Download Lecture Suggestions and Guidelines

CHAPTER 18
NUTRITION AND METABOLISM
LEARNING OBJECTIVE 1: Define nutrition, nutrients, and essential nutrients.
Lecture Suggestions and Guidelines
1. Discuss several factors, which influence what we choose to eat.
2. Define nutrition in terms of its interaction with physiological, psychological,
social, cultural, economic, and technological factors.
3. Describe macronutrients and micronutrients.
4. Define metabolism.
5. Discuss essential nutrients as those, which must be provided in the diet. Give
examples of essential nutrients.
Application Question(s)
1. Ask students to provide specific examples of how nutrients help meet the body’s
energy requirements, the need to maintain structure, and the need to regulate body
functions.
Answer: Examples might include carbohydrates in the form of blood glucose
being used for cellular energy; minerals in the form of calcium and phosphorus
help maintain tooth structure; proteins in the form of transferring help regulate the
transport of iron.
Critical Thinking Issue(s)
1. Discuss the nutritional health of the nation. Students should consult various
sources to accumulate their facts. What is the students’ overall assessment of
nutritional health in the United States?
Answer: Responses should include discussion of food availability, consumption,
food composition and labeling, attitudes, behavior, and knowledge about foodrelated issues.
LEARNING OBJECTIVE 2: List the major sources of carbohydrates, lipids, and
proteins.
Lecture Suggestions and Guidelines
1. Describe the major sources of carbohydrates. Include a discussion of starch,
glycogen, disaccharides, monosaccharides, and cellulose.
2. Discuss the major sources of lipids, including fats, phospholipids, and cholesterol.
The most common dietary lipids are triglycerides obtained from plants and animal
products.
3. Lecture on the major sources of proteins. Discuss essential amino acids.
Distinguish between complete and incomplete proteins.
Application Question(s)
1. Apply the information discussed in this learning objective to a discussion of the
six major types of vegetarian diets. Can a person be nutritionally healthy while
staying on one of these diets?
Answer: Responses will vary. Benefits and pitfalls exist for vegetarian diets. On
one hand, vegetarian diets may reduce disease risks, are more economical, etc.
Pitfalls may include a concern about certain vitamin and mineral deficiencies.
Critical Thinking Issue(s)
1. Discuss the potential causes of obesity.
Answer: Obesity usually equates to 15-20% or more over a person’s “ideal
weight”. It is due to an abnormal accumulation of adipose tissue. The causes are
many and varied; obesity could be caused by poorly matched caloric intake and
physical activity, a genetic component, a behavioral component, cultural and
environmental factors, or a combination of the above. Treatment may involve
diets, exercise programs, medications, and/or behavioral modification.
LEARNING OBJECTIVE 3: Describe how cells utilize carbohydrates, lipids, and
amino acids.
Lecture Suggestions and Guidelines
1. Discuss the absorption of carbohydrates as monosaccharides.
2. Describe the liver’s role in converting fructose and galactose to glucose.
3. Define oxidation.
4. Explain how excess glucose is stored as glycogen or converted to fat.
5. Describe the role of the liver and adipose tissue in controlling triglyceride
metabolism.
6. Briefly introduce the structure of fatty acids and how the liver may alter their
structures.
7. Describe linoleic acid.
8. Discuss the regulation of cholesterol levels by the liver.
9. Distinguish between essential and nonessential amino acids.
10. Identify the eight essential amino acids.
11. Discuss several uses of polymers of amino acids (proteins), including enzymes,
clotting factors, keratin, elastin, collagen, plasma proteins that regulate water
balance, actin, myosin, hormones, and antibodies. Give examples.
12. Distinguish between complete and incomplete proteins.
Application Question(s)
1. What recommendations would students give in terms of changes in carbohydrate
intake in a typical North American diet?
Answer: Responses will vary.
2. Which lipids are synthesized from fatty acids processed in the liver?
Answer: Triglycerides, lipoproteins, cholesterol, phospholipids, and some fatty
acids.
3. Ask the students to name twenty-one amino acids. Which eight are considered to
be essential? Which two additional amino acids are essential in growing children?
Answer: The eight essential amino acids are isoleucine, leucine, lysine,
methionine, phenylalanine, threonine, tryptophan, and valine. The two additional
essential amino acids in growing children are arginine and histidine.
Critical Thinking Issue(s)
1. Trace the pathways which starch, sucrose, maltose, and lactose take upon being
digested.
Answer: All are converted to monosaccharides. Starch is converted to glucose,
sucrose to glucose and fructose, maltose to glucose, and lactose to glucose and
galactose. The monosaccharides are then utilized in a variety of processes,
including respiration, glycogenesis, and lipogenesis.
2. Compare/contrast the roles of chylomicrons, VLDLs, LDLs, and HDLs.
Answer: Chylomicrons transport lipids from the intestines and carry triglycerides
to the body cells, very-low-density lipoproteins transport lipids from the liver and
carry triglycerides to the body cells, low-density lipoproteins transport cholesterol
to body cells, and high-density lipoproteins transport cholesterol away from body
cells (and are thus called “good” lipoproteins).
3. Describe the process by which deaminated amino acids may be used to produce
cellular energy.
Answer: Responses should include a discussion of glycolysis in the cell
cytoplasm, the formation of acetyl-CoA in the mitochondria, the citric acid cycle
in the mitochondria, and the electron transport chain mechanism in the
mitochondrial membrane.
LEARNING OBJECTIVE 4: Define nitrogen balance.
Lecture Suggestions and Guidelines
1. Lecture on the concept that the amount of nitrogen taken in is equal to the amount
excreted.
2. Distinguish between a negative and positive nitrogen balance. Give examples of
people who would fall into each category.
Application Question(s)
1. Ask students to give specific examples of cases in which a positive nitrogen
balance may occur; A negative nitrogen balance.
Answer: The textbook provides the following examples of a positive nitrogen
balance: a growing child, a pregnant woman, or an athlete in training. A negative
nitrogen balance may be the result of starvation. Ask students for additional
examples.
Critical Thinking Issue(s)
1. Given the information provided in the above application question, under what
circumstances might an athlete in training actually exhibit a negative nitrogen
balance?
Answer: It is possible for an athlete in training to exhibit a negative nitrogen
balance if he/she were participating in a low protein diet while attempting to lose
weight. A low energy, low protein diet may result in a negative nitrogen balance
because the athlete’s body is breaking down protein to meet energy needs,
resulting in excess excretion of nitrogen in the urine.
LEARNING OBJECTIVE 5: Explain how the energy values of foods are determined.
Lecture Suggestions and Guidelines
1. Define calories and kilocalories.
2. Describe a bomb calorimeter.
3. Discuss the caloric values derived from the oxidation of one gram of
carbohydrate, one gram of protein, and one gram of fat.
Application Question(s)
1. Ask students to prepare a list of twenty activities. Assign the number of calories
used per hour to each activity. Of all activities investigated, which used the
greatest number of calories? Least?
Answer: Answers will vary.
Critical Thinking Issue(s)
1. Demonstrate the use of a bomb calorimeter to the class. Each student could
submit one food source for experimentation. Rank the foods based on amount of
heat released during combustion.
Answer: Responses will vary.
LEARNING OBJECTIVE 6: Explain the factors that affect an individual’s energy
requirements.
Lecture Suggestions and Guidelines
1. Discuss basal metabolic rate (BMR).
2. Emphasize the concept that the amount of energy required varies from one
individual to another.
3. Discuss factors that influence energy requirements.
Application Question(s)
1. What factors determine basal metabolic rate?
Answer: Surface area of the individual, sex, thyroxine production, age, and
emotions have all been shown to have an effect on BMR.
Critical Thinking Issue(s)
1. Compare and contrast the terms basal metabolic rate and total metabolic rate.
Answer: BMR is the amount of heat produced when the body is at rest. TMR is
the total amount of calories the body needs to support activity such as work by the
skeletal muscles. Homeostasis is maintained when TMR is equal to the total
calories consumed.
LEARNING OBJECTIVE 7: Define energy balance.
Lecture Suggestions and Guidelines
1. Define the term energy balance.
2. Distinguish between positive and negative energy balance.
3. Describe the effects of energy balance upon body weight.
Application Question(s)
1. What is the difference between hunger and appetite?
Answer: Hunger is the physiological drive to consume food, stimulated by the
body’s internal signals. Appetite relates to a drive to eat, not related to hunger.
For instance, the desire to eat dessert after a big meal (as a form of reward
system) is based on appetite, not hunger.
Critical Thinking Issue(s)
1. Ask students to address the effects of emotions upon appetite.
Answer: Responses will vary. An emotion which causes one individual to eat, for
example, stress, may cause another individual to “lose” his appetite.
LEARNING OBJECTIVE 8: Explain what is meant by desirable weight.
Lecture Suggestions and Guidelines
1. Discuss what is meant by desirable weight.
2. Define overweight and obese. Compare the terms.
3. Discuss cases in which being slightly overweight or underweight may be
desirable.
Application Question(s)
1. What is each student’s desirable weight? Obtain an obsolete chart of weight
standards based on average weights and heights. How many students are within
the acceptable range of desirable weight?
Answer: The results may be surprising when compared to the numbers of
students who fall into the desirable weight range based on more recent charts.
More recent charts are based on people who live the longest, and are more lenient
than prior standards.
Critical Thinking Issue(s)
1. Ask students to devise a list of instances in which weight gain may be desirable;
undesirable. Compose another list, which summarizes when weight loss may be
desirable; undesirable. Do all students agree?
Answer: Responses will vary.
LEARNING OBJECTIVE 9: List the fat-soluble and water-soluble vitamins and
summarize the general functions of each vitamin.
Lecture Suggestions and Guidelines
1. Lecture on the general characteristics of fat-soluble vitamins and water-soluble
vitamins. Compare and contrast their characteristics.
2. Discuss the structures, functions, and locations of the fat-soluble vitamins,
including vitamins A, D, E, and K.
3. Discuss the structures, functions, and locations of the water-soluble vitamins,
including eight forms of the vitamin B complex and vitamin C (ascorbic acid).
Application Question(s)
1. Prepare a set of index cards, each of which features the name of a fat-soluble or
water-soluble vitamin on one side, and the characteristics, functions, sources,
conditions associated with excesses, and conditions associated with deficiencies
on the other side.
Answer: The students will have a set of thirteen index cards when finished, which
they can use for future reference.
Critical Thinking Issue(s)
1. Ask students to prepare a short report on a disease of malnutrition based on
deficiency of a major vitamin. Topics may include beriberi, pellagra, scurvy,
osteomalacia, etc.
Answer: The report should include a definition of the disease, cause, signs and
symptoms, course, outcome, and prognosis.
LEARNING OBJECTIVE 10: Distinguish between a vitamin and a mineral.
Lecture Suggestions and Guidelines
1. Reiterate the concept that vitamins are organic compounds, minerals are inorganic
compounds.
2. Discuss the concept that solubility determines how vitamins are absorbed,
transported, excreted, and stored in the body. Vitamins do not directly provide
energy.
3. Describe the occurrence of minerals. Approximately 75% of the minerals are
found in bones and teeth.
4. Explain that minerals in the ionized form are physiologically active.
Application Question(s)
1. Compare the chemical structures and characteristics of a selection of vitamins and
minerals.
Answer: Vitamins are carbon-containing compounds and tend to be larger, more
complex molecules. Minerals are inorganic compounds and tend to be
physiologically active in the ionized state. Illustrations which compare structures
would be beneficial, as would ball-and-stick models of the vitamins.
Critical Thinking Issue(s)
1. Is more vitamin C always better? Does vitamin C really prevent common cold
symptoms? What are the implications of hypervitaminosis with vitamin C?
Answer: Studies have shown that the human body will attempt to excrete excess
vitamin C, which it cannot use. Debate still exists as to the preventive effects of
vitamin C against colds. A dietary excess of vitamin C exacerbates gout and
kidney stone formation.
LEARNING OBJECTIVE 11: List the major minerals and trace elements and
summarize the general functions of each.
Lecture Suggestions and Guidelines
1. Discuss the major minerals found in the human body; give the name, functions,
locations, consequences of dietary excess, and consequences of dietary deficiency
for each, including calcium, phosphorus, potassium, sulfur, sodium, chlorine, and
magnesium.
2. Discuss the trace elements found in the human body; give the name, functions,
locations, consequences of dietary excess, and consequences of dietary deficiency
for each, including iron, manganese, copper, iodine, cobalt, zinc, fluorine,
selenium, and chromium.
Application Question(s)
1. Ask students to prepare index cards featuring the name of a major mineral or trace
element on one side, and the distribution, functions, sources, conditions associated
with excesses, and conditions associated with deficiencies on the other side.
Answer: When completed, the students will have a set of no fewer than sixteen
index cards, which they may use for future reference.
Critical Thinking Issue(s)
1. What kinds of actions can students take to reduce their sodium intake?
Answer: Responses will probably include reducing salt intake gradually, reading
food labels more carefully, reduce snacking, add little or no salt when cooking,
order more carefully at restaurants, limit the use of a salt shaker, limit intake of
processed cheeses, etc.
LEARNING OBJECTIVE 12: Describe an adequate diet.
Lecture Suggestions and Guidelines
1. Describe the food pyramid system.
2. Discuss the information available on food labels and interpret its meaning.
3. Define adequate diet.
4. Discuss devices, which are available to help consumers make healthy food
choices.
Application Question(s)
1. Why is the food guide pyramid shaped like a pyramid?
Answer: The pyramidal shape is significant because it emphasizes that foods at
the base of the pyramid should be more abundant (more servings) than foods at
the narrow peak. Bread, cereal, rice and pasta are at the base of the pyramid,
comprising 6–11 servings per day. Fruits and vegetables are at the next highest
level at 3–5 servings, followed by milk, yogurt, cheese, meat, poultry, fish, dry
beans, eggs, and nuts at 2–3 servings, and finally fats, oils, and sweets at the
pyramid’s apex, which should be used sparingly.
Critical Thinking Issue(s)
1. Ask students to bring in labels from some of their favorite foods. Analyze the
nutrition facts stated on the label regarding the container’s contents.
Answer: Responses will vary.
LEARNING OBJECTIVE 13: Distinguish between primary and secondary
malnutrition.
Lecture Suggestions and Guidelines
1. Define malnutrition. Emphasize the fact that a person may eat too much, be
overweight, or obese, and still be malnourished.
2. Explain the difference between primary and secondary malnutrition.
3. Discuss the signs and symptoms of starvation.
4. Describe several nutritional disorders.
Application Question(s)
1. What health claims are advertisers making regarding their products? Are these
claims supported by the Food and Drug Administration? Collect some examples
from magazines, newspapers, and television commercials to discuss in class.
Critical Thinking Issue(s)
1. Compare and contrast anorexia nervosa and bulimia.
Answer: Anorexia nervosa is self-starvation. Its manifestations include
amenorrhea, decreased blood pressure and heart rate, anemia, dehydration,
immunosuppression, and weight loss. An anorexic views himself as overweight,
even during starvation. Bulimia is a binge-purge syndrome. The manifestations
include tooth decay, sore throat, inflammation of the salivary glands, dehydration,
electrolyte imbalance, heart irregularities, and stomach rupture. Both anorexia
nervosa and bulimia patients are treated for malnutrition and receive
psychological counseling.
LEARNING OBJECTIVE 14: List factors that may lead to inadequate nutrition later in
life.
Lecture Suggestions and Guidelines
1. Describe the effects of medical condition and socioeconomic circumstances that
may affect nutrition of the elderly.
2. Discuss the effects of aging on basal metabolic rate.
3. Identify the changes in energy balance and its effects upon activity levels later in
life.
Application Question(s)
1. Ask students to develop a food guide pyramid that would be appropriate for the
elderly. How does it differ from a similar pyramid for a teenager?
Answer: Responses will vary.
Critical Thinking Issue(s)
1. Compare and contrast the lasting effects of starvation with those of overeating.
Answer: Responses should include a discussion of the fact that both cases
represent a form of malnutrition.
RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Beriberi—A condition resulting from a thiamin (vitamin B1) deficiency. Its
manifestations include demyelination of nerve fibers, leading to extraneous
perception of stimuli, weakening of appendages, confusion, and paralysis of eye
muscles.
2. Scurvy—Results from an ascorbic acid (vitamin C) deficiency. Manifestations
include a separation of cells in epithelial tissue, and an insufficient production of
collagen. The gums may be severely affected. Scurvy can usually be prevented
with a proper diet, including citrus fruits and fresh vegetables.
3. Bulimia—A psycho-neurotic disorder in which the patient binges and purges.
This condition may cause tooth decay, sore throat, inflammation of salivary
glands, dehydration, electrolyte imbalance, heart irregularities, or stomach
rupture. Treatment usually involves medications and psychological counseling.
SUGGESTIONS FOR ADDITIONAL READING
Bower, Bruce. June 17, 2000. Neandertals’ diet put meat in their bones. Science News,
vol. 157, no. 25, pg. 389.
Elmer-Dewitt, Phillip. January 16, 1995. Fat Times. Time. Why are so many of us
overweight? For most of us, the environment plays a greater role than heredity.
Farley, Dixie. March 1992. Eating disorders require medical attention. FDA Consumer.
Anorexia nervosa and bulimia are serious, life-threatening disorders.
Foulke, Judith E. April 1992. Good news about good nutrition. FDA Consumer. You can
eat in a way that promotes good health.
Kurtzweil, Paula. January/February 1993. Nutrition information available for raw fruits,
vegetables, fish. FDA Consumer. We should eat more fruits, veggies, and fish.
Kurtzweil, Paula. March 1995. Labeling rules for young children’s food. FDA Consumer.
Children under age four years have different nutritional requirements.
Rink, Timothy J. December 1, 1994. In search of a satiety factor. Nature, vol. 372. Genes
control the biochemical pathways that control energy utilization—and therefore body
weight.
Ronald, Pamela C. November, 1997. Making Rice Disease-Resistant. Scientific
American.
Saltos, Etta. June 1993. The food pyramid-food label connection. FDA Consumer. Tips
on how to implement the food pyramid and read new food labels.
Spiller, Gene. 1003. The superpyramid eating program. New York: Times Books. Using
the food pyramid plan.
Wagner, Bill. November 1993. Surprising sources for new foods. FDA Consumer. Eating
a variety of foods helps ensure that you meet nutritional needs.