Anatomy and Physiology Marieb’s Human Anatomy and Physiology Ninth Edition Marieb w Hoehn Chapter 24 Nutrition & Metabolism Lecture 12 Part 1: Overview, Carbohydrates, and Fats Slides 1-15; 80 min (with review of syllabus and Web sites) [Lecture 1] Slides 16 – 38; 50 min [Lecture 2] 118 min (38 slides plus review of course Web sites and syllabus)

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

Overview of General Metabolic Pathways Overall goal of catabolism: generate a pool of 2- or 3-carbon molecules and ATP  Lipo-genesis Glycogenolysis   Glycogenesis Lipolysis  Pyruvate is used to synthesize amino acids and Acetyl CoA Pyruvate can also be used to synthesize glucose via gluconeogenesis. Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Carbohydrates Sources Excesses lead to sugars (simple) obesity 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 In body: about 325 g. muscle glycogen, 90-100 g of liver glycogen, and 15-20 g of blood glucose. Avg American eats about 100 lbs of sugar per year (60 lbs sucrose, 40 lbs corn syrup) compared with 4 lbs per year about a century ago. RDA - The RDA, the estimated amount of a nutrient (or calories) per day considered necessary for the maintenance of good health by the Food and Nutrition Board of the National Research Council/ National Academy of Sciences. The RDA is updated periodically to reflect new knowledge. It is popularly called the Recommended Daily Allowance. Recommended (Dietary) Daily Allowance (RDA) is 125-175g *

Utilization of Carbohydrates Glucose is the body’s CHO energy source Figure from: Hole’s Human A&P, 12th edition, 2010

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?

Utilization of Lipids Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007 Via what structures is fat absorbed into the circulation from the digestive tract? In the absence of sufficient CHO, oxaloacetic acid (the ‘pickup’ molecule for Acetyl CoA in the TCA cycle) is converted to glucose and is no longer available to bind with Acetyl CoA. This causes acetyl CoA to be converted into ketone bodies resulting in ketoacidosis. Know these terms (see table of these terms later in this lecture) Oxaloacetic acid *

Beta-Oxidation of Fatty Acids Mitochondrion Long chain fatty acids (FA) require carnitine for transport into mitochondria FA are broken down in a step-wise manner, 2 carbons at a time in beta-oxidation Oxidation of FA yields about 1.5-2.0 times the energy from a comparable amount of glucose

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)

So, what’s going on here? 14g CHO x 4 cal/g = 56 cal Why do the calories for 12 oz. of this beer seem to be more than what you would suppose based on the CHO and protein content? 14g CHO x 4 cal/g = 56 cal 1g protein x 4 cal/g = 4 cal Total 60 cal Alcohol! About 7 cal/g

Lipoprotein Traffic TG-rich Cholesterol-rich 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.

Summary of Lipoproteins Designation Origin Action Chylomicron GI tract Transports dietary fats (mainly triglycerides) to liver for processing Very Low Density Lipoprotein (VLDL) Liver Transports triglycerides from liver to adipose cells Low Density Lipoprotein (LDL) Transports cholesterol from liver to cells in body High Density Lipoprotein (HDL) Removes excess cholesterol from cells and transports to liver Know this chart

Utilization of Lipids The liver uses fatty acids to synthesize a variety of lipids Chem Figures From: http://en.wikipedia.org/wiki/ Linoleic (Ω 6) Essential fatty acids are used for: 1) synthesis of membrane components 2) synthesis of eicosanoids Linolenic acid, EPA, and DHA (Ω 3) Figure From: Hole’s Human A&P, McGraw Hill, 2012

Metabolism and fate of macronutrients 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