Download 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