Chapter 20 Nutrition and Metabolism Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Nutrients Nutrients are chemicals the body uses for growth, maintenance, and repair Essential nutrients: ones needed in the diet because the body cannot make sufficient amounts to meet body needs. There are six major types of nutrients: carbohydrates, lipids, proteins, minerals, vitamins, and water. Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Healthy Eating 4 Cal/ gram for protein or carbohydrate 9 Cal/gram for lipids Experted-suggested dietary calories: 50-60% Calories from carbohydrate Should be <15% monosaccharides <30% from fats (mostly triglycerides) Should be < 10% from saturated fats 12-15% from protein Copyright 2010, John Wiley & Sons, Inc.

Guidelines for Healthy Eating Eat a variety of foods Maintain a healthy weight Choose foods low in fat, saturated fat, and cholesterol Eat plenty of fruits, vegetables, and grains Use sugars in moderation Use sodium in moderation: < 2.3 grams/day Use alcoholic beverages in moderation only: 1 drink/day for women; 2 drinks/day for men Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. My Pyramid Introduced in 2005 by USDA Web: http://www.mypyramid.gov/ Personalized approach to healthy food choices Based on gender, age, and activity Food from each of 6 bands needed each day Example: healthy, moderately active 18-year-old Female requires about 2000 Calories/day Male requires about 2800 Calories/day Steps a reminder of daily activity needed Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. My Pyramid Copyright 2010, John Wiley & Sons, Inc.

Categories of Nutrients Carbohydrates, proteins, lipids Calories for energy + building materials. Water Minerals Ca, P, K, S, Na, Cl, Fl, Mg, Fe, Cr, I, Mn, Co, Cu, Zn, Se. Table 21.1 Vitamins: essential or dietary provitamins Lipid-soluble: A, D, E, K Water-soluble: B vitamins and C Functions: Table 20.2 Copyright 2010, John Wiley & Sons, Inc.

Categories of Nutrients: Six Carbohydrates, proteins, lipids Give calories for energy + building materials. Minerals: inorganic (Table 20.1) Ca, P, K, S, Na, Cl, Fl, Mg, Fe, I, Mn, Co, Cu, Zn, Se, Cr Electrolytes, components of skeleton, enzymes Vitamins: organic (Table 20.2) Lipid soluble: A, D, E, K Water soluble: B group, C Many function as coenzymes Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Metabolism Facilitated by enzymes and coenzymes NAD+ from B vitamin niacin FAD from riboflavin (B2) Sequence of enzymatic steps is a pathway Two categories Anabolism: synthesis of more complex chemicals Catabolism: breakdown with energy release 40%  cellular functions (ATP) 60%  heat Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Metabolism Copyright 2010, John Wiley & Sons, Inc.

Metabolism Interactions Animation Introduction to Metabolism You must be connected to the internet to run this animation. Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Metabolism Copyright 2010, John Wiley & Sons, Inc.

Carbohydrate Metabolism Glucose: the body’s preferred source for ATP production Possible uses of glucose Used immediately for ATP production Stored as glycogen in liver or skeletal muscle Leftover: forms triglycerides in adipose tissue Enters cells by facilitated diffusion Insulin increases rate of transport Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Glucose Catabolism Overall catabolism of glucose Glucose + 6 O2  36-38 ATP + 6 CO2 + 6 H2O Glycolysis (in cytosol) Glucose  pyruvate + ATP + NADH + H+ Anaerobic cellular respiration 2. Transition step (in mitochondria): Pyruvate  acetyl CoA + CO2 + NADH + H+ 3. Krebs cycle (in mitochondria): aerobic CO2 + ATP + NADH + H+ + FADH2 4. Electron transport chain (in mitochondria): aerobic NADH + H+ + FADH2 + O2  ATP + H2O Copyright 2010, John Wiley & Sons, Inc.

Glucose Anabolism and Regulation of Blood Glucose Levels When blood glucose is high Glucose + ATP  glycogen (in liver, muscle) Effect: blood glucose level is lowered When blood glucose is low Hormones glucagon and epinephrine stimulate Glycogen breakdown to  glucose Hormones: glucagon and cortisol stimulate Gluconeogenesis in liver cells by Glycerol (from fat)  glucose Some amino acids  glucose Copyright 2010, John Wiley & Sons, Inc.

Glucose Anabolism and Regulation of Blood Glucose Levels Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Lipid Metabolism Lipolysis (catabolism): triglycerides  glycerol + fatty acids Glycerol  glycolysis or gluconeogenesis Fatty acids  acetyl-CoA (2-carbon)  Krebs cyle  ATP Liver converts some acetyl-CoA  ketone bodies Diabetics can form excessive ketone bodies  acetone (causes sweet breath) + acidosis (with possible coma and death) Lipogenesis (anabolism) Excess fats, carbohydrates, or proteins  fats Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Lipid Metabolism Copyright 2010, John Wiley & Sons, Inc.

Lipid Transport in Blood Lipids are not water soluble so need protein coating  lipoproteins Types of lipoproteins Chylomicrons: carry dietary fat to adipose Very low-density lipoproteins (VLDL) Made in liver; transport fat to adipose tissue Converted to LDLs Low-density lipoproteins (LDL): “bad” Carry 75% of cholesterol to cells for use there High-density lipoproteins (HDL): “good” Remove excess cholesterol and transport to liver for disposal Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Protein Metabolism Catabolism: protein breakdown Deamination in liver to remove NH2  NH3 Liver converts toxic NH3  urea  urine Rest of amino acid  Krebs cycle  ATP Anabolism: protein synthesis to form many different proteins in the body Essential amino acids (10): must come in diet Nonessential amino acids (10): can be made in the body by modifications of essential amino acids Copyright 2010, John Wiley & Sons, Inc.

Metabolism and Body Heat Gain Heat is one form of energy Measured in calories 1 calorie (cal) = energy needed to raise 1 g of water 1oC For foods use kilocalories (1000 cal) = Calorie Heat is produced (gained) from catabolism Rate of production = metabolic rate Basal metabolic rate (BMR) = heat produced from catabolism when resting and fasting BMR for adult :1200-1800 Cal/day Copyright 2010, John Wiley & Sons, Inc.

Metabolism and Body Heat Metabolic rate is affected by the following Exercise: rate can increase 15-20 times Hormones: thyroid is primary Nervous System: ANS can increase Body temperature: warming increases Ingestion of food: gives 10-20% increase Age: metabolic rate of child higher than adult’s Gender, pregnancy, climate, sleep, malnutrition Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Body Heat Loss Must be continuous as catabolism constantly produces heat Routes of heat loss Radiation: loss of body heat to air Conduction: loss of body heat to surface, such as cold metal seat Convection Loss of body heat to air moving from a fan or from breeze outside shower curtain Evaporation Conversion of water to vapor as in sweating; helps prevent overheating with exercise Copyright 2010, John Wiley & Sons, Inc.

Control of Body Temperature Balance regulated by hypothalamus Detects changes in temperature (“thermostat”) Warming mechanisms Sympathetic vasoconstriction   heat loss Epinephrine   metabolism Increased muscle tone  metabolism Can lead to shivering   heat from muscles  TSH  thyroid gland   thyroid hormone in blood   metabolism Cooling mechanisms The reverse + sympathetic-stimulated sweating Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. End of Chapter 20 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein. Copyright 2010, John Wiley & Sons, Inc.