Chapter 22 Energy balance Metabolism Homeostatic control of

Chapter 22 § Energy balance § Metabolism § Homeostatic control of metabolism § Regulation of body temperature Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Brain Controls Food Intake § Hypothalamus has two centers that regulate food intake: § Feeding center: Tonically active § Satiety center: Inhibits the feeding center § Glucostatic theory: When blood glucose level decreases, the satiety center is suppressed. § Lipostatic theory: a signal from the body’s fat stores to the brain modulates eating behavior to maintain certain body weight. Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Brain Controls Food Intake Role of peptides in regulation of food intake Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -1

Brain Controls Food Intake Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Energy Balance § Energy input equals energy output § Energy output = work + heat § Transport work: moving molecules across cell membrane § Mechanical work: movement § Chemical work: used for growth, maintenance, and storage of information and energy (ATP bonds, glycogen bonds). Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Metabolic Rate: Individual’s Energy Expenditure § Age and gender § Amount of lean muscle mass § Activity level § Diet § Hormones § Genetics § Energy intake and level of physical activity § Measure of Metabolic Rate: Rate of oxygen consumption and/or carbon dioxide production § Basal Metabolic Rate: Lowest metabolic rate (for example: rate during rest) Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Energy Storage § Glycogen in liver and muscle § Fat Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Metabolism § Extract energy from nutrients § Use energy for work and synthesis § Store excess energy § Anabolic (smaller to larger molecules) versus catabolic § Fed (just ate) versus fasted state Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Summary of Metabolism DIET Carbohydrates Fats Proteins Lipogenesis Free fatty acids + glycerol Fat stores Lipogenesis Excess glucose Glycogenesis Glycogen stores Lipolysis Urine Protein synthesis Body protein Glycogenolysis Glucose pool Free fatty acid pool Excess nutrients Amino acids Metabolism in most tissues Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Gluconeogenesis Range of normal plasma glucose Amino acid pool Brain metabolism Figure 22 -2

Summary of Metabolism DIET Carbohydrates Fat stores Lipogenesis Excess glucose Glycogenesis Glycogen stores Urine Glycogenolysis Glucose pool Range of normal plasma glucose Metabolism in most tissues Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Brain metabolism Figure 22 -2 (1 of 4)

Summary of Metabolism DIET Fats Lipogenesis Free fatty acids + glycerol Fat stores Lipolysis Free fatty acid pool Excess nutrients Metabolism in most tissues Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -2 (2 of 4)

Summary of Metabolism DIET Proteins Amino acids Protein synthesis Body protein Glucose pool Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Gluconeogenesis Range of normal plasma glucose Amino acid pool Figure 22 -2 (3 of 4)

Summary of Metabolism DIET Carbohydrates Fats Proteins Lipogenesis Free fatty acids + glycerol Fat stores Lipogenesis Excess glucose Glycogenesis Glycogen stores Lipolysis Urine Protein synthesis Body protein Glycogenolysis Glucose pool Free fatty acid pool Excess nutrients Amino acids Metabolism in most tissues Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Gluconeogenesis Range of normal plasma glucose Amino acid pool Brain metabolism Figure 22 -2 (4 of 4)

Metabolism Summary of biochemical pathways for energy production Glycogen Glucose 6–phosphate Liver only G L Y C O L Y S I S Glycerol Some amino acids NH 3 Cytoplasm 2 ATP Anaerobic conditions Pyruvate Lactate Aerobic conditions Pyruvate Co. A Electron transport system O 2 Acetyl Co. A Citric acid cycle NH 3 ATP + H 2 O Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Mitochondria Fatty acids Ketone bodies CO 2 (in liver) 2 ATP Some amino acids Figure 22 -3

Metabolism Push-pull control of metabolism Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -4

Metabolism Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Transport and Fate of Dietary Fats Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -5

Metabolism The relationship between LDL-C and risk of developing coronary heart disease Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -6

Fasted-State Metabolism Adipose lipids become free fatty acids and glycerol that enter blood. FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Free fatty acids Glycogenolysis b-oxidation Energy production Glucose Triglyceride stores Free fatty acids Glycerol Gluconeogenesis Ketone bodies Energy production Glycogen Gluconeogenesis Proteins Pyruvate or Lactate Glucose Ketone bodies Energy production Brain can use only glucose and ketones for energy. Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Amino acids Muscle glycogen can be used for energy. Muscles also use fatty acids and break down their proteins to amino acids that enter the blood. Figure 22 -7

Fasted-State Metabolism FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Glycogenolysis Energy production Glucose Energy production Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -7 (1 of 5)

Fasted-State Metabolism FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Glycogenolysis Energy production Glucose Glycogen Gluconeogenesis Pyruvate or Lactate Glucose Energy production Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -7 (2 of 5)

Fasted-State Metabolism FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Glycogenolysis Energy production Glucose Glycogen Gluconeogenesis Proteins Pyruvate or Lactate Glucose Amino acids Energy production Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -7 (3 of 5)

Fasted-State Metabolism Adipose lipids become free fatty acids and glycerol that enter blood. FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Free fatty acids Glycogenolysis Energy production Triglyceride stores Free fatty acids Glycerol Gluconeogenesis Energy production Glucose Glycogen Gluconeogenesis Proteins Pyruvate or Lactate Glucose Energy production Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Amino acids Muscle glycogen can be used for energy. Muscles also use fatty acids and break down their proteins to amino acids that enter the blood. Figure 22 -7 (4 of 5)

Fasted-State Metabolism Adipose lipids become free fatty acids and glycerol that enter blood. FASTED-STATE METABOLISM Liver glycogen becomes glucose. Liver glycogen stores Free fatty acids Glycogenolysis b-oxidation Energy production Glucose Triglyceride stores Free fatty acids Glycerol Gluconeogenesis Ketone bodies Energy production Glycogen Gluconeogenesis Proteins Pyruvate or Lactate Glucose Ketone bodies Energy production Brain can use only glucose and ketones for energy. Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Amino acids Muscle glycogen can be used for energy. Muscles also use fatty acids and break down their proteins to amino acids that enter the blood. Figure 22 -7 (5 of 5)

Homeostatic Control Anatomy of the pancreas Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -8 b–c

Homeostatic Control Mechanism is controlled by insulin and glucagon, both of which are secreted by the pancreas Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -9 a

Homeostatic Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -9 b

Homeostatic Control Glucose, glucagon, and insulin levels over a 24 -hour period Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -10

Homeostatic Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Insulin Secretion § Increased glucose concentrations § Increased amino acids concentrations § Feedforward effects of GI hormones: GI hormones stimulate release of insulin in anticipation of increased glucose concentration § Parasympathetic activity stimulates secretion of insulin § Sympathetic activity inhibits secretion of insulin Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Homeostatic Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Insulin Promotes Anabolism § Increases glucose transport into most, but not all, insulin-sensitive cells § Enhances cellular utilization and storage of glucose § Enhances utilization of amino acids § Promotes fat synthesis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Homeostatic Control Fed-state metabolism under the influence of insulin promotes glucose metabolism by cells Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -14

Homeostatic Control Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Endocrine Response to Hypoglycemia Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -15

Type 2 Diabetes § Accounts for 90% of all diabetics § Insulin resistance § Complications include atherosclerosis, neurological changes, renal failure, and blindness § Therapy § Diet and physical exercise § Drugs Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Normal and Abnormal Results of Glucose Tolerance Tests Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -17

Regulation of Body Temperature: Energy Balance in the Body Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -18

Regulation of Body Temperature: Heat Balance in the Body temperature is a balance between heat production, gain, and loss Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -19

Regulation of Body Temperature: Thermoregulatory Reflexes Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -20 (1 of 2)

Regulation of Body Temperature: Thermoregulatory Reflexes Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -20 (2 of 2)

Regulation of Body Temperature § Alterations in cutaneous blood flow conserve or release heat § Sweat contributes to heat loss § Heat production § Voluntary muscle contraction and normal, metabolic pathways § Regulated heat production § Shivering versus nonshivering thermogenesis Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings

Regulation of Body Temperature Homeostatic responses to environmental extremes Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -21 (1 of 2)

Regulation of Body Temperature Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 22 -21 (2 of 2)

Regulation of Body Temperature § Body’s thermostat can be reset § Pathological conditions § Hyperthermia § Heat exhaustion § Heat stroke § Malignant hyperthermia § Hypothermia Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings