Transcript Ch.21
PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Tenth Edition Shier w Butler w Lewis Chapter 21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 21-1 Chapter 21 Water, Electrolyte, and Acid-Base Balance Of the 40 liters of water in the body of an average adult male, about two-thirds is intracellular, and one-third is extracellular 21-2 Fluid Compartments 21-3 Body Fluid Composition 21-4 Movement of Fluids Between Compartments Net movements of fluids between compartments result from differences in hydrostatic and osmotic pressures 21-5 Water Balance • urine production is most important in the regulation of water balance 21-6 Regulation of Water Intake • increase in osmotic pressure of extracellular fluid stimulates osmoreceptors in thirst center • person feels thirsty • drinking and distension of the stomach by water stimulate nerve impulses that inhibit thirst center • water is absorbed • osmotic pressure of extracellular fluid returns to normal 21-7 Regulation of Water Output Dehydration • osmotic pressure increases in extracellular fluids • osmoreceptors in hypothalamus stimulated • hypothalamus signals posterior pituitary to release ADH • urine output decreases Excess Water Intake • osmotic pressure decreases in extracellular fluids • osmoreceptors stimulated in hypothalamus • hypothalamus signals posterior pituitary to decrease ADH output • urine output increases 21-8 Electrolyte Balance 21-9 Potassium and Sodium Balance 21-10 Calcium Balance 21-11 Sources of Hydrogen Ions • aerobic respiration of glucose produces carbonic acid • anaerobic respiration of glucose produces lactic acid • incomplete oxidation of fatty acids produces acidic ketone bodies • oxidation of amino acids containing sulfur produces sulfuric acid • breakdown of phosphoproteins and nucleic acids produces phosphoric acid • some hydrogen ions are absorbed through digestive tract 21-12 Strengths of Acids and Bases • Strong acids ionize more completely and release more H+ • Weak acids ionize less completely and release fewer H+ • Strong bases ionize more completely and release more OH- • Weak bases ionize less completely and release fewer OH- 21-13 Regulation of Hydrogen Ion Concentration • acid-base buffer systems • respiratory excretion of carbon dioxide • renal excretion of hydrogen ions 21-14 Acid-Base Buffer Systems Bicarbonate System • the bicarbonate ion converts a strong acid to a weak acid • carbonic acid converts a strong base to a weak base H+ + HCO3- H2CO3 H+ + HCO3Phosphate System • the monohydrogen phosphate ion converts a strong acid to a weak acid • the dihydrogen phosphate ion converts a strong base to a weak base H+ + HPO4-2 H2PO4- H+ + HPO4-2 21-15 Acid-Base Buffer Systems Protein Buffer System • NH3+ group releases hydrogen ions in the presence of excess base • COO- group accepts hydrogen ions in the presence of excess acid 21-16 Respiratory Excretion of Carbon Dioxide 21-17 Renal Excretion of Hydrogen Ions 21-18 Summary of Acid-Base Balance 21-19 Clinical Application Acid-Base Imbalances If the pH of arterial blood drops to 6.8 or rises to 8.0 for more than a few hours, the person usually cannot survive acidosis versus alkalosis factors that lead to respiratory acidosis 21-20 Clinical Application Metabolic acidosis Respiratory alkalosis Metabolic alkalosis 21-21