Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Memmler’s The Human Body in Health and Disease 11 th edition Chapter 20 Metabolism, Nutrition and Body Temperature

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins MetabolismMetabolism Two categories Catabolism –Breakdown complex compounds into simpler compounds Anabolism –Building simple compounds into needed substances

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Cellular Respiration Energy released from nutrients in a series of reactions Early studies done with glucose as starting compound

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Cellular respiration. This diagram shows the catabolism of glucose without oxygen (anaerobic) and with oxygen (aerobic). (C = carbon atoms in one molecule of a substance.) In cellular respiration, glucose first yields two molecules of pyruvic acid, which will convert to lactic acid under anaerobic conditions, as during intense exercise. (Lactic acid must eventually be converted back to pyruvic acid.) Typically, however, pyruvic acid is broken down aerobically (using oxygen) to CO2 and H2O (aerobically). Zooming In: What does pyruvic acid produce in cellular respiration under anaerobic conditions? Under aerobic conditions?

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Anaerobic Phase Occurs in cytoplasm Yields 2 ATP molecules per glucose molecule Product is pyruvic acid

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Aerobic Phase Occurs in mitochondria Yields ATP molecules per glucose molecule Product is carbon dioxide and water

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Metabolic Rate Rate at which energy is released from nutrients in cells Decreases with age Measured in kilocalories (kcal)

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Use of Nutrients for Energy Glucose is main source of energy –Reserves stored in liver and muscle cells as glycogen Other energy sources –Glycerol –Fatty acids –Amino acids

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Anabolism Essential nutrients –Cannot be made by body –Must be taken in diet Essential amino acids –Nine of 22 must be eaten Essential fatty acids –Linoleic acid and linolenic acid

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Minerals and Vitamins Minerals are chemical elements –Body structure –Fluid balance –Muscle contraction –Nerve impulse conduction –Blood clotting Vitamins are complex substances –Water soluble –Fat soluble Antioxidants –Stabilize free radicals

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Nutritional Guidelines Percentage of calories in daily diet Carbohydrate: 55 – 50% Fat: 30% or less Protein: 15 – 20%

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Carbohydrates Diet should be mainly complex, naturally occurring carbohydrates Normal blood glucose range 85 to 125 mg/dL Glycemic effect measures how rapidly food raises blood glucose level, stimulates release of insulin

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Fats Saturated –Most are from animal sources –Solid at room temperature Unsaturated –Derived from plants –Liquid at room temperature Hydrogenated –Artificially saturated –Trans-fatty acids

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Proteins Not stored in body Most animal proteins supply all essential amino acids Most vegetable proteins lack one or more essential amino acids

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Vitamin and Mineral Supplements Supplements are controversial Some populations may benefit Some vitamins cause toxic effects when taken in excess

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Food Guide Pyramid United States Department of Agriculture publishing guidelines since 1916 Newest version is 2005 Food Guide Pyramid Represents quantities of food recommended each day for good health 2006 is first version to include physical exercise as a component of a healthy diet. Other updates in 2006: –Stresses variety in the diet –Stresses moderation –Stresses eating fruits and vegetables –Includes choices of “nutrient-dense” foods –Does not include sugar, solid fats, or alcohol; termed “discretionary calories”

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The 2006 Food Guide Pyramid

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Alcohol Not a nutrient Interferes with metabolism Should be consumed in moderation

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Nutritional Disorders Excess of nutrients Shortage of nutrients Weight control Food allergies

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Food Allergies Allergens can be food or food additives Allergic reactions involve –Skin –Respiratory tract –Gastrointestinal tract Reactions can be fatal

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Malnutrition Can occur from missing nutrients or too much of wrong foods Protein and energy malnutrition (PEM) Marasmus Kwashiorkor

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Overweight and Obesity Causes are complex Incidence is increasing Shortens life span Measured by body mass index (BMI) –Overweight is BMI of 25 – 30 –Obese is BMI greater than 30

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Underweight Low reserves of energy Reproductive disturbances Nutritional deficiencies BMI less than 18.5

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Nutrition and Aging Nutritional deficiencies may develop Medications may interfere with appetite and absorption

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Body Temperature Heat is byproduct of chemical activities in body tissues Regulatory devices keep body temperature constant within narrow limits

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heat Production Amount of heat produced by organs affected by Exercise Hormone production Food intake Age

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Heat Loss More than 80% of heat loss occurs through skin –Conduction –Radiation –Convection –Evaporation 15-20% heat loss through respiration and elimination Heat loss prevention –Clothing –Fat layer under skin

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Temperature Regulation Body has internal mechanisms for regulating temperature

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins The Role of the Hypothalamus Regulation of Heat loss –Constrict skin blood vessels –Shiver –Increase cell metabolism Overheating –Stimulate sweat glands –Dilate skin blood vessels –Muscle relaxation

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Age Factors Newborns and elderly Reduced ability to produce heat Reduced ability to regulate overheating

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Normal Body Temperature Normal range is 36.3ºC to 37.6ºC (97.8ºF to 100.8ºF) Varies with time of day Varies by body part

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins FeverFever Higher than normal body temperature Causes –Infection –Malignancies –Brain injuries –Toxic reactions –Vaccine reactions –Central nervous system diseases Crisis Lysis

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Responses to Excessive Heat Heat cramps –Localized muscle cramping Heat exhaustion –Heat retention and fluid loss Heat stroke –Medical emergency that can be fatal

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins Responses to Excessive Cold Hypothermia –Excessively low body temperature –Used in some types of surgery Frostbite –Can cause permanent local tissue damage –Likely areas are face, ears, extremities

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins End of Presentation