Chapter 24 Nutrition & Metabolism Lecture 12

1. Marieb’s Human Anatomy and Physiology Ninth Edition Marieb w Hoehn Chapter 24 Nutrition & Metabolism Lecture 12

2. Lecture Overview • Nutrition, nutrients, and metabolism • Macronutrients • Energy and energy requirements • Vitamins • Minerals • Nutritional abnormalities • Life-span changes

3. Nutrients Nutrients – chemical substances supplied by the environment required for survival (used for growth, repair, or maintenance of the body) • Macronutrients • carbohydrates • proteins • fats • Micronutrients • vitamins • minerals • Essential Nutrients • human cells cannot synthesize • include certain fatty acids, amino acids, vitamins

4. Review of General Metabolic Pathways Overall goal of catabolism is to generate a pool of 2- or 3-carbon molecules – the intermediates of metabolism – as well as energy (ATP) (6C) (3C) (2C) Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

5. Carbohydrates • Sources • sugars (simple) • starches (complex) - usually from plant sources • glycogen (complex) in meats • cellulose (complex) is indigestible fiber • Excesses lead to • obesity • dental caries • nutritional deficits • Deficiencies lead to • metabolic acidosis • weight loss Recommended (Dietary) Daily Allowance (RDA) is 125-175g *

6. Utilization of Carbohydrates Glucose is the body’s CHO energy source

7. Lipids • Sources • meats • eggs • milk • lard • plant oils • Excesses lead to • obesity • increased serum cholesterol • increased risk of heart disease • Deficiencies lead to • weight loss • skin lesions • hormonal imbalances RDA is 80-100g ( 30% of calories) ( 10% saturated fat) Fats generally take the longest to digest. Why?

8. Utilization of Lipids Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 How is fat absorbed from the digestive tract? Know these terms (see table of these terms later in this lecture) *

9. Energy Values of Food Calorie (kilocalorie, big calorie) – amount of heat needed to raise the temperature of 1 kg of water by 10 C Carbohydrates 4.1 Calories per gram Diet is 2000 Calories. What is the maximum number of grams of fat that should be taken in daily? Proteins 4.1 Calories per gram How many grams of fat are there in a Whopper with cheese and a small order of french fries? Lipids 9.5 Calories per gram Know this - you can round these off to the 4, 4, and 9)

10. Lipoprotein Traffic Figure From: Martini, Anatomy & Physiology, Prentice Hall, 2001 TG-rich Cholesterol-rich *Cholesterol can be manufactured from Acetyl-CoA Note the role of HDLs as scavengers of tissue/blood cholesterol.

11. Summary of Lipoproteins

12. Triglyceride Utilization of Lipids The liver uses fatty acids to synthesize a variety of lipids Linoleic, linolenic (plant oils)

13. Proteins • Sources • meats • cheeses • nuts • legumes Excesses can lead to obesity • Deficiencies lead to • extreme weight loss • muscle wasting • anemia • growth retardation Incomplete proteins – unable to maintain human tissues or support normal growth and development by themselves *RDA is 0.8g/kg body weight or 10% of diet (1 kg = 2.2 lbs) Essential amino acids (10; 8 in adult)– cannot be synthesized by the body (isoleucine, leucine, lysine, threonine, tryptophan, phenylalanine, valine, and methionine; arginine, histidine)

14. Utilization of Proteins • regulation of water balance • control of pH • formation of antibodies • build cell structures • enzymes • hormones • transport of oxygen

15. Utilization of Proteins for Energy Ammonia, NH3, or ammonium, NH4+ Highly toxic, even in small amounts Liver converts these to urea, a harmless water-soluble compound that can be excreted in the urine *

16. Nitrogen Balance Variety of compounds in the body contain nitrogen (N): amino acids, purines, pyrimidines, creatine, porphyrins. The body neither stores nor maintains reserves of N. There’s only about 1 kg of N in body at any one time. During starvation, N-containing compounds, like skeletal muscle, are conserved; CHO and fats are metabolized first (protein-sparing effect). Order of usage: CHO, fat, protein. • nitrogen balance - amount of nitrogen taken in is equal to amount excreted • negative nitrogen balance develops from starvation • positive nitrogen balance develops in growing children, pregnant women, or an athlete in training

17. Review of General Metabolic Pathways Overall goal of catabolism is to generate a pool of 2- or 3-carbon molecules – the intermediates of metabolism – as well as energy (ATP) Glycogenesis Lipo-genesis Glycogenolysis Lipolysis Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

18. Metabolism Hormones:Fed – InsulinFasted – Glucagon, Corticosteroids, Epi/NE -olysis  breakdown of -neo  new-genesis  creation of • Glycolysis – metabolism of glucose to pyruvate (Fed) • Gluconeogenesis – metabolism of pyruvate to glucose (CHO from non-CHO source) – (Fasted) • Glycogenesis – metabolism of glucose to glycogen (Fed) • Glycogenolysis – metabolism of glycogen to glucose (Fasted) • Lipolysis – breakdown of triglyceride into glycerol and fatty acids (Fasted) • Lipogenesis – creation of new triglyceride (fat) – (Fed)

19. The “Fed” (Absorptive) State Know this Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

20. The “Fasted” (Postabsorptive) State See Study guide for items you have to know Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

21. Energy Requirements • Basal metabolic rate (BMR) • rate at which body expends energy at rest (kcal/hr) • primarily reflects energy needed to support activities of organs • varies with gender, body size, body temperature, and endocrine function BMR is proportional to body weight Body’s basal metabolic rate (BMR) falls 10% during sleep and about 40% during prolonged starvation • Energy needed • to maintain BMR • to support resting muscular activity • to maintain body temperature • for growth in children and pregnant women BMR is profoundly affected by circulating thyroid hormone levels

22. Energy Balance • occurs when caloric intake in the form of food equals caloric output from BMR and muscular activities • positive energy balance leads to weight gain • negative energy balance leads to weight loss Body Mass Index (BMI)* = Wt (kg) / Height2 (m) * Source: World Health Organization

23. Overview of Vitamins • Organic substances required in small amounts that are not synthesized in adequate amounts to meet the body’s needs • Divided into two groups by solubility • Water-soluble – vitamins B (group) and C • Not generally stored • Excesses are excreted, e.g., in urine • Fat-soluble – vitamins A, D, E, and K • Stored in liver, adipose, other tissues • Excesses accumulate in tissues

24. The Fat-soluble Vitamins • Absorbed with fats in digestive tract • Function/Other sources • Vitamin A; structural component of retinal • Vitamin D • increases absorption of calcium and phosphorus from intestine • skin and UV light • Vitamin E • stabilizes internal cellular membranes • antioxidant • Vitamin K • Clotting (‘K’lotting) • bacteria in intestine and green, leafy vegetables *

25. Water-soluble Vitamins • Rapidly exchanged between fluid compartments of digestive tract and circulating blood • Excesses excreted in urine • Vitamins B12 and C are stored in larger quantities than other water-soluble vitamins • B vitamins [know these functions] • as a group, are coenzymes used to harvest energy • Vitamin B12 is important in hematopoiesis and maintenance of myelin sheath and epithelial cells • Vitamin C (ascorbic acid) [know these functions] • collagen production • Antioxidant / immune system booster •  absorption of iron

26. History of USDA’s Food Guidance Slide from: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt Food for Young Children 1992 1916 1940s 1970s 2005 1950s-1960s

27. New Food Pyramid (2005)

28. Food Pyramid From: http://www.mypyramid.gov/downloads/MyPyramid%20Peer%20to%20Peer.ppt

29. USDA’s ChooseMyPlate.gov From: http://www.choosemyplate.gov/images/MyPlateImages/JPG/myplate_blue.jpg USDA Dietary Guidance Web site: http://fnic.nal.usda.gov/dietary-guidance

30. Harvard School of Public Health Source: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/pyramid/

31. Malnutrition • poor nutrition • undernutrition – deficiency of essential nutrients • overnutrition – excess of nutrient intake • primary malnutrition – malnutrition from diet alone • secondary malnutrition – diet is sufficient but nutrients cannot be absorbed, e.g., insufficient bile

32. Starvation • person can survive 50-70 days without food (but vitamin deficiencies and their effects begin to appear after a week or two) • symptoms include metabolic acidosis, low blood pressure, slow pulse, chills, dry skin, hair loss, and poor immunity • Marasmus – lack of all nutrients • Kwashiorkor – protein starvation • Anorexia nervosa – eating disorder; self-starvation • Bulimia – eating disorder; bingeing and purging Body will adapt to starvation by using CHO first, then fats, and finally protein *

33. Regulation of Appetite Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 Also see Table 18.2 in Hole

34. I didn’t want to say anything, Dear, but… A mutation in the leptin gene in the ob/ob mouse (Right) leads to morbid obesity and provides an excellent experimental model.

35. Review

36. Review

37. Review

38. Review • Metabolism and fate of macronutrients • Carbohydrate • Broken down into monosaccharides • Metabolism, glycogen, fat, pentose sugars • Lipids • Saturated vs. unsaturated fats • Broken down into glycerol and fatty acids • Used for energy (or storage of energy) • Proteins • Complete vs. incomplete proteins • Broken down into amino acids • Structural components or energy

39. Review • Fat-soluble vitamins • Excesses are stored in tissues (liver, adipose) and not excreted; may become toxic • Includes vitamins A, D, E, and K • For exam see Table 18.8 on p. 708 and know the functions of the fat-soluble vitamins • Water-soluble vitamins • Excesses are excreted, e.g., urine • Vitamins B and C • For exam see Table 18.9 on p. 713 • B vitamins – know name/designation and know that the B vitamins are coenzymes that function in energy metabolism • Vitamin C – know its name and functions