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Chapter 17 Nutrition and Metabolism Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Topics Introduction Cellular Metabolism Diet and Nutrition Bioenergetics Aging and Nutritional Requirements Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Introduction Cells require oxygen and nutrients to carry out energy-generating processes – Nutrients obtained from diet Absorbed at the digestive tract Distributed by the cardiovascular system Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Introduction ATP energy supports: – – – – – Growth Cell division Contraction Secretion All other special functions Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Introduction Nutrient requirements – Vary between any 2 tissues – Changes as metabolic needs change Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Introduction Different organs and tissues store excess nutrients – Example: Lipids in adipose tissue Endocrine system controls the storage and release of nutrients Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Introduction Nutrition – Absorption of nutrients from food Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Metabolism – Refers to all chemical reactions in the body Cellular metabolism – Chemical reactions within cells – Provides energy to maintain homeostasis and perform essential functions Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nutrient pool – Includes all nutrients in the cytoplasm – Includes amino acids, lipids, and simple sugars – Utilized for all the cell’s metabolic operations Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Catabolism – Breakdown of organic molecules – Releases energy Used to synthesize ATP and other high-energy compounds Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Steps in catabolism – Initial steps occur in cytosol Enzymes break down large organic molecules Form smaller fragments Example: Carbohydrates broken down into short carbon chains Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Steps in catabolism – Initial steps Produce very little ATP Products can be absorbed and processed by mitochondria Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Steps in catabolism – Mitochondrial steps Release significant amounts of energy Mitochondrial enzymes break covalent bonds Capture roughly 40% of energy released Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Steps in catabolism – Mitochondrial steps Captured energy Converts ADP to ATP Escapes as heat that warms the interior of the cell and surrounding tissue Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Anabolism – Synthesis of new organic molecules Involves the formation of new chemical bonds Uses the energy produced by mitochondrial processes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Mitochondrial processes – Energy supports anabolism and other functions Ciliary or cell movement Contraction Active transport Cell division Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism 4 reasons for synthesis of new organic components – To perform structural maintenance and repairs – To support growth – To produce secretions – To build nutrient reserves Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism To perform structural maintenance and repairs – Metabolic turnover Continuous removal and replacement of cell structures Most cell structures are temporary Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism To support growth – Enlarge and synthesize extra proteins and organelles – Necessary as cells prepare to divide Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism To produce secretions – Secretory cells synthesize their products – Deliver them to interstitial fluid Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism To build nutrient reserves – Utilized during periods of extreme activity – Utilized when nutrient supply in bloodstream is inadequate – Nutrients mobilized as needed – Example: Glucose stored as glycogen Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nutrient pool – Source of organic molecules – Used for anabolism and catabolism – Conserve materials to build new compounds – Break down remaining compounds Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nutrient pool – Anabolic activities Require more amino acids than lipids and carbohydrates – Catabolic activities Process organic molecules in reverse order Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Mitochondria – Requires specific organic molecules for processing and energy production Chemical reactions occur in cytoplasm Break organic nutrients in the pool into smaller carbon chains Mitochondria use the small carbon chains Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Mitochondria – Chemical reactions continue to break down fragments – Generate carbon dioxide, water, and ATP Involves 2 pathways TCA cycle Electron transport system Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate metabolism – Important sources of energy Sugars and starches Break down to generate ATP and other high-energy compounds Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate metabolism – Chemical reaction C6H12O6 + 6 O2 ↔ 6 CO2 + 6 H2O Glucose + oxygen ↔ carbon dioxide + water Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate metabolism – Occurs in a series of small steps – Releases enough energy to support conversion between ADP and ATP – Completes conversion creates 36 ATP molecules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate metabolism – First steps occur in cytosol Reactions called glycolysis Anaerobic – Most ATP production occurs in the mitochondria Consume oxygen Called aerobic or cellular metabolism Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Glycolysis – Breakdown of glucose to pyruvic acid – C6H12O6 breaks into 2 C3H4O3 (CH3-COCOOH) Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Glycolysis requirements – – – – Glucose molecules Appropriate cytoplasmic enzymes ATP and ADP NAD (nicotinamide adenine dinucleotide) Coenzyme that removes hydrogen atoms Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Glycolysis – Reaction gains 2 ATP for each glucose molecule converted to 2 pyruvic acid molecules Only energy production used by red blood cells Most cells cannot survive on ATP from glycolysis alone Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Glycolysis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy production within mitochondria – Additional energy stored in pyruvic acid bonds – Requires oxygen to liberate energy Mitochondria absorb pyruvic acid Completely break down molecule Hydrogen removed with coenzymes Source of energy gain Carbon and oxygen removed as carbon dioxide Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy production within mitochondria – Mitochondria have 2 membranes Outer membrane permeable to pyruvic acid Inner membrane utilizes a carrier protein Transports pyruvic acid into matrix Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy production within mitochondria – Pyruvic acid participates in reaction – Leads to a series of enzymatic reactions Tricarboxylic acid (TCA) cycle Removes hydrogen from organic molecules Transfers hydrogen to coenzymes in electron transport system Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Involves Pyruvic acid NAD Coenzyme A (CoA) Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Yields: 1 molecule of carbon dioxide 1 molecule of NADH 1 molecule of acetyl-CoA Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Acetyl CoA 2-carbon acetyl group CH3CO Bound to coenzyme A Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Acetyl group transferred from CoA to a 4-carbon molecule – Forms a 6-carbon molecule Citric acid Reaction referred to as the citric acid cycle Also referred to as the Krebs cycle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Citric acid produced – CoA released intact to bind again – Removes 2 added carbon atoms Regenerates the 4-carbon chain Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – 2 carbon atoms Generates 2 carbon dioxide molecules Metabolic waste product Hydrogen atoms of acetyl group Removed by coenzymes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Benefit of 1 revolution Forms a single molecule of guanosine triphosphate (GTP) High-energy compound Readily converted to ATP Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Hydrogen atoms Removed by coenzymes NAD FAD Flavine adenine dinucleotide Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – Coenzymes form: NADH FADH2 – Transfers atoms to the electron transport system Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The Electron Transport System (ETS) – Embedded in the inner mitochondrial membrane – Consists of an electron transport chain Made up of cytochromes Series of protein-pigment complexes – Does not produce ATP directly Creates conditions necessary for ATP production Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – Hydrogen atoms do not enter ETS intact Only electrons enter ETS Protons released into mitochondrial matrix Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – Electron transport from NADH Involves the coenzyme FMN – Electron transport FADH2 Moves directly to coenzyme Q Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – – – – Electrons passed from coenzyme Q Move to the first cytochrome Continue to pass between cytochromes Lose energy in a series of small steps Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – Energy used to drive hydrogen ion pumps Move hydrogen ions from mitochondrial matrix Move into the intermembrane space Located between the 2 mitochondrial membranes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – Creates a large concentration gradient across inner membrane – Hydrogen ions diffuse into the matrix Requires membrane enzyme ATP synthase Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The ETS – Hydrogen ions create kinetic energy Used to attached phosphate group to ADP Forms ATP Process called chemiosmosis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism End of the ETS Oxygen atom accepts the electrons Combines with 2 hydrogen ions Forms water molecule Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism The TCA cycle – ETS Most important mechanism for ATP generation Provides 95% of ATP needed by cells Cells die if ETS stopped by lack of oxygen in mitochondria Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy yield of glycolysis and cellular respiration – Chemical reactions begin with glucose End with carbon dioxide and water Main method of generating ATP Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy yield of glycolysis and cellular respiration – ATP gains During glycolysis in cytoplasm 2 ATP for each glucose molecule converted to pyruvic acid Inside mitochondria Pyruvic acid fully broken down in TCA cycle Each revolution of TCA cycle yields 1 ATP 2 ATP gained Electron transport chain 32 ATP generated for each glucose molecule broken down Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Energy yield of glycolysis and cellular respiration – Total ATP gain 1 glucose molecule processed 36 ATP produced 34 ATP produced inside mitochondria Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Alternate catabolic pathways – Aerobic metabolism Cells require adequate oxygen and glucose supplies Without oxygen Cells survive for brief periods Without glucose Cells break down other nutrients Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Alternate catabolic pathways – Nutrient sources Cells can switch as the need arises Move from glucose to lipids Cells at rest rely on fatty acids Active cells use glucose Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Alternate catabolic pathways – Protein use Only when lipids and carbohydrates not available Enzymes and organelles needed for cell survival Composed of proteins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Alternate catabolic pathways – Nucleic acids Present only in small quantities Seldom catabolized for energy Even when cells die from acute starvation DNA in nucleus determines cells characteristics Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Glycolysis steps not reversible – Glucose cannot be produced using same enzymes Requires different enzymes Independently regulated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Glucose synthesis Uses pyruvic acid or other three-carbon molecules Can be completed from noncarbohydrate precursors Lactic acid, glycerol, or amino acids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Acetyl-CoA Cannot be used Reaction between pyruvic acid and acetyl-CoA not reversible Removes carbon dioxide Called decarboxylation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Gluconeogenesis Synthesis of glucose from noncarbohydrate precursors Cannot use fatty acids and many amino acids Breakdown produces acetylCoA Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Glucose molecules used to manufacture molecules Simple sugars Complex carbohydrates Nucleic acids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Carbohydrate synthesis – Glucose molecules Stored as glycogen in the liver Energy reserve Broken down when cells cannot obtain glucose from interstitial fluid Form compact, insoluble granules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid metabolism – Contain carbon, hydrogen, and oxygen Different proportions than carbohydrates – Triglycerides Most abundant lipid in the body Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Referred to as lipolysis – Lipids broken down Converted to pyruvic acid Can be channeled directly into TCA cycle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Triglycerides Split into component parts by hydrolysis Yields: 1molecule of glycerol 3 fatty acid molecules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Glycerol Converted to pyruvic acid by cytoplasmic enzymes Enters the TCA cycle Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Fatty acid catabolism Referred to as beta-oxidation Reaction with different enzymes Broken down into two-carbon fragments Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Two-carbon fragments Enter TCA cycle Combine to form ketone bodies Short carbon chains Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – Beta-oxidation Occurs inside the mitochondria Two-carbon fragments enter TCA cycle immediately Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid catabolism – ATP generation Break down 118-carbon fatty acid molecule Generates 144 ATP molecules Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipids and energy production – Important energy reserves – Breakdown provides large quantities of ATP – Insoluble in water Stored in compact droplets in cytosol Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipids and energy production – Large droplets Difficult access for water-soluble enzymes Reserves more difficult to access then carbohydrates Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipids and energy production – Processed in mitochondria Activity limited by oxygen availability Cannot provide large amounts of ATP quickly Used when glucose supplies are limited Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid synthesis – Referred to as lipogenesis – Glycerol Synthesized from three-carbon product of glycolysis – Most other lipids Synthesis begins with acetyl-CoA Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid synthesis – Can use almost any organic molecule Can be converted to acetyl-CoA Cannot synthesize everything they can break down Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid synthesis – Essential fatty acids Not synthesized by the body Must be included in diet Used to synthesize prostaglandins and phospholipids Used in the cell membrane Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Lipids needed to maintain cell membranes – Steroid hormones must reach target cells in different tissues – Lipids not soluble in water – Require special mechanisms for transport Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Lipoproteins Lipids circulating in the bloodstream Lipid-protein complexes Contain triglycerides and cholesterol Outer coating of phospholipids and proteins Make complex soluble Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Exposed proteins Bind to specific membrane receptors Determine which cells absorb associated lipids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Classification of lipids Size Relative proportions of lipids and proteins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Chylomicrons Form in the intestinal tract Largest lipoproteins 95% of weight consists of triglycerides Transport to the bloodstream Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Other major groups of lipoproteins Formed in the liver Contain few triglycerides Low-density lipoproteins (LDLs) High-density lipoproteins (HDLs) Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – LDLs Deliver cholesterol to peripheral tissues May end up in arterial plaques Often called “bad cholesterol” Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – HDLs Transport excess cholesterol from peripheral tissues Transported to the liver Stored Excreted in the bile Does not cause circulatory problems Called “good cholesterol” Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Free fatty acids (FFA) Lipids that easily diffuse across the cell membranes Major source is breakdown of fat stored in adipose tissue Released into the blood Bind to albumin Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Lipid transport and distribution – Free fatty acids Important energy source during starvation Can be metabolized by: Liver cells Cardiac muscle cells Skeletal muscle fibers Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Protein metabolism – Body synthesizes over 400,000 proteins Varied forms, functions, and structures Composed of combinations of 20 amino acids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Protein metabolism – Normal conditions Continuous recycling of cellular proteins Occurs in the cytoplasm Peptide bonds are broken Free amino acids used to manufacture new proteins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Protein metabolism – Inadequate energy sources Mitochondria break down amino acids in TCA cycle Generate ATP Benefits vary Yield comparable to carbohydrate catabolism Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – First step Removal of the amino group Requires coenzyme Derived from vitamin B6 Pyridoxine Removed by transamination or deamination Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Transamination Attaches amino group to another carbon chain Creates a new amino acid Enables the cell to synthesize many amino acids for protein synthesis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Transamination Locations Liver Skeletal muscles Heart Lung Kidney Brain Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Deamination Prepares amino acid for breakdown in TCA cycle Removes the amino group Generates an ammonia molecule (NH3) Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Deamination Ammonia Highly toxic in low concentrations Production occurs in the liver Enzymes combine ammonia with carbon dioxide Produces urea Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Deamination Carbon chain remains Can be converted to pyruvic acid Used in gluconeogenesis Can be converted to acetyl-CoA Broken down in TCA cycle Can be converted to ketone bodies Organic acid like acetone Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Ketone bodies Diffuse into general circulation Not metabolized by the liver Reconverted into acetyl-CoA Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acid catabolism – Ketosis High concentration of ketone bodies in body fluids Increased production of ketone bodies Occurs during protein and lipid catabolism Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Protein catabolism – Impractical source of quick energy More difficult to break apart than complex carbohydrates or lipids Ammonia is toxic to the cells Extensive catabolism threatens homeostasis at cellular and systems levels Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acids and protein synthesis – 10 essential amino acids 8 cannot be synthesized Isoleucine Leucine Lysine Threonine Tryptophan Phenylalanine Valine Methionine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acids and protein synthesis – 2 essential amino acids can be synthesized Amounts are insubstantial for growing children Arginine Histidine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acids and protein synthesis – Nonessential amino acids Can be synthesized on demand Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acids and protein synthesis – Protein deficiency diseases Develop with inadequate consumption of essential amino acids All amino acids must be present for protein synthesis to occur Transfer RNA molecule must appear at the proper time If it does not, process is halted Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Amino acids and protein synthesis – Inherited metabolic disorders Result from an inability to produce specific enzymes Involved in amino acid metabolism Phenylketonuria (PKU) Cannot convert specific amino acid due to an enzyme defect Essential in the synthesis of NE, E, and melanin CNS development inhibited resulting in severe brain damage Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nucleic acid metabolism – Living cells contain both DNA and RNA – DNA essential in long-term cell survival Never catabolized for energy, even when dying of starvation – RNA involved in protein synthesis Broken down and replaced regularly Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism RNA catabolism – Molecule disassembled into individual nucleotides Most recycled into new nucleic acids Can be broken down to simple sugars and nitrogen bases Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism RNA catabolism – Generation of ATP Only cytosine and uracil can enter TCA cycle Adenine and guanine cannot be catabolized Undergo deamination Excreted as uric acid Nitrogenous waste Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism RNA catabolism – Hyperuricemia Elevated level of uric acid Saturates body fluids Symptoms do not appear immediately May begin to form crystals Develops into gout Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nucleic acid synthesis – RNA synthesis Occurs in most cells – DNA synthesis Occurs only in cells preparing for mitosis or meiosis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nucleic acid synthesis – RNA polymerase Enzyme that transcribes different forms of RNA Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA) Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nucleic acid synthesis – Messenger RNA Manufactured as needed When specific genes are activated Has a life span measured in minutes to hours – Ribosomal RNA Lasts just over 5 days Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Cellular Metabolism Nucleic acid synthesis – Typical cell 100,000 ribosomes Many times more tRNA molecules Replacement involves great deal of synthetic activity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Maintenance of homeostasis – Continues indefinitely Digestive tract absorption must keep pace with cellular demands Nutrition is the absorption of essential nutrients form food Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Nutrient requirements – Varies from day to day Person to person – Nutritionists Analyze diet’s ability to prevent and treat illnesses Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Balanced diet – Contains all nutrients needed to maintain homeostasis Adequate substrates for generating energy Essential amino acids Fatty acids, minerals, and vitamins Water Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – 5 basic food groups Grains Vegetables Fruits Milk Meat and beans Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – Food groups Vary in protein, carbohydrate, and lipid content Vary in amounts and types of vitamins and minerals Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – Food pyramid 6 groups 5 basic food groups Fats, sugars, and salt category Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – Food pyramid 6 bands Different colors and widths Width is a guide to daily recommended consumption Stairs on the side Stress daily physical activity and weight control Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – Proper nutrition Sufficient quantity Adequate quality Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Food groups and the food pyramid – Complete proteins Animal proteins Contain all essential amino acids in sufficient quantities – Incomplete proteins Plants Contain adequate amounts of proteins Deficient in one or more essential amino acids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals, vitamins, and water – Essential components of the diet – Body cannot synthesize minerals – Cells generate only small quantities of water and very few vitamins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals – Inorganic ions – Released through the dissociation of electrolytes Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals – Ions such as sodium and chloride determine the osmotic concentration of body fluids Potassium important in maintaining osmotic concentration inside cells Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals – Ions in various combinations play major roles in important physiological processes Maintenance of membrane potentials Construction and maintenance of the skeleton Action potential generation Neurotransmitter release Transport of gasses Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals – Ions are essential cofactors in a variety of enzymatic reactions Example: Enzyme responsible for breakdown of ATP in contracting skeletal muscles Requires calcium and magnesium ions Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Minerals – Reserves Significant for several important minerals Reduce effects of dietary variations Chronic deficiencies lead to clinical problems Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Vitamins – Essential organic nutrients – Related to lipids and carbohydrates – 2 groups Fat-soluble Water-soluble Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Fat-soluble vitamins – A, D, E, and K – Absorbed primarily from the digestive tract With the lipid contents of micelles Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Fat-soluble vitamins – Vitamin D A group of steroid-like molecules Includes vitamin D3 or cholecalciferol Can be synthesized in adequate amounts Requires exposure of skin to sunlight Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Fat-soluble vitamins – Dissolve in lipids Allows diffusion into cell membranes Body can contain significant reserves Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Fat-soluble vitamins – Avitaminosis Vitamin deficiency disease Rarely results from dietary insufficiency Caused by inability to absorb vitamins, inadequate storage, or excessive demand Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Fat-soluble vitamins – Hypervitaminosis Dietary intake exceeds ability to store, utilize, or excrete Usually involves fat-soluble vitamins as they are stored in body lipids Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water-soluble vitamins – Most are components of coenzymes Example: NAD derived from niacin, CoA from vitamin B3 – Rapidly exchanged between the digestive tract and circulating blood – Excesses are readily excreted in the urine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water-soluble vitamins – Intestinal bacteria Help prevent deficiency diseases Produce 5 of the 9 water-soluble vitamins Also produce vitamin K Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water-soluble vitamins – Intestinal epithelium Readily absorb all water-soluble vitamins Except vitamin B12 Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water-soluble vitamins – Vitamin B12 Large molecule Must bind to intrinsic factor before absorption Secreted by the gastric mucosa Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water – Daily requirement Roughly 2500 ml or 40 ml/kg Varies with environment and metabolic activities Example: 1°C fever increases water loss by 200 ml Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Water – Daily requirements Most obtained through eating and drinking Small amount produced in mitochondria Electron transport system Called metabolic water Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Diet and Nutrition Diet and disease – Long-term problems Caused by elevated calorie intake Elevated proportion of lipids Increases the incidence of obesity, heart disease, HTN, DM Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics How organisms acquire and use energy – Chemical bonds are broken – Energy is released Some energy is captured as ATP Most lost as heat Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Calorie (cal) – Unit of energy measurement Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Kilocalorie (kcal) – Calorie (Cal) – Amount of energy required to raise the temperature of 1 kg of water 1ºC – Designation used in calorie-counting guides Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics The energy content of food – Organic molecules combine with oxygen – Broken down to carbon dioxide and water – Oxygen also consumed when something burns Combustion can be observed and measured Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics The energy content of food – Measurement Known amount of food is placed into a container Calorimeter Filled with oxygen and surrounded by a known amount of water Chamber is sealed Contents ignited electrically Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics The energy content of food – Measurement Food completely burned Only ash remains Compare water temperature before and after Determines calories released Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics The energy content of food – Catabolism of foods Lipids 9.46 cal/g Carbohydrates 4.18 cal/g Proteins 4.32 cal/g Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Metabolic rate – Sum of all various anabolic and catabolic processes occurring in the body – Varies with activity Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Basal metabolic rate (BMR) – Standardized testing conditions – Reflects minimum resting energy expenditures of an awake, alert person – Average is 70 cal/hr or 1680 cal/day Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Basal metabolic rate – Influential factors Age Sex Physical condition Body weight Genetic differences Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Metabolic rate – If intake exceeds energy demand Excess stored, primarily as triglycerides in adipose tissue – If expenditures exceed intake Energy reserves reduced, resulting in weight loss Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Thermoregulation – BMR Estimate of the rate of energy use Body cells capture only a part of that energy Remaining is lost as heat Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Thermoregulation – Homeostatic process – Anatomical and physiological mechanisms control body temperature Regardless of environmental conditions – Temperature control necessary as enzymes require a narrow temperature range to function Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Mechanisms of heat transfer – 4 basic processes Radiation Conduction Convection Evaporation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Mechanisms of heat transfer Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Radiation – Warm objects lose heat as infrared heat energy – Accounts for more than half of the heat lost Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Conduction – Direct transfer of energy through physical contact – Not an effective method of gaining or losing heat Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Convection – Result of conductive heat loss to air that overlies the surface of an object – Warm air rises, moving away from the skin – Cool air replaces it, again warming Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Evaporation – Water changes from a liquid to a vapor – Process absorbs energy 580 calories per gram of water – Cools any surface on which it occurs Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Evaporation – Insensible perspiration Evaporation from the alveolar surfaces of the lungs and skin surface 20–25 ml/hr – Sensible perspiration Sweat glands Can range from nothing up to 2–4 l/hr Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Mechanisms of heat transfer – Maintaining homeostasis Heat loss must equal heat gain Coordinated by the hypothalamus Heat-loss center Heat-gain center Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Mechanisms of heat transfer – Heat-loss center Makes adjustments through parasympathetic division of ANS – Heat-gain center Makes adjustments through sympathetic division of ANS Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat loss – Temperature at heat-loss center exceeds set point Triggers 3 responses Peripheral blood vessels dilate Sweat glands stimulated Respiratory centers stimulated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat loss – Dilation of peripheral vessels Sends warm blood to the surface of the body Skin becomes red Skin temperature rises Heat loss through radiation and convection increases Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat loss – Stimulation of sweat glands Perspiration flows across the skin Accelerates heat loss through evaporation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat loss – Stimulation of respiratory centers Depth of respiration increases Enhances heat loss through evaporation from the lungs Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat loss – Heat loss by evaporation Efficiency varies with environmental conditions Increased humidity decreases effectiveness of evaporation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat gain: heat conservation and generation – Heat-gain center of the brain Prevents hypothermia Activation promotes heat conservation and generation Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat gain: heat conservation and generation – Heat conservation Decreased blood flow to the skin Reduces heat loss through radiation, convection, and conduction Skin may become bluish or pale Blood is shunted to deep veins Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Promoting heat gain: heat conservation and generation – 2 mechanisms for heat generation Shivering thermogenesis Nonshivering thermogenesis Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Shivering thermogenesis – Muscle tone gradually increased – Stretch receptors stimulate brief, oscillatory contractions of antagonistic skeletal muscles – Shivering stimulates energy consumption by skeletal muscles – Generated heat warms deep vessels Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Nonshivering thermogenesis – Hormones released Increase metabolic activity of cells in all tissues Epinephrine Increases breakdown of glycogen and glycolysis Increases metabolic rate Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Bioenergetics Nonshivering thermogenesis – Heat-gain center stimulates release of thyroxine Accelerates carbohydrate use Accelerates the breakdown of all other nutrients Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Nutritional requirements do not change drastically with age Other changes directly affect nutrition and health – Lifestyle changes – Eating habits – Income Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Caloric requirements change with aging – Proportions of calories by different food groups do not – Caloric requirement reduces 10% for each decade over 50 Associated with reductions in metabolic rates, body mass, activity, and exercise Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Increased need for calcium – Osteoporosis is a normal consequence of aging Sedentary lifestyle increases the problem – Rate of bone loss decreases if calcium levels remain elevated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Require supplemental vitamin D3 for calcium absorption – Remaining indoors eliminates production by the skin – Vitamin converted to calcitrol Stimulates calcium absorption in the small intestine Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Olfactory and gustatory receptor sensitivity decreases with age – Food becomes less appetizing – Less food is eaten Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Aging and Nutritional Requirements Digestion and absorption – Mucosal lining of digestive tract Becomes thinner Nutrient absorption is less efficient Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ Summary Describe and understand the components of glycolysis, the TCA cycle, and ETS Describe how materials are metabolized Describe the types and functions of nutrients Understand how temperature is regulated Bledsoe et al., Anatomy & Physiology for Emergency Care, 2nd Ed. © 2008 by Pearson Education, Inc. Upper Saddle River, NJ