Lecture Outline

CHAPTER OVERVIEW: This chapter defines metabolism and nutrition and explains how the major nutrient groups are utilized within the body. The important relationships among nutrients, vitamins and minerals are described and the relations (and interrelations) with the processes of energy extraction, the use of energy, and the control of metabolism in cells are explained.

OUTLINE (one to three fifty-minute lectures):

Chapt. Object.

Topic Outline, Chapter 25

 

Figures & Tables

Trnspcy. Acetates

Trnspcy.

Masters

 

I. Nutrition

 

 

 

1

      A. Component Processes

 

 

 

 

          1. Digestion

 

 

 

 

          2. Absorption

 

 

 

 

          3. Transport

 

 

 

 

          4. Cell Metabolism

 

 

 

 

      B. Nutrients

 

 

 

 

          1. Essential Nutrients

 

 

 

 

          2. Food Guide Pyramid

Fig. 25.1, p.827

 

TM-88

2

      C. Kilocalories

 

 

 

 

          1. Unit of Energy

 

 

 

 

              a. 1 cal. = Energy Needed to Raise 1 g of Water 1_ C

 

 

 

 

              b. 1 Kcal. (or Cal.) = 1000 cal.

 

 

 

 

          2. Food Sources of Energy

Table 25.1, pp.828-829; Clinical Note, p.827

 

 

3

      D. Carbohydrates

 

 

 

 

          1. Sources in the Diet

 

 

 

 

              a. Simple Sugars

 

 

 

 

              b. Complex Carbohydrates

 

 

 

 

          2. Uses in the Body

 

 

 

 

              a. Primary Energy Source

 

 

 

 

              b. Part of Nucleotides

 

 

 

 

              c. Glycoproteins

 

 

 

 

          3. Recommended Amounts

Clinical Focus, p.847

 

 

 

              a. 125 to 175 g / Day

 

 

 

 

              b. Complex Forms Preferred

 

 

 

3

      E. Lipids

 

 

 

 

          1. Sources in Diet

 

 

 

 

              a. 95% as Triacylglycerols

Fig. 2.16, p.45

 

 

 

                  1). Saturated Fats Primarily of Animal Origin

Clinical Note, p.830

 

 

 

                  2). Unsaturated Fats Primarily of Plant Origin

 

 

 

 

              b. Remaining 5%

 

 

 

 

                  1). Cholesterol (a Steroid)

 

 

 

 

                  2). Phospholipids (like Lecithin)

 

 

 

 

          2. Uses in the Body

 

 

 

 

              a. Energy Sources

 

 

 

 

              b. Triacylglycerols in Adipose Tissue

 

 

 

 

                  1). Energy Storage

 

 

 

 

                  2). Protection of Organs

 

 

 

 

                  3). Thermal Insulation

 

 

 

 

              c. Cholesterol

 

 

 

 

                  1). Membranes

 

 

 

 

                  2). Bile Salts

 

 

 

 

                  3). Steroid Hormones

 

 

 

 

              d. Prostaglandins = Fatty Acid Derivatives

 

 

 

 

              e. Phospholipids in Plasma Membranes and Myelin Sheaths

 

 

 

 

          3. Recommended Amounts

Clinical Focus, pp.849-850

 

 

 

              a. <30% of Total Calorie Intake

 

 

 

 

              b. Essential Fatty Acids

Clinical Note, p.831

 

 

 

                  1). Linoleic Acid

 

 

 

 

                  2). Alpha-Linoleic Acid

 

 

 

 

                  3). Eicosapentaenoic Acid

 

 

 

3

      F. Proteins

 

 

 

 

          1. Sources in the Diet

 

 

 

 

              a. Nine Essential Amino Acids = Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine

 

 

 

 

              b. Remaining Eleven Naturally Occurring Amino Acids are Non-Essential

 

 

 

 

              c. Complete Protein Food Contains Adequate Amounts of All Nine Essential Amino Acids = "Meat Group" - Meat, Fish, Poultry, Milk, Cheese, and Eggs

 

 

 

 

          2. Uses in the Body

 

 

 

 

              a. Collagen and Structural Proteins

 

 

 

 

              b. Contractile Apparatus of Muscle Cells

 

 

 

 

              c. Enzymes and Functional Proteins

 

 

 

 

              d. Plasma Buffers

 

 

 

 

              e. Hemoglobin = O2 Transport

 

 

 

              f. Membrane Proteins

 

 

 

 

                  1). Carrier Molecules

 

 

 

 

                  2). Receptors

 

 

 

 

                  3). Ion Channels

 

 

 

 

              g. Immune Response Compounds

 

 

 

 

                  1). Antibodies

 

 

 

 

                  2). Lymphokines

 

 

 

 

                  3). Complement System

 

 

 

 

          3. Recommended Amounts

 

 

 

 

              a. 0.8 g / Kg Body Weight - About 12% of Total Kcals.

 

 

 

 

              b. Balance of Several Incomplete Foods can Provide all Essential Amino Acids

 

 

 

 

              c. Nitrogen Balance - When Amount of Nitrogen from Protein Ingested = Amount of Nitrogen Excreted from Body

 

 

 

4

      G. Vitamins

Table 25.2, pp.832-833

 

 

 

          1. Required for Normal Metabolism in Small Amounts

 

 

 

 

          2. Many Function as Coenzymes

 

 

 

 

          3. Many Heat Sensitive

Clinical Note, p.833

 

 

 

          4. Fat Soluble = A,D,E, and K

 

 

 

 

              a. Can be Stored

 

 

 

 

              b. Hypervitaminosis Possible

 

 

 

 

          5. Water Soluble = B Complex and C, Cannot be Stored

Predict Quest. 1

 

 

5

      H. Minerals

Table 25.3, p.834

 

 

 

          1. Inorganic Nutrients

 

 

 

 

          2. Necessary for Normal Metabolism

 

 

 

 

          3. 4-5 % of Total body Weight

 

 

 

 

          4. Adequately Provided in a Balanced Diet

Clinical Note, p.834

 

 

 

 

 

 

 

 

II. Metabolism

Fig. 25.3, p.836

TA-344

 

 

      A. Anabolism - Energy-using Processes by Which Small Molecules Made into Larger Molecules

 

 

 

 

      B. Catabolism - Energy-Releasing Processes by Which Large Molecules Broken into Smaller Molecules

 

 

 

 

      C. Cellular Respiration = Cellular Metabolism

 

 

 

 

      D. ATP = Energy "Currency" of the Cell

Fig. 25.2, p.835

TA-343

 

 

 

 

 

 

 

III. Carbohydrate Metabolism

 

 

 

6

      A. Glycolysis

 

 

 

 

          1. Input of ATP for Phosphorylation

Fig. 25.4, p.837

 

TM-89 TM-90

 

          2. Sugar Cleavage

 

 

 

 

          3. Reduced Nicotinamide Adenine Dinucleotide (NADH) Production

 

 

 

 

          4. ATP and Pyruvic Acid Production

Table 25.4, p.839

 

 

9

      B. Anaerobic Respiration

Fig. 25.5, p.839

 

TM-91

 

          1. Absence of O2

 

 

 

 

          2. Lactic Acid Production

 

 

 

 

          3. Oxygen Debt Created

 

 

 

 

          4. Net Gain of 2 ATP

 

 

 

 

      C. Aerobic Respiration

 

 

 

 

          1. Acetyl Coenzyme A (Acetyl-CoA) Formation with NADH Production

Fig. 25.6, p.840

 

TM-92

7

          2. Citric Acid Cycle

 

 

 

 

              a. Direct ATP Production

 

 

 

 

              b. Production of NADH and Reduced Flavin Adenine Dinucleotide (FADH2)

 

 

 

 

              c. Carbon Dioxide Production

 

 

 

8

          3. Electron Transport Chain

Fig. 25.7, p.841

TA-345

 

 

              a. Oxidation of NADH and FADH2

 

 

 

 

              b. O2 as Final Electron Acceptor

 

 

 

 

              c. H2O Formed

 

 

 

 

              d. H+ Movement Leads to ATP Formation ñ Chemiosmotic Model

Predict Quest. 2

 

 

9

          4. Summary of ATP Production from One Molecule of Glucose

Clinical Note, p.842

 

 

 

              a. Aerobic Respiration Yields 36 or 38 Molecules of ATP (Depending on Cell Type)

 

 

 

 

              b. 6 CO2 and 6 H2O Also Produced

 

 

 

10

IV. Lipid Metabolism

Fig. 25.8, p.843

TA-346

 

 

      A. Long-Term Storage for Energy

 

 

 

 

          1. 99% Lipid, Primarily Triacylglycerols

 

 

 

 

          2. 1% Glycogen (Shorter-Term)

 

 

 

 

      B. Free Fatty Acids in Blood Usage Form

 

 

 

 

      C. Beta-Oxidation of Fatty Acids to Acetyl-CoA

 

 

 

 

      D. Ketogenesis

Clinical Note, p.842

 

 

 

          1. Formation of Ketone Bodies when Excess Acetyl-CoA Present

 

 

 

 

          2. Converted Back to Acetyl-coA in Skeletal Muscle and Used in Citric Acid Cycle

 

 

 

 

 

 

 

 

11

V. Protein Metabolism

 

 

 

 

      A. Amino Acids (AA) used to synthesize Needed Proteins

 

 

 

 

      B. Biosynthesis of Non-Essential AA

 

 

 

 

          1. From Keto Acids

Fig. 25.10, p.844

 

TM-93

 

          2. Transamination

Fig. 25.11, p.845

 

TM-94

 

      C. Amino Acids as an Energy Source

Fig. 25.9, p.844

TA-347

 

 

 

 

 

 

12

VI. Interconversion of Nutrient Molecules

Clinical Note, p. 843; Fig. 25.12, p.845

TA-348

 

 

      A. Glycogenesis

 

 

 

 

      B. Lipogenesis

 

 

 

 

 

 

 

 

13

VII. Metabolic States

 

 

 

 

      A. Absorptive State

Fig. 25.13, p.846

TA-349

 

 

          1. Nutrients being Absorbed

 

 

 

 

          2. For 4 hrs. Following Each Meal

 

 

 

 

          3 Nutrient Use

 

 

 

 

              a. Glucose used as Energy Source by Cells

 

 

 

 

              b. Fats Deposited in Adipose Tissue

 

 

 

 

              c. Amino Acids for

 

 

 

 

                  1). Protein Synthesis

 

 

 

 

                  2). Liver Conversion to Fats or Carbohydrates

 

 

 

 

      B. Post-Absorptive State

Fig. 25.14, p.847

TA-350

 

 

          1. Between Meals

 

 

 

 

          2. Maintenance of constant Blood Glucose

 

 

 

 

              a. Normal Blood Glucose = 70-110 mg / 100 ml

 

 

 

 

              b. Interconversion of Other Compounds into Glucose

 

 

 

 

 

 

 

 

14

VIII. Metabolic Rate

 

 

 

 

      A. Metabolic Rate = Total Amount of Energy Produced and Used by Body per Unit Time

 

 

 

 

          1. ATP Exists for Less than 1 min so ATP Production Roughly Equivalent to Energy Use.

 

 

 

 

          2. One L O2 commonly Produces 4.825 Kcal of Energy

 

 

 

 

          3. Body Energy Balance

 

 

 

 

              a. If Input of Kcal > Usage Body Weight is Gained

Clinical Note, p.848

 

 

 

              b. If Input of Kcal < Usage Body Weight is Lost

 

 

 

 

      B. Basal Metabolic Rate

 

 

 

 

          1. Calculated as Kcal Expended per m2 of Body Surface Area/ hr. After 12 hr. Fast

 

 

 

 

          2. Energy Needed to Keep Resting Body Functional - About 60% of Total Energy Expenditure

 

 

 

 

          3. Males have Higher BMR than Females (Pregnancy can Increase BMR by 20%)

 

 

 

 

          4. Long-Term and Short-Term Hormonal Regulation of BMR

 

 

 

 

      C. Thermic Effect of Food

 

 

 

 

          1. Energy Cost to Assimilate Food

 

 

 

 

              a. Increased Muscular Contraction

 

 

 

 

              b. Increased Glandular Secretion

 

 

 

 

              c. Increased Active Transport

 

 

 

 

              d. Increased Liver Interconversion of Nutrients

 

 

 

 

          2. About 10% of Body Energy Expenditure

 

 

 

 

      D. Muscular Activity

 

 

 

 

          1. Muscular Activity Consumes 30% of Body's Energy

 

 

 

 

              a. Skeletal Muscle Activity

 

 

 

 

              b. Contraction of the Heart

 

 

 

 

              c. Muscles of Respiration

 

 

 

 

          2. Aspect of Energy Usage Over Which Most Conscious Control

 

 

 

 

 

 

 

 

15

IX. Body Temperature Regulation

 

 

 

 

      A. Humans as Homeotherms

 

 

 

 

          1. Enzymes are Temperature Sensitive

 

 

 

 

          2. Body Temperature Kept within Narrow Range

 

 

 

 

      B. Result of Balance Between Heat Production and Heat Loss

Fig. 25.16, p.851 Predict Quest. 3; Predict Quest. 4

TA-351

 

 

      C. Mechanism of Heat Loss

Fig. 25.15, p.850

 

 

 

          1. Radiation

 

 

 

 

          2. Conduction

 

 

 

 

          3. Convection

 

 

 

 

          4. Evaporation

 

 

 

 

      D. Thermoregulatory Control Center in Posterior Hypothalamus Maintains Core Body Temperature Set-Point

Clinical Focus, p.852

 

 

 

 

 

 

 

IMPORTANT CONSIDERATIONS: If there is only one lecture session available for these topics, stress the highlights of the energy relationships and the relationship between metabolism and body temperature. If three sessions are available, use one for review of nutrients and their routes of entry into the body, one on cellular metabolism and one on metabolic states, metabolic rates and body temperature regulation.

The details of the catabolism of organic molecules are found in Chapter 24. Have students review this material if necessary. Discuss the meaning of "essential" nutrients as a foreshadowing of the interconversion processes to be discussed later in this chapter.

Students may not be familiar with heat as a form of metabolic waste, so the relationship between metabolic rate and body temperature may not be immediately apparent to them. Humans are homeothermic endotherms. Students should be asked to relate the maintenance of a constant body temperature (usually higher than the environment) to homeostasis and efficiency of metabolism.

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