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Chapter 25: Metabolism and Nutrition Read pages 951 to 987

Topic Outline and Objectives: Name___________________ A. Introduction to metabolism and metabolic reactions 1. Define a nutrient and list the functions of the six principle classes of nutrients. 2. Define metabolism and explain the role of ATP in anabolism and catabolism. 3. Describe the characteristics and importance of enzymes in metabolism. B. Carbohydrate metabolism C. Lipid metabolism D. Protein metabolism E. Minerals and Vitamins 4. Compare the sources, functions and importance of minerals and vitamins in metabolism. F. Metabolism during fasting and starvation G. Metabolism and heat 5. Define basal metabolic rate (BMR), and explain several factors that affect it. H. Nutrition 6. Describe how to select foods to maintain a healthy diet. I. Disorders 7. Define obesity, malnutrition, and digestive disorders. J. Clinical Applications A. Introduction to metabolism: A1. Complete this checkpoint about regulation of food intake. (See page 979 in your text)

a. The site within the brain that is the location of feeding and satiety centers is the ( medulla? hypothalamus? ). When the satiety center is active, an individual will feel ( hungry? satiated or full? ). b. The feeding center is constantly active except when it is inhibited by the ________________ center. Circle all of the answers that will keep the feeding center active and enhance the desire to eat.

↓ Glucose in blood ↓ Amino acids in blood ↓ Fats entering intestine (with related ↓ in CCK release) ↓ Environmental temperature ↓ Stretching of stomach

A2. List the six classes of nutrients on lines below. Circle those needed in greatest quantity. (See page 980 in your text)

_____________________ ______________________ __________________ _____________________ ______________________ __________________

A3. Complete this table comparing catabolism with anabolism. (Pages 951 – 953)

Process Definition Releases or Uses Energy

Examples

a. Catabolism

b. Anabolism

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A4. Explain why metabolism might be thought of as an “energy-balancing act” between anabolic and catabolic reactions. A5. In order for molecules to react with one another, they must have a certain amount of energy, known as _____________________ energy(the energy of motion). Answer the following question about this energy. a. One way to attain such energy is to heat the reacting molecules. Why would this be a problem in living systems? b. How can enzymes increase chemical reaction rates without requiring an increase in body temperature? c. Define a coenzyme (vitamins B niacin & riboflavin). How is it involved in energy transfer? A6. Consider catabolism (energy production) in this checkpoint. a. Organic nutrients such as glucose are rich in hydrogen; energy is contained within the C-H bonds. In catabolism, much of the energy in glucose is ultimately released and stored in the high- energy molecule named ____________________. Write the chemical formulas to show this overall catabolic conversion(oxidation) below:

_________________ → __________________ + ATP Glucose → Carbon dioxide + adenosine triphosphate

b. Note that the inorganic compound carbon dioxide is energy –( rich? poor? ) since it lacks C-H bonds. B. Carbohydrate metabolism - refer to energy pathways: (Pages 953 – 964) B1. Answer these questions about carbohydrate metabolism. a. The story of carbohydrate metabolism is really the story of __________________ metabolism, since this is the most common carbohydrate (and in fact the most common energy source) in the human diet. b. What other carbohydrates besides glucose are ingested? How are these converted to glucose? c. Just after a meal, the level of glucose in the blood ( increases? decreases? ). Cells use some of this glucose; by ( oxidizing? reducing? ) glucose, thus make cellular energy(ATP). d. List three mechanisms by which excess glucose is used or discarded by the body.

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B2. Describe the process of glycolysis in this exercise. a. Glucose is a ___________ -carbon molecule (which also has hydrogen and oxygen in it). During glycolysis each glucose molecule is converted to two, three-carbon molecules named _____________________. b. ( A lot? A little? ) energy is released from glucose during glycolysis. This process requires ( one? many? ) step(s) and ( does? does not? ) require oxygen. c. The fate of pyruvic acid depends on whether sufficient _______________ is available. If it is, pyruvic acid undergoes chemical change during glycolysis (glucose catabolism). These processes are ( aerobic? anaerobic? ), that is, they require oxygen. Where in the cell does this occur? d. If the respiratory rate cannot keep pace with glycolysis, insufficient oxygen is available to break down pyruvic acid. In the absence of sufficient oxygen, pyruvic acid is temporarily converted to ___________________. This is likely to occur during ( heavy? light? ) exercise. e. Give two examples of physical activity that could cause aerobic metabolism. B3. Write a chemical equation showing the total (aerobic) catabolism of glucose. B4. Most of the 38 ATP’s generated from the total oxidation of glucose derive from ( glycolysis? the Kreb’s cycle? ) B5. Complete the exercise about the reaction shown below. The hormones involved are shown.

Figure 25-1 a. You learned earlier that excess glucose may be stored as glycogen. In other words, glycogen consists of large branching chains of ____________________. Name the process of glycogen formation by label 1 in the chemical reaction above in Figure 25-1. b. Between meals, when glucose is needed, glycogen can be broken down again to release glucose. Label 2 above with the name of this process. c. Which of the two reactions in Figure 25-1 is anabolic? ______________________ d. Where is most (80 percent) of glycogen in the body stored?

Insulin Glucagon

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B6. Define gluconeogenesis and briefly discuss how it is related to other metabolic pathways, ie. lipids and proteins. a. Label the 2 pathways mentioned in B6, gluconeogenesis. Use red for lipids, and blue for proteins. (see “metabolic mill”) B7. The two molecules that appear to be most involved in the inter-conversions (links) among amino acids, fatty acids, and carbohydrates are pyruvic acid and _________________________. (Refer to the energy pathways) B8. Define dietary fiber. Why does it not supply any dietary energy, i.e. O Kcals? a. Give the RDA for fiber, and 3 benefits of a high fiber diet. B9. Respond to the question, “Are simple sugars bad for you?” Why or why not? C. Lipid metabolism: (Pages 964 – 967) C1. List six examples of structural or functional roles of fats in the body.

___________________ ___________________ ___________________

___________________ ___________________ ___________________ C2. Is the fat stored in your subcutaneous tissue “ the same fat” that was in that location two years ago? Explain a. Define lipogenesis and briefly discuss how it is related to other metabolic pathways, i.e. carbohydrates and proteins. b. Label the 2 pathways mentioned in C2 (a) lipogenesis. Use green for carbohydrates, and green for proteins (see metabolic mill) C3. Complete the exercise about fat catabolism. a. Fats must be broken into _____________________ and _____________________. Glycerol is converted into glyceraldehyde 3 phosphate and enters the glycolysis pathway.

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b. Recall that fatty acids are long chains of carbons, with attached hydrogens and a few oxygens. Two-carbon pieces are snipped-off of fatty acids by a process called beta-oxidation, which occurs in the liver. Some of these two-carbon pieces form acetyl coenzyme-A which then can enter the Kreb’s cycle reactions; in this way fats can release energy just as carbohydrates do. What molecule MUST be present in order for fats (fatty acids) to enter Kreb’s cycle? (see “metabolic mill”) c. The liver accumulates acetyl Co-A’s to form an increase of two types of ketone acids named: _____________________________ and ___________________________.

The presence of excessive amounts of these acids in the blood ( raises? lowers? ) blood pH.

Since these acids are called “keto” acids, the condition is known as _______________________ .

d. A slight alteration of acetoacetic acid (removal of CH3) forms acetone. Collectively, acetoacetic acid and acetone are known as keytone bodies. Formation of ketone bodies occurs

in the liver; the process is known as _______________-genesis.

e. Ketogenesis occurs when the cells are forced to burn fats incompletely. State two reasons why cells might carry out excessive fat catabolism leading to ketogenesis, and ultimately ketosis. f. Briefly explain why a diabetic might have “sweet breath”. Tell how this relates to fat metabolism. C4. Briefly describe how a diet that is excessive in carbohydrates or proteins can lead to formation of fat deposits (lipogenesis) in the body. C5. What are the three types of fats? How are they structurally different? Give a food example of each. a. Which type of fat is associated with coronary heart disease (CHD)? C6. Define essential fatty acid. List a “GOOD” food source.

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C7. Fats are the main fuel for muscles at rest and during light exercise. Explain why this is so. Hint: it has to do with oxygen. (Refer to the energy pathways) C8. Studies show that a person’s risk for coronary heart disease increases with low HDL blood levels. Explain why this is so. C9. Give two recommendations from the American Heart Association for preventing CHD. D. Protein Metabolism: (Pages 967 – 969) D1. Which of the three major nutrients (carbohydrates, lipids, and proteins) fulfills each function? a. Most direct source of energy; stored in body least: ___________________ b. Second as source of energy; stored in body most: ___________________ c. Used least for energy; used most for body-building: ___________________ D2. Contrast the caloric values of the three major food types. Refer to your pie chart! a. Carbohydrates and proteins each produce _______Kcal/g or (since a pound contains 448 g) _______ Kcal/lb. b. Fats produce ________ Kcal/g or ________ Kcal/ lb. D3. Throughout your study of systems of the body so far, you have learned about a variety of roles of proteins. In one or two words each, list at least six functions of proteins in the body. Include some structural and some regulatory roles.

_____________________________ _____________________________

_____________________________ _____________________________

_____________________________ _____________________________ D4. Refer to Figure 25-2 and describe the uses of protein. Two resources of proteins are shown: (a)__________________ and (b)____________________. Amino acids from these sources may undergo a process known as (c) _____________________ to form new body proteins. If other energy sources are used up, amino acids may undergo catabolism. The first step is (d)________________, in which an amino group (NH2) is removed and converted (in the liver) to (e) ________________(NH3), a component of (f)______________, which exists in urine. The remaining portion of amino acid may enter (g) glycolysis or ____________________ pathways at a number of points. In this way, the remaining portion of the amino acid molecule can lead to the formation of (h)________________________.

(give three products here)

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Figure 25-2

D5. Contrast essential amino acids and nonessential amino acids. D6. What is the recommended amount of protein intake per day, and type of exercise in order for a person to increase muscle mass? a. What might be 3 situations where a person may need more protein than the RDA? E. Minerals and Vitamins: (Pages 982 – 985) E1. Define minerals. a. Minerals make up about ______ percent of body weight and are concentrated in the ___________________.

Kreb’s

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E2. Study Table 25-5, on page 983 in your text. Then check your understanding of minerals by doing this matching exercise. Some may be used more than once!

Ca. Calcium Fe. Iron Na. Sodium

Cl. Chlorine I. Iodine P. Phosphorous Co. Cobalt K. Potassium S. Sulfur

F. Fluorine _____ a. Main anion(-) in extracellular fluid, part of HCI in stomach; component of table salt.

_____ g. Constituent of vitamin B12, so necessary for red blood cell formation.

_____ b. Involved in generation of nerve impulse; a major cation(+) in the ECF.

_____ h. Important component of amino acids, hair, nails, vitamins, and hormones.

_____ c. Most abundant cation(+) in the body, found mostly in bones and teeth; necessary for normal muscle contraction and for blood clotting.

_____ i. Deficiencies can cause osteoporosis, osteomalacia in adults, and rickets in children.

_____ d. Important component of hemoglobin and cytochromes (electron carriers). Deficiencies lead to anemia.

_____ j. Found mostly in bones and teeth; important in buffer system and in ATP processes; component of DNA and RNA.

_____ e. Main cation inside of cells; used in nerve transmission.

_____ k. Processed food supply the greatest amount. Can cause hypertension in excess.

_____ f. Essential component of thyroxin. Deficiencies lead to “goiter”

_____ l. Improves tooth structure. May help prevent tooth decay.

E3. Circle the correct answer. The primary function of vitamins is: A. Synthesis of body structures B. Regulation of body activities E4. Vitamins are ( organic? inorganic? ). Most vitamins ( can? cannot? ) be synthesized in the body. In general, what are the functions of vitamins? E5. Contrast the two principal groups of vitamins, and list the main vitamins in each group. a. Fat-soluble____________________ (Fat-soluble means?) b. Water-soluble _____________________ (Water-soluble means?) E6. Defend or dispute this statement: “Most people who eat a balanced diet do need to take vitamins or mineral supplements.” E7. The initials RDA found on vitamins and minerals refer to

R_____________________ D_____________________ A______________________

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E8. Study Table 25-6, on page 984 in your text. Select the vitamin that fits each description below.

A B1 B2 B12 C D E K _____ a. This serves as a coenzyme that is essential for blood clotting, so it is called the anti-hemorrhagic vitamin; synthesized by intestinal bacteria (e. coli).

_____ e. Formed from carotene, it is necessary for normal bones and teeth; it prevents night blindness.

_____ b. Its formation depends upon sunlight on skin and also on kidney and liver activation\; necessary for calcium absorption.

_____ f. This substance is also called ascorbic acid; deficiency causes anemia, poor wound healing, and scurvy.

_____ c. Riboflavin is another name for it; a component of FAD; necessary for normal integrity of skin, mucosa, and eye.

_____ g. This coenzyme, the only B vitamin not found in vegetables, is necessary for normal erythropoiesis; absorption from GI tract depends on intrinsic factor.

_____ d. This vitamin acts as an important coenzyme in carbohydrate metabolism; deficiency leads to beriberi.

_____ h. Also known as tocopherol, it is necessary for normal red blood cell membranes. May help prevent scarring.

F. Metabolism during fasting and starvation: (Page 975) F1. A clinical correlation: Describe the metabolic changes during fasting or starvation. a. Contrast these terms: fasting/starving b. State the major factor that determines the life span possible without food. c. Explain what accounts for the ”wasting” appearance of people who are starving to death. d. Explain why extremely high blood levels of ketone bodies (which provide up to 2/3 of the energy to the brain after many weeks of starvation) may be dangerous and even lethal for example, leading to coma and death. G. Metabolism and Heat: (Page 975- 980) G1. Contrast calorie and kilocalorie a. If you ingest, digest, absorb, and metabolize a slice of bread, the energy released from the bread equals about 80-100 ( cal? Kcal? ). G2. Answer these questions about catabolism. a. Catabolism of foods ( uses? releases? ) energy. Most of the heat produced by the body comes from catabolism by ( oxidation? reduction? ) of nutrients.

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G3. Define basal metabolic rate (BMR). What is your BMR? a. List four conditions that are necessary in order for the body to be in a basal state (BMR).

_____________________________ __________________________ _____________________________ __________________________

G4. Calculate a typical BMR in this exercise. a. BMR may be determined by measuring the amount of ___________ consumed within a period of time, since oxygen is necessary for the metabolism of foods. Normally, for each liter of oxygen consumed, the body metabolizes enough food to release about ________ Kcal/kg/hr. b. Suppose you consume 15 liters of oxygen in an hour. Your body would release _______ Kcal of heat in that hour. c. A BMR of 20% below the standard value is likely to be due to ( hyper? hypo? )-thyroidism. G5. Discuss factors that affect how rapidly your body catabolizes, that is, your metabolic rate. Include: Exercise, nervous system, hormones, body temperature, age, and pregnanacy. H. Nutrition: (pages 980 – 985) H1. List three primary functions of nutrients. H2. Fill in the number of calories needed each day by typical persons in each category. 1600 calories/day 2200 calories/day 2200 calories/day 2800+ calories/day _____ a. Active women, teen girls, and most men. _____ b. Active men and teen boys

_____ c. Elderly adults _____ d. Children

H3. Fill in the percentage of calories needed each day in each category of nutrients. Use your pie chart. a. Carbohydrates: _________ % b. Proteins: _________ % c. Fats: no more than _________ % with no more than _________ % of total calories in the form of saturated fats.

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H4. Critical thinking. Keep in mind that carbohydrates and proteins each provide about 4 kcal/gram and fats provide 9 kcal/gram. Considering the information in H3, determine the number of grams of each of the three major nutrient groups appropriate for a healthy diet of 2000 kcal/day. One is done for you. Use your pie chart for energy conversions. a. Proteins: 2000 kcal X (0.12) = 240 kcal/day. So, at 4 kcal/gram = 60 grams/day b. Carbohydrates: c. Fats: H5. What is the recommendation for weight loss. Give the energy and activity requirements. H6. Using the Food Plate below (or go to choosemyplate.gov), identify the number of servings suggested per day for each food group in the plate. Use the corresponding numbers.

1) 3 cups/day 2) 2.5-3 cups/day 3) 1.5-2 cups/day 4) 5–6 oz./day 5) 3–4 oz./day 6) 5–6 tsp/day

_____ a. Bread, cereal, rice, pasta (whole grains) _____ b. Vegetables _____ c. Fruits

_____ d. Meat, fish, poultry, beans, eggs, nuts (lean protein) _____ e. Milk, yogurt, and cheeses (fat free dairy) _____ f. Fats, oils, and sweets

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H7. Write seven guidelines for healthy eating. (see tips on web page) I. Disorders: (pages 986 – 987) I1. Circle the correct answer to complete each statement. a. Obesity is defined as a body weight ________ percent above desirable weight.

10 – 12 > 20 100

b. State three causes of obesity. c. A more popular surgery in which the upper jejunum (small intestine) is stapled to the lower small intestine (ileum) is known as: Circle your answer.

Intestinal bypass Gastric balloon

d. Protein deficiency despite adequate caloric intake is a description of: Circle your answer.

Marasmus Kwashiorkor I2. Match the terms with the descriptions below. See chapter 24, pages 942 – 944 for extra help!

A. Anorexia nervosa D. Diarrhea B. Bulimia F. Flatus Con. Constipation Co. Spastic Colitis or irritable colon Htb. Heartburn Colo. Colostomy

_____ a. Incision of the colon, creating an artificial anus.

_____ e. Infrequent or difficult defecation. Usually associated with low fiber diets.

_____ b. Inflammation of the colon. A nervous bowel.

_____ f. Excess air (gas) in the stomach or intestines; usually expelled through anus.

_____ c. Burning sensation in region of the esophagus and stomach; probably due to gastric contents in lower esophagus.

_____ g. Binge-purge syndrome. Usually binge on “junk food”.

_____ d. Frequent defecation of liquid feces. Can cause an electrolyte imbalance.

_____ h. Loss of appetite and self-imposed starvation.

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J. Clinical Applications for Chapter 25: Please respond in complete, coherent thought! 1. Define amino acid pool and explain how the pool is maintained even though we excrete amino acids daily. 2. Hyper-vitaminosis may have serious consequences. Which vitamin group, water or fat soluble, is most likely to be involved in such cases and why?

3. What is obesity, and what health problems accompany or follow its onset? 4. Explain why many elderly are obese, even though they actually eat very little? 5. Define nitrogen balance. List three factors that might lead to negative nitrogen balance and three that

might result in positive nitrogen balance. 6. Hank, a 17-year-old high school student, suffered a heart attack during a recreational swim. An autopsy revealed that he had atherosclerosis and that his death had been caused by coronary artery disease. What might have been the cause of this disease that usually strikes a person much older than Hank? 7. A young athlete is admitted to the hospital with diarrhea, vomiting, bone and joint pain, hyperglycemia and tingling sensations. What is the problem? 8. Mary Maroon comes to the clinic to get information on a vegetarian diet. What problems may arise when people make decisions on what to eat for a vegetarian diet? What combination of vegetable foods will provide Mary with all the essential amino acids? 9. A group of new parents is meeting to learn about the good nutrition for their children. The topic is “empty calories.” What does the term mean and what are some foods with the empty calories? 10. Zena, a teenager, has gone to the sports clinic for the past 2 years to have her fat content checked. This year, her percent body fat is up and tissue protein has not increased. Questioning reveals that Zena has been on crash diets four times since the last checkup, only to regain the weight (and more) each time. She also admits sheepishly that she “detests” exercise. How does cyclic dieting, accompanied by lack of exercise, cause an increase in fat (adipose) and a decrease in protein stores (lean body mass)?

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Sample Nutritional Calculations: 1. What is 6% of 45? 2. What is 32% of 8? 3. What percent of 16 is 6? 4. What percent of 99 is 3? 5. Joe ate 15% of the adult (RDA) for vitamin C at lunch. How many milligrams did he eat? (Hint: the RDA = 60 mg) 6. Joe ate 200 grams of carbos, 100 grams of fat, and 70 grams of protein yesterday. A. Calculate the kcal break down for carbos, proteins, fats B. Calculate the total intake of kcals. C. Give the % kcal intake for each group D. Does Joe meet the RDA for adults? (Compare the 3 nutrients to RDA chart). Remember: * Carbos = 4 kcal/gram * Protein = 4 kcal/gram * Fat = 9 kcal/gram 7. If a person needs 2200 kcal/day, calculate the actual number of kcal provided by: A. 55% from total kcals are carbos B. 15% from protein C. 30% from lipid