.17–24.20; Table 24.5)

A. Catabolic-Anabolic Steady State of the Body (pp. 930–932; Fig. 24.17; Table 24.5)

1. There is a dynamic catabolic-anabolic state of the body as molecules are broken down

and rebuilt.

2. The body draws molecules to meet these needs from various nutrient pools: amino

acid, carbohydrate, and fat stores.

B. During the absorptive state, anabolism exceeds catabolism (pp. 931–933; Figs. 24.18–

24.19; Table 24.5).

1. All absorbed monosaccharides are made into glucose by the liver and released to the

blood or converted to glycogen or fat.

3. Insulin is the hormone that directs all events of the absorptive state:

a. Increases glucose uptake by body cells

b. Enhances glucose oxidation in tissue cells

f. Inhibits gluconeogenesis

C. In the postabsorptive state, net synthesis of fat, glycogen, and proteins ends, and the body

shifts to catabolism of these molecules (pp. 933–935; Figs. 24.20–24.21; Table 24.5).

2. If the body experiences prolonged fasting, it will enter glucose sparing, which is aimed

at conservation of blood glucose by promoting increased use of noncarbohydrate fuel

3. Hormonal and neural controls of the postabsorptive state:

a. Insulin-promoted processes are inhibited as insulin levels fall.

b. Declining blood glucose levels promote the release of glucagon, which targets the

liver, causing enhanced glycogenolysis, lipolysis, and gluconeogenesis, in order to

keep blood energy sources available to body cells.

V. The Metabolic Role of the Liver (pp. 935–938; Fig. 24.22; Table 24.6)

A. Cholesterol Metabolism and Regulation of Blood Cholesterol Levels (pp. 935–938; Fig.

24.22; Table 24.6)

2. Lipoprotein complexes vary in the percentage of lipid they contain, but all contain tri-

glycerides, phospholipids, and cholesterol, in addition to protein.

4. High levels of HDL are considered beneficial, as the cholesterol they contain is bound

for removal, but high levels of LDL are considered a risk, because the cholesterol they

contain may be laid down on vessel walls, forming plaques.

5. Blood levels of cholesterol are partly regulated through negative feedback, and a high

intake of cholesterol will somewhat inhibit cholesterol synthesis by the liver.

VI. Energy Balance (pp. 938–948; Figs. 24.23–24.26)

A. There is a balance between the body’s energy intake, defined as the energy produced

during food oxidation, and energy output, which includes energy lost as heat, used to do

work, or stored as fat or glycogen (pp. 938–939).

1. When energy intake and energy output are balanced, body weight remains stable, but

when they are not, weight is gained or lost.

C. Regulation of Food Intake (pp. 939–941; Fig. 24.23)

1. The hypothalamus produces several peptides controlling feeding behavior, which

ultimately reflect two sets of neurons: one set promoting hunger and the other set

promoting satiety.

3. Long-term regulation of food intake relies on the hormone leptin, secreted by adipose

cells.

4. Other factors that may affect food-seeking behaviors are changes in ambient tempera-

ture, stress, other psychological factors, infections, sleep deprivation, or composition

of gut bacteria.

D. Metabolic Rate and Heat Production (pp. 941–944)

1. The body’s rate of energy output is called the metabolic rate.

2. The basal metabolic rate reflects the amount of energy required for performance of

only the essential activities of the body and is expressed as kilocalories per square

meter of body surface area.

E. Regulation of Body Temperature (pp. 944–948; Figs. 24.24–24.26)

1. Body temperature averages 37°C and is usually maintained between 35.8–38.2°C.

2. Temperature homeostasis keeps body temperature at a value that is optimal for

enzymatic activity within the body.

from the lungs, oral mucosa, and the skin.

5. The hypothalamus contains the heat-loss and heat-promoting centers that aid in the

regulation of behavioral and physiological mechanisms to maintain normal body

temperature.

6. Heat-promoting mechanisms maintain or increase body core temperature and include

constriction of cutaneous blood vessels, shivering, increase in metabolic rate, and

increased release of thyroxine.

VII. Developmental Aspects of Nutrition and Metabolism (pp. 948–949)

A. Inadequate nutrition during pregnancy and in the first three years of life seriously

compromises brain growth and development, as well as muscle and bone development

(p. 948).

Cross References

Additional information on topics covered in Chapter 24 can be found in the chapters listed below.

1. Chapter 2: Chemical bonding; carbohydrates; lipids; proteins; water; ATP;

2. Chapter 3: Membrane transport; cytoplasm; mitochondria

3. Chapter 12: Hypothalamus

4. Chapter 13: Receptors

Lecture Hints

1. In order to fully understand the metabolic pathways, students should review the basic

concepts of chemistry in Chapter 2 and cellular structure in Chapter 3. Refer the class to

specific sections related to the lecture topic being discussed.

6. One of the most effective methods for presenting the biochemical pathways of

ATP synthesis is to start with a quick review of cell structure related to the process

(membranes, cytoplasm, mitochondria, etc.). Then give the overall outcome of each step

(glycolysis, Krebs cycle, electron transport), followed by a more detailed examination of

each step. It is essential that students see the “overall picture” in order to understand the

significance of the metabolic pathways.

10. Mention possible alternate terms for the Krebs cycle: citric acid cycle (citrate is the first

substrate in the cycle), tricarboxylic acid cycle (several intermediates have three carboxyl

groups).

11. A diagram of the chemiosmotic mechanism of ATP synthesis is very helpful in present-

ing electron transport. Construct a diagram of the phospholipid bilayer, fill in electron

carriers and the ATP synthase complex, and trace the pathway of electron flow. It is

helpful for the instructor to physically draw the diagram during class, especially if the

students are required to draw and/or analyze diagrams on the exam.

Activities/Demonstrations

1. Audiovisual materials are listed in the Multimedia in the Classroom and Lab section of

this Instructor Guide (p. 387).

2. Using the Dubois Body Surface Chart, students can make rough estimations of basal

metabolic rate by calculating respiratory rate and body surface area.

Critical Thinking/Discussion Topics

1. Discuss the need for a balanced diet.

3. Examine the differences between the fat- and water-soluble vitamins and why care

should be taken when using vitamins as a food supplement.

Library Research Topics

1. Investigate the pros and cons of vitamin and mineral supplements. What issues/concerns

exist surrounding dosages of high-potency supplements?

2. Study the effects of the inability to sweat.

List of Figures and Tables

All of the figures in the main text are available in JPEG format, PPT, and labeled & unlabeled

format on the Instructor Resource DVD. All of the figures and tables will also be available in

Transparency Acetate format. For more information, go to www.pearsonhighered.com/educator.

Figure 24.1 Two visual food guides.

Figure 24.2 Essential amino acids.

Figure 24.6 The three major phases of glycolysis.

Figure 24.7 Simplified version of the Krebs (citric acid) cycle.

Figure 24.8 Oxidative Phosphorylation.

Figure 24.9 Electronic energy gradient in the electron transport chain.

Figure 24.11 Structure and function of ATP synthase.

Figure 24.12 Energy yield during cellular respiration.

Figure 24.13 Glycogenesis and glycogenolysis.

Figure 24.14 Initial phase of lipid oxidation.

Figure 24.19 Insulin directs nearly all events of the absorptive state.

Figure 24.20 Major events and principal metabolic pathways of the postabsorptive

state.

Figure 24.21 Glucagon is a hyperglycemic hormone that stimulates a rise in blood

glucose levels.

Figure 24.25 Mechanisms of heat exchange.

Figure 24.26 Mechanisms of body temperature regulation.

Table 24.1 Summary of Carbohydrate, Lipid, and Protein Nutrients

Table 24.2 Vitamin Requirements of Humans

Answers to End-of-Chapter Questions

Multiple-Choice and Matching Question answers appear in Appendix H of the main text.

Short Answer Essay Questions

16. Cellular respiration is a group of reactions that break down (oxidize) glucose, fatty acids,

17. Glycolysis occurs in the cytoplasm of cells. It may be separated into three major events:

(1) sugar activation, (2) sugar cleavage, and (3) oxidation and ATP formation. During

sugar activation, glucose is phosphorylated, converted to fructose, and phosphorylated

again to yield fructose-1,6-biphosphate, consuming two molecules of ATP. These

reactions provide the activation energy for the later events of glycolysis. During sugar

18. Pyruvic acid is converted to acetyl CoA, which enters the Krebs cycle. For pyruvic acid

19. Glycogenesis is the process by which glucose molecules are combined in long chains to

form glycogen. Gluconeogenesis is the formation of new sugar from noncarbohydrate

molecules. Lipogenesis is the term for triglyceride synthesis.

a. Glycogenesis (and perhaps lipogenesis) is likely to occur after a carbohydrate-rich

21.

neutral fats glycerol

glucose

glyceraldehyde-3-phosphate

pyruvic acid

fatty acids

22. HDLs function to transport cholesterol from the peripheral tissues to the liver. LDLs

transport cholesterol to the peripheral tissues. (p. 936)

23. Factors influencing plasma cholesterol levels include diet (through intake of cholesterol

and/or saturated fatty acids), smoking, drinking, and stress. Sources of cholesterol in the

24. “Body energy balance” refers to the balance between energy intake and total energy

output. If energy intake exceeds energy output, weight is gained. Weight is lost if energy

output is greater than energy intake. (pp. 938–939)

25. Metabolic rate is increased with increased production of thyroxine. Eating increases

metabolic rate, an effect called chemical thermogenesis. A higher ratio of body surface

26. The body’s core includes organs within the skull and the thoracic and abdominal cavities.

27. Heat-promoting mechanisms to maintain or increase body temperature include vasocon-

striction in the shell, which inhibits heat loss via radiation; conduction and convection;

increase in metabolic rate due to epinephrine release; and shivering. Heat-loss mecha-

Critical Thinking and Clinical Application Questions

1. The number of ATP molecules resulting from the complete oxidation of a particular fatty

acid can be calculated easily by counting the number of carbon atoms in the fatty acid and

dividing by two to determine the number of acetyl CoA molecules produced. For our ex-

2. Hypothermia is abnormally depressed body temperature. It kills by dropping the body

temperature below the relatively narrow range in which biochemical reactions can take

3. With a diagnosis of high cholesterol and severe arteriosclerosis, he should avoid foods

containing saturated fatty acids and avoid eating eggs and large amounts of red meat.

He should substitute foods containing unsaturated fatty acids and add fish to his diet. He

should also stop smoking, cut down on his coffee, avoid stressful situations when possi-

ble, and increase his amount of aerobic exercise. (p. 938)

4. The chemiosmotic machinery concerns the operation of the electron transport chain and

5. Simon is exhibiting signs of vitamin C deficiency, otherwise known as scurvy. Although

he has rich sources of many nutrients on his island, his diet is lacking fruits and green

leafy vegetables as sources of vitamin C. (p. 912)