Chapter 21a Endocrine System Regulation of Energy Metabolism and Growth.pdf

PowerPoint® Lecture Presentation CHAPTER 21a The Endocrine System: Regulation of Energy Metabolism and Growth © 2017 Pearson Education, Inc. Chapter Outline 21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 An Overview of Whole-Body Metabolism Energy Intake, Utilization, and Storage Energy Balance...

PowerPoint® Lecture Presentation CHAPTER 21a The Endocrine System: Regulation of Energy Metabolism and Growth © 2017 Pearson Education, Inc. Chapter Outline 21.1 21.2 21.3 21.4 21.5 21.6 21.7 21.8 21.9 An Overview of Whole-Body Metabolism Energy Intake, Utilization, and Storage Energy Balance Energy Metabolism During the Absorptive and Postabsorptive States Regulation of Absorptive and Postabsorptive Metabolism Thermoregulation Hormonal Regulation of Growth Thyroid Hormones Glucocorticoids © 2017 Pearson Education, Inc. 21.1 An Overview of Whole-Body Metabolism • Anabolism • Biomolecules that provide energy are also used in large-molecule synthesis • Depends on body needs • Mechanisms exist to regulate pathways • Regulation of metabolic pathways • Regulation of enzymes • Concentration and activity of enzymes • Compartmentation • Cellular, tissue, and organ © 2017 Pearson Education, Inc. 21.2 Energy Intake, Utilization, and Storage • Nutrients • Carbohydrates (glucose) • Proteins (amino acids) • Lipids (lipoproteins) • Following intake, nutrients can fulfill several functions • Catabolized for energy • Act as substrates for new molecules • Stored for energy (glycogen and fat) © 2017 Pearson Education, Inc. Uptake, Utilization, and Storage of Energy in Carbohydrates • Absorbed carbohydrates • Monosaccharides • Circulating in blood • Glucose • Enters cells via glucose transporters • • • • Oxidized to energy CO2 generated Stored as glycogen Glycogenolysis © 2017 Pearson Education, Inc. Uptake, Utilization, and Storage of Energy in Proteins • Amino acids circulate in blood • Uptake into cells • Protein synthesis • Proteolysis into amino acids • Ammonia and CO2 produced • Urea © 2017 Pearson Education, Inc. Uptake, Utilization, and Storage of Energy in Lipids • Absorbed lipids • Triglycerides • Circulating in blood as lipoproteins • Lipoprotein lipase • Fatty acids • Monoglycerides • After cell entry • Oxidized to energy • Combined with glycerol to form new triglycerides • Stored in adipocytes © 2017 Pearson Education, Inc. Uptake, Utilization, and Storage of Energy in Lipids • Delivery of lipids to cells • Lipids are transported in blood • Move from GI to liver, adipose tissue, and other cells in chylomicrons • Move from liver to body cells in VLDLs • Lipoprotein lipase is located on inner surfaces of capillaries • Triglycerides → monoglyceride + 2 fatty acids • Fatty acids diffuse into cells • Monoglycerides are metabolized in liver © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 1 Liver 2 NH3 Glucose Amino acids Lipoproteins NH3 CO2 + H2O + energy Glycogen Other metabolism Carbohydrates © 2017 Pearson Education, Inc. Urea Protein + LPL CO2 + H2O + energy CO2 + H2O + NH3 + energy Proteins Fatty Monoglyceride acids Triglyceride Lipids + Fatty Glycerol acids Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Glucose Carbohydrates © 2017 Pearson Education, Inc. Slide 2 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Glucose Carbohydrates © 2017 Pearson Education, Inc. Slide 3 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Glucose CO2 + H2O + energy Carbohydrates © 2017 Pearson Education, Inc. Slide 4 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Glucose CO2 + H2O + energy Other metabolism Carbohydrates © 2017 Pearson Education, Inc. Slide 5 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Glucose CO2 + H2O + energy Glycogen Other metabolism Carbohydrates © 2017 Pearson Education, Inc. Slide 6 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Amino acids Proteins © 2017 Pearson Education, Inc. Slide 7 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Amino acids Proteins © 2017 Pearson Education, Inc. Slide 8 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Amino acids Proteins © 2017 Pearson Education, Inc. Slide 9 Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 10 Liver 2 NH3 Amino acids NH3 Protein CO2 + H2O + NH3 + energy Proteins © 2017 Pearson Education, Inc. Urea Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 11 Liver 2 NH3 Amino acids NH3 Protein CO2 + H2O + NH3 + energy Proteins © 2017 Pearson Education, Inc. Urea Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 12 Liver Lipoproteins Lipids © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 13 Liver Lipoproteins Fatty Monoglyceride acids + LPL Lipids © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 14 Liver Lipoproteins Fatty Monoglyceride acids + LPL Lipids © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 15 Liver Lipoproteins Fatty Monoglyceride acids + LPL CO2 + H2O + energy Lipids © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 16 Liver Lipoproteins Fatty Monoglyceride acids + LPL CO2 + H2O + energy Triglyceride Lipids © 2017 Pearson Education, Inc. Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 17 Liver Lipoproteins Fatty Monoglyceride acids + LPL CO2 + H2O + energy Triglyceride Lipids © 2017 Pearson Education, Inc. + Fatty Glycerol acids Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 18 Liver Lipoproteins Fatty Monoglyceride acids + LPL CO2 + H2O + energy Triglyceride Lipids © 2017 Pearson Education, Inc. + Fatty Glycerol acids Figure 21.1 Transport, uptake, and cellular fates of biomolecules. Slide 19 Liver 2 NH3 Glucose Amino acids Lipoproteins NH3 CO2 + H2O + energy Glycogen Other metabolism Carbohydrates © 2017 Pearson Education, Inc. Urea Protein + LPL CO2 + H2O + energy CO2 + H2O + NH3 + energy Proteins Fatty Monoglyceride acids Triglyceride Lipids + Fatty Glycerol acids © 2017 Pearson Education, Inc. 21.3 Energy Balance • Energy input = energy output • Regulated by endocrine system • Energy input: energy content of consumed nutrients • Energy output: heat (60%) + work (40%) • Cellular work • Mechanical work • Chemical work • Transport work © 2017 Pearson Education, Inc. Figure 21.2 The forms of energy produced by the oxidation of nutrient molecules. Heat Nutrient molecules ATP Oxidation Energy Heat CO2 + H2O + NH3 © 2017 Pearson Education, Inc. Work: mechanical chemical transport Metabolic Rate • Energy expended per unit time • Basal metabolic rate (BMR) = rate of energy expenditure of a person awake, resting, lying down, who has fasted for 12 hours • Represents the minimum energy expenditure necessary to maintain body functions • Metabolic rate increases with increases in activity © 2017 Pearson Education, Inc. Negative and Positive Energy Balance • Energy output = work performed + heat released • For balance • Energy input = energy output • Energy input = work performed + heat released © 2017 Pearson Education, Inc. Negative and Positive Energy Balance • Positive balance • Energy intake > energy output • Energy in excess of output is stored • Negative balance • Energy intake < energy output • Need to obtain energy from stores © 2017 Pearson Education, Inc. 21.4 Energy Metabolism During the Absorptive and Postabsorptive States • During the absorptive state: energy is stored in macromolecules • During the postabsorptive state: these energy stores are mobilized © 2017 Pearson Education, Inc. Metabolism During the Absorptive State • Energy input > output as nutrients are absorbed • Glucose: primary energy source for cells • Excess nutrients taken up will be stored • Liver and muscle store glycogen • Adipose tissue stores triglycerides © 2017 Pearson Education, Inc. Figure 21.3 Major metabolic reactions of the absorptive state. Slide 1 Absorption of small nutrients Blood Glucose Fatty acids Amino acids Most body cells Liver and muscle Liver and adipose tissue Liver Muscle and other cells CO2 + H2O + energy Glycogen Fatty acids Protein Glycerol Fatty acids Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Triglycerides Figure 21.3 Major metabolic reactions of the absorptive state. Absorption of small nutrients Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Slide 2 Figure 21.3 Major metabolic reactions of the absorptive state. Slide 3 Absorption of small nutrients Blood Glucose Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Fatty acids Amino acids Figure 21.3 Major metabolic reactions of the absorptive state. Slide 4 Absorption of small nutrients Blood Glucose Most body cells CO2 + H2O + energy Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Fatty acids Amino acids Figure 21.3 Major metabolic reactions of the absorptive state. Slide 5 Absorption of small nutrients Blood Glucose Most body cells Liver and muscle CO2 + H2O + energy Glycogen Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Fatty acids Amino acids Figure 21.3 Major metabolic reactions of the absorptive state. Slide 6 Absorption of small nutrients Blood Glucose Fatty acids Most body cells Liver and muscle Liver and adipose tissue CO2 + H2O + energy Glycogen Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Glycerol Fatty acids Amino acids Figure 21.3 Major metabolic reactions of the absorptive state. Slide 7 Absorption of small nutrients Blood Glucose Fatty acids Most body cells Liver and muscle Liver and adipose tissue CO2 + H2O + energy Glycogen Glycerol Fatty acids Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Triglycerides Amino acids Figure 21.3 Major metabolic reactions of the absorptive state. Slide 8 Absorption of small nutrients Blood Glucose Fatty acids Most body cells Liver and muscle Liver and adipose tissue CO2 + H2O + energy Glycogen Glycerol Fatty acids Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Triglycerides Amino acids Muscle and other cells Protein Figure 21.3 Major metabolic reactions of the absorptive state. Slide 9 Absorption of small nutrients Blood Glucose Fatty acids Amino acids Most body cells Liver and muscle Liver and adipose tissue Liver Muscle and other cells CO2 + H2O + energy Glycogen Fatty acids Protein Glycerol Fatty acids Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Triglycerides © 2017 Pearson Education, Inc. Metabolism During the Postabsorptive State • Energy input < output • Glucose is spared for nervous system • Other tissues use fatty acids or other sources for energy • Stored nutrients are broken down and mobilized © 2017 Pearson Education, Inc. Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 1 Stored macromolecules Muscle (and other cells) Adipose tissue Triglycerides Proteins Amino acids Fatty acids Liver Muscle Glycogen Glycogen Glycerol Lactate, pyruvate Liver Glucose Ketones Blood Amino acids Fatty acids Non-nervous tissue CO2 + NH3 + H2O + energy Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Ketones Glucose Nervous tissue CO2 + H2O + energy Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 2 Stored macromolecules Muscle (and other cells) Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Adipose tissue Liver Muscle Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 3 Stored macromolecules Muscle (and other cells) Proteins Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Adipose tissue Triglycerides Liver Muscle Glycogen Glycogen Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 4 Stored macromolecules Muscle (and other cells) Proteins Amino acids Adipose tissue Triglycerides Fatty acids Physiological response Result © 2017 Pearson Education, Inc. Muscle Glycogen Glycogen Glycerol Lactate, pyruvate Liver Initial stimulus Liver Glucose Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 5 Stored macromolecules Muscle (and other cells) Proteins Amino acids Adipose tissue Triglycerides Fatty acids Blood Result © 2017 Pearson Education, Inc. Glycogen Glycogen Lactate, pyruvate Ketones Physiological response Muscle Glycerol Liver Initial stimulus Liver Glucose Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 6 Stored macromolecules Muscle (and other cells) Proteins Amino acids Adipose tissue Triglycerides Fatty acids Liver Muscle Glycogen Glycogen Glycerol Lactate, pyruvate Liver Glucose Ketones Blood Amino acids Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Fatty acids Ketones Glucose Figure 21.4 Major metabolic reactions of the postabsorptive state. Slide 7 Stored macromolecules Muscle (and other cells) Adipose tissue Triglycerides Proteins Amino acids Fatty acids Liver Muscle Glycogen Glycogen Glycerol Lactate, pyruvate Liver Glucose Ketones Blood Amino acids Fatty acids Non-nervous tissue CO2 + NH3 + H2O + energy Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Ketones Glucose Nervous tissue CO2 + H2O + energy 21.5 Regulation of Absorptive and Postabsorptive Metabolism • Hormonal regulation • Insulin: hormone of absorptive state • Glucagon: hormone of postabsorptive state • Other less important regulators • Epinephrine • Sympathetic nervous system © 2017 Pearson Education, Inc. The Role of Insulin • Peptide hormone secreted from β cells of the islets of Langerhans in the pancreas • Promotes synthesis of energy storage molecules (anabolic reactions) • Promotes glucose uptake by body cells © 2017 Pearson Education, Inc. The Role of Insulin • Insulin secretion increases during absorptive state • • • • Increased glucose in plasma Increased amino acids in plasma Parasympathetic nervous system Glucose-dependent insulinotropic peptide (GIP) • Secretion decreases during postabsorptive state • Sympathetic nervous system activity • Epinephrine © 2017 Pearson Education, Inc. Figure 21.5 Actions of insulin on target tissues. Slide 1 Beta cells in pancreas Insulin secretion Most tissues Glucose uptake (except brain, liver, exercising muscle) Amino acid uptake Protein synthesis Protein breakdown Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Fatty acid and triglyceride synthesis Lipolysis Liver and muscle Glycogen synthesis Glycogenolysis Liver Fatty acid and triglyceride synthesis Gluconeogenesis Figure 21.5 Actions of insulin on target tissues. Slide 2 Beta cells in pancreas Insulin secretion Most tissues Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Liver and muscle Liver Figure 21.5 Actions of insulin on target tissues. Slide 3 Beta cells in pancreas Insulin secretion Most tissues Glucose uptake (except brain, liver, exercising muscle) Amino acid uptake Protein synthesis Protein breakdown Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Liver and muscle Liver Figure 21.5 Actions of insulin on target tissues. Slide 4 Beta cells in pancreas Insulin secretion Most tissues Glucose uptake (except brain, liver, exercising muscle) Amino acid uptake Protein synthesis Protein breakdown Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Fatty acid and triglyceride synthesis Lipolysis Liver and muscle Liver Figure 21.5 Actions of insulin on target tissues. Slide 5 Beta cells in pancreas Insulin secretion Most tissues Glucose uptake (except brain, liver, exercising muscle) Amino acid uptake Protein synthesis Protein breakdown Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Fatty acid and triglyceride synthesis Lipolysis Liver and muscle Glycogen synthesis Glycogenolysis Liver Figure 21.5 Actions of insulin on target tissues. Slide 6 Beta cells in pancreas Insulin secretion Most tissues Glucose uptake (except brain, liver, exercising muscle) Amino acid uptake Protein synthesis Protein breakdown Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Fatty acid and triglyceride synthesis Lipolysis Liver and muscle Glycogen synthesis Glycogenolysis Liver Fatty acid and triglyceride synthesis Gluconeogenesis © 2017 Pearson Education, Inc. The Role of Insulin • Glucose • • • • • • Enters β cells by facilitated diffusion through GLUT2 Catabolized to ATP ATP closes K+ channels β cell depolarizes, with less K+ moving out Ca2+ channels open Secretion of insulin © 2017 Pearson Education, Inc. Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 1 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. Calcium triggers insulin release by exocytosis. GLUT2 Glucose Glucose-6-P Depolarization opens voltage-gated Ca2+ channels and calcium enters the cell. Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Ca2+ Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation K+ ATP ATP + + Depolarization + + + ATP-selective K+ channel ATP then acts as a ligand and binds to ATP-selective K+ channels, causing the channels to close and blocking K+ movement out of the cell. © 2017 Pearson Education, Inc. Voltagegated Ca2+ channel – – – – – Blocked K+ movement causes depolarization of the cell membrane. Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 © 2017 Pearson Education, Inc. Slide 2 Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 Glucose Glucose-6-P Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Glycolysis Pyruvate © 2017 Pearson Education, Inc. Slide 3 Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 4 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 Glucose Glucose-6-P Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation © 2017 Pearson Education, Inc. K+ ATP ATP Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 5 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 Glucose Glucose-6-P Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation K+ ATP ATP ATP-selective K+ channel ATP then acts as a ligand and binds to ATP-selective K+ channels, causing the channels to close and blocking K+ movement out of the cell. © 2017 Pearson Education, Inc. Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 6 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 Glucose Glucose-6-P Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation K+ ATP ATP + + Depolarization + + + ATP-selective K+ channel ATP then acts as a ligand and binds to ATP-selective K+ channels, causing the channels to close and blocking K+ movement out of the cell. © 2017 Pearson Education, Inc. – – – – – Blocked K+ movement causes depolarization of the cell membrane. Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 7 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. GLUT2 Glucose Glucose-6-P Depolarization opens voltage-gated Ca2+ channels and calcium enters the cell. Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Ca2+ Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation K+ ATP ATP + + Depolarization + + + ATP-selective K+ channel ATP then acts as a ligand and binds to ATP-selective K+ channels, causing the channels to close and blocking K+ movement out of the cell. © 2017 Pearson Education, Inc. Voltagegated Ca2+ channel – – – – – Blocked K+ movement causes depolarization of the cell membrane. Figure 21.6 Actions of glucose on insulin secretion. High [Glucose] Slide 8 Glucose is in high concentration outside the cell and moves into the cell via facilitated diffusion. Calcium triggers insulin release by exocytosis. GLUT2 Glucose Glucose-6-P Depolarization opens voltage-gated Ca2+ channels and calcium enters the cell. Glucose is converted to pyruvate through glycolysis and enters the mitochondrial matrix. Ca2+ Glycolysis Pyruvate Oxidative phosphorylation takes place in the mitochondrial matrix, which releases ATP into the cytosol. Oxidative phosphorylation K+ ATP ATP + + Depolarization + + + ATP-selective K+ channel ATP then acts as a ligand and binds to ATP-selective K+ channels, causing the channels to close and blocking K+ movement out of the cell. © 2017 Pearson Education, Inc. Voltagegated Ca2+ channel – – – – – Blocked K+ movement causes depolarization of the cell membrane. The Role of Insulin • Actions of insulin • Anabolism to build up energy stores • Glycogen synthesis • Triglyceride synthesis • Promotes glucose use for energy • Increases glucose uptake by cells • Decreases catabolism © 2017 Pearson Education, Inc. The Role of Glucagon • Peptide hormone secreted from α cells in islets of Langerhans • Promotes breakdown of energy storage molecules (catabolic reactions) • Promotes glucose sparing for nervous system by diverting body cells to utilize other sources of energy • Antagonist of insulin © 2017 Pearson Education, Inc. The Role of Glucagon • Glucagon secretion • Secretion increases during postabsorptive state • Sympathetic nervous system • Epinephrine • Secretion decreases during absorptive state • Increases glucose in plasma © 2017 Pearson Education, Inc. The Role of Glucagon • Actions of glucagon • Mobilization of energy stores • Glycogenolysis • Lipolysis • Synthesizes new glucose • Gluconeogenesis • Catabolic hormone © 2017 Pearson Education, Inc. Figure 21.7 Actions of glucagon on target tissues. Alpha cells in pancreas Glucagon secretion Liver Glycogenolysis Lipolysis Glycogen synthesis Triglyceride synthesis Gluconeogenesis Ketone synthesis Protein breakdown Protein synthesis Initial stimulus Physiological response © 2017 Pearson Education, Inc. Adipose tissue Negative Feedback Control of Blood Glucose Levels by Insulin and Glucagon • • • • Normal blood glucose: 70–110 mg/dL Hyperglycemia: glucose > 140 mg/dL Hypoglycemia: glucose < 60 mg/dL Blood glucose levels are maintained primarily by actions of insulin and glucagon © 2017 Pearson Education, Inc. Figure 21.8 Regulation of plasma glucose concentration. Slide 1 Plasma glucose Plasma glucose Beta cells in pancreas Negative feedback Negative feedback Insulin secretion Most tissues Glucose uptake into cells Liver and muscle Glycogen synthesis Glycogenolysis Plasma glucose Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Liver Gluconeogenesis Alpha cells in pancreas Glucagon secretion Liver Gluconeogenesis Adipose tissue Lipolysis Glycogenolysis Plasma fatty acids Plasma glucose Glucose spared Figure 21.8 Regulation of plasma glucose concentration. Plasma glucose Beta cells in pancreas Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Slide 2 Plasma glucose Alpha cells in pancreas Figure 21.8 Regulation of plasma glucose concentration. Plasma glucose Beta cells in pancreas Insulin secretion Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Slide 3 Plasma glucose Alpha cells in pancreas Glucagon secretion Figure 21.8 Regulation of plasma glucose concentration. Slide 4 Plasma glucose Plasma glucose Beta cells in pancreas Alpha cells in pancreas Insulin secretion Most tissues Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Liver and muscle Glucagon secretion Liver Liver Adipose tissue Figure 21.8 Regulation of plasma glucose concentration. Slide 5 Plasma glucose Plasma glucose Beta cells in pancreas Alpha cells in pancreas Insulin secretion Most tissues Glucose uptake into cells Liver and muscle Glycogen synthesis Glycogenolysis Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Glucagon secretion Liver Gluconeogenesis Liver Gluconeogenesis Adipose tissue Lipolysis Glycogenolysis Plasma fatty acids Figure 21.8 Regulation of plasma glucose concentration. Slide 6 Plasma glucose Plasma glucose Beta cells in pancreas Negative feedback Negative feedback Insulin secretion Most tissues Glucose uptake into cells Liver and muscle Glycogen synthesis Glycogenolysis Plasma glucose Initial stimulus Physiological response Result © 2017 Pearson Education, Inc. Liver Gluconeogenesis Alpha cells in pancreas Glucagon secretion Liver Gluconeogenesis Adipose tissue Lipolysis Glycogenolysis Plasma fatty acids Plasma glucose Glucose spared Negative Feedback Control of Blood Glucose Levels by Insulin and Glucagon • Increased blood amino acids • Characteristic of high-protein, low-carbohydrate meals • Increases insulin release • Increases amino acid uptake • Increases glucose uptake (potentially dangerous if carbohydrate intake is low) • Increases glucagon release • Low-carbohydrate diet = low blood glucose • More glucagon stimulated by amino acids • Counteracts insulin effect • Maintains proper blood glucose level © 2017 Pearson Education, Inc. Effects of Epinephrine and Sympathetic Nervous Activity on Metabolism • Suppresses insulin release • Stimulates glucagon release • Characteristic of postabsorptive state © 2017 Pearson Education, Inc. Epinephrine and Postabsorptive State • Decreased plasma glucose stimulates increased epinephrine release • Increased epinephrine stimulates liver • Glycogenolysis increases • Gluconeogenesis increases • Minor role compared to insulin and glucagon © 2017 Pearson Education, Inc. Diabetes Mellitus • Energy metabolism impaired • Insulin deficiency (type 1 diabetes mellitus) • Deficient insulin response (type 2 diabetes mellitus) • Primary sign: hyperglycemia • Normally suppresses glucagon release • Not so in diabetes • Decreased insulin • Decreases α cells' permeability to glucose • Triggers a falsely low glucose level • α cells increase glucagon release © 2017 Pearson Education, Inc.