1 Fluid, Electrolyte, and Acid-Base Balance

2 Fluid Picture here salvador dali

3 Fluid Solution is a mixtureSolvent Solution is a mixture Most abundant component in a solution is the solvent. Other components are solutes. Solutions are good for delivering food, removing waste. Examples include blood, urine, intracellular fluid, interstitial fluid, etc. Solute Picture of solution/solvent from ap1cells

4 Water The most important biological solvent is water.Healthy males are about 60% water; healthy females are around 50% Infants have low body fat, low bone mass, and are 73% or more water Total water content declines throughout life In old age, only about 45% of body weight is water This difference reflects females’: Higher body fat Smaller amount of skeletal muscle

5 The solvent is always water but that leaves three questions?What solutions are there? Intracellular fluid Interstitial fluid Blood plasma 2. What solutes are there? Electrolytes Non-Electrolytes 3. How much solute is in the solution (concentration)? Moles/Liter mEq

6 Fluid Compartments in the BodyYou can divide your body into two compartments, intracellular fluid and extracellular fluid. Its more complete to think of your body as divided into three solution-filled compartments. Intracellular fluid Interstitial fluid Blood plasma

7 Fluid Compartments Intracellular fluid (ICF) – about two thirds by volume, contained in cells 1 gallon = .26 liters Interstitial fluid (IF) – fluid in spaces between cells Plasma the fluid portion of the blood

8 Edema is accumulation of fluid in the ____________.Special fluid compartments Interstitial space Intracellular space Plasma All of the above.

9 Extracellular and Intracellular FluidsExtracellular fluids are similar (except for the high protein content of plasma) Sodium is the chief cation Chloride is the major anion Intracellular fluids have low sodium and chloride Potassium is the chief cation Phosphate is the chief anion Na+ Na+ Cl- Cl- HPO4- Cl- K+ K+ Each fluid compartment of the body has a distinctive pattern of electrolytes HPO4- K+ HPO4- K+ K+ HPO4- Na+ Na+ Cl- Na+

10 Extracellular and Intracellular FluidsOutside Cell Inside Cell Outside Cell Inside Cell Sodium and potassium concentrations in extra- and intracellular fluids are nearly opposites This reflects the activity of cellular ATP-dependent sodium-potassium pumps

11 Electrolyte Comp. of Body Fluids

12 The solvent is always water but that leaves three questions?What solutions are there? Intracellular fluid Interstitial fluid Blood plasma 2. What solutes are there? Electrolytes Non-Electrolytes 3. How much solute is in the solution (concentration)? Moles/Liter mEq

13 Composition of Body FluidsSolutes can be either electrolytes or nonelectrolytes. Electrolytes = charged molecules inorganic salts, all acids and bases, and some proteins Nonelectrolytes = uncharged molecules examples include glucose, lipids, creatinine, and urea PICTURES All solutes can move water. But, electrolytes are much more powerful at it

14 Osmosis The movement of water to follow solutes Isotonic HypotonicHypertonic

15 Electrolytes Electrolytes have greater osmotic power than nonelectrolytes due to charge. Ions can use charge to sense/influence over a large distance.

16 The solvent is always water but that leaves three questions?What solutions are there? Intracellular fluid Interstitial fluid Blood plasma 2. What solutes are there? Electrolytes Non-Electrolytes 3. How much solute is in the solution (concentration)? Moles/Liter mEq

17 Concentration Understanding concentration is important because “the dose makes the poison.” The speed, and effectiveness of hormones, drugs, poisons and other chemicals is dependent on concentration. In general, if you double the concentration of something, you double its rate of reaction. AB  A + B

18 Concentration of SolutesConcentration may be expressed in several ways but essentially the amount per given volume. Moles/liter Milliequivalents per liter (mEq/L), a measure of the number of electrical charges in one liter of solution mEq/L = (concentration of ion in [mg/L]/the atomic weight of ion)  number of electrical charges on one ion

19 Electrolyte ConcentrationExpressed in milliequivalents per liter (mEq/L), a measure of the number of electrical charges in one liter of solution mEq/L = (concentration of ion in [mg/L]/the atomic weight of ion)  number of electrical charges on one ion For single charged ions, 1 mEq = 1 mOsm For bivalent ions, 1 mEq = 1/2 mOsm It takes half as many Ca++ as Na+ to make 1 mEq because Ca++ has two charges

20 Transition

21 Fluid Movement Among Compartments

22 Water Balance and ECF OsmolalityTo remain properly hydrated, water intake must equal water output Water intake sources Ingested fluid (60%) and solid food (30%) Metabolic water or water of oxidation (10%) Water output Urine (60%) and feces (4%) Insensible losses (28%), sweat (8%) Metabolic water, taking water out of things to make them solid; dehydrolysis reactions

23 Fluid Movement Among CompartmentsWater intake sources Ingested fluid (60%) and solid food (30%) Metabolic water or water of oxidation (10%) Water output Urine (60%) and feces (4%) Insensible losses (28%), sweat (8%) Outputs Intake Sources Fluids 1540 ml Food 660 ml

24 Water Intake and Output

25 Water Disturbances You can have two types of water disturbances.Too much or too little pure water Will affect ion concentrations and thus a number of things such as excitability of neurons, muscles, and the heart. Too much or too little isotonic fluid (water plus salt). Mainly affects blood pressure.

26 Disturbances of Water Homeostasiswater and solute water Too much Hypervolemia Overhydration Too little Hypovolemia Dehydration

27 Disturbances of Water Homeostasis: Sample Causeswater and solute water Too much IV errors Water retention High salt diet Cell damage Excessive drinking Too little Blood loss Fluid loss Sweating diarrhea

28 Disturbances of Water Homeostasis: Sample Effectswater and solute water Too much High blood pressure Dilutes solutes Arrythmias CNS dysfunction Too little Low blood pressure Concentrates solutes

29 Disturbances of Water Homeostasis: Sample Solutionswater and solute water Too much Inhibit aldosterone Inhibit ADH ANP Sympathetic Too little Aldosterone ADH Thirst Angiotensin thirst

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31 Fluid Homeostasis There are basically six mechanisms to regulate fluid homeostasis. Anti-Diuretic Hormone (ADH) Thirst Renin-Angiotensin-Aldosterone System Sympathetic Nervous System Atrial Natriuretic Protein (ANP) Increased GFR

32 1. Influence and Regulation of ADHADH is released by the posterior pituitary in response to osmoreceptors sensing concentrated plasma. ADH inserts water channels in the collecting duct Low ADH increase urine and decrease fluid volume High ADH levels decrease urine and conserve

33 Permeability of H20 is controlled by ADHNo ADH Permeability of H20 is controlled by ADH

34 Which factor would increase the secretion of ADH?Increased renal blood flow Thirst Excess salt consumption Hypotonic ECF concentration Ethanol consumption

35 All of the following statements about ADH are true except:The amount of water lost in the urine is inversely proportional to the amount of ADH released. ADH decreases the volume of urine and dilutes urine. In the absence of ADH, there is a lack of channels to allow water to escape the collecing duct. A decrease in blood pressure would cause an increase in ADH release.

36 Mechanisms and Consequences of ADH Release

37 2. Thirst The hypothalamus controls thirstThe hypothalamic thirst center is stimulated: By a decline in plasma volume of 10%–15% By increases in plasma osmolality of 1–2% Via baroreceptor input, angiotensin II, and other stimuli How could a neuron sense increased Na+ concentration?

38 2. Thirst Thirst is quenched as soon as we begin to drink waterFeedback signals that inhibit the thirst centers include: Moistening of the mucosa of the mouth and throat Activation of stomach and intestinal stretch receptors

39 Regulation of Water Intake: Thirst Mechanism

40 3. Renin-Angiotensin MechanismIs triggered when the JG cells release renin Renin acts on angiotensinogen (liver) to release angiotensin I Angiotensin I is converted to angiotensin II by ACE (capillaries) Angiotensin II goes to adrenal cortex Aldosterone is released Causes mean arterial pressure to rise Stimulates the adrenal cortex to release aldosterone Increase Na+ absorption in DCT/CD As a result, both systemic and glomerular hydrostatic pressure rise

41 Juxtaglomerular Apparatus (JGA)Distal Tubule comes back up near glomerulus

42 Renin-Angiotensin MechanismCollecting Duct

43 In response to increased levels of aldosterone, the kidneys produceUrine with a lower concentration of sodium ions. Urine with a lower concentration of potassium ions. A larger volume of urine. Urine with a lower specific gravity. Urine with less urea.

44 4. Sympathetic Nervous SystemDecreased blood pressure stimulates the sympathetic nervous system. Sympathetic nervous system can control the afferent arteriole and thus constricts it. Decrease GFR = less water loss = increase in bp Constricts

45 5. Atrial Natriuretic Peptide (ANP)Reduces blood pressure and blood volume by inhibiting: Events that promote vasoconstriction Na+ and water retention Is released in the heart atria as a response to stretch (elevated blood pressure) Inhibits angiotensin II production Promotes excretion of sodium and water

46 Which of the following statements about the atrial natriuretic peptide (ANP) are incorrect?It suppresses the release of renin and aldosterone. It reduces blood pressure and inhibits vasoconstriction. It is released in response to stretching certain cells in the heart. It acts as a potent diuretic but does not affect Na+ levels in the body.

47 6. Glomerular filtrationExcess fluid results in higher pressures in the glomerulus Equals higher GFR and loss of fluid into urine Which decreases fluid volume Too little fluid results in lower pressures in the glomerulus Equals lower GFR and retention of fluid Which increases fluid volume

48 When large amounts of pure water are consumedA fluid shift occurs and the volume of the ICF decreases. The volume of the ICF will increase due to osmosis. The volume of the ECF will decrease. The ECF becomes hypertonic to the ICF. Osmolarities of the two compartments will be slightly lower.

49 When water is lost from the ECF but electrolytes are retained,Osmosis moves water from the ICF to the ECF. Water levels remain homeostatic. The osmolarity of the ECF falls. There is an increase in the volume in the ICF. Both ECF and ICF become more dilute.

50 Physiology adjustments of water and electrolytes are made byAldosterone. Atrial natriuretic peptide. ADH. None of the above All of the above.

51 Transition

53 Disorders of Water Balance: EdemaFour main causes of edema are Increased blood pressure Incompetent venous valves, localized blood vessel blockage Congestive heart failure, hypertension, high blood volume Capillary permeability due to injury Decreased osmotic pressure: decreased albumin production by diseased liver Lymphatic obstruction

54 Capillaries 2. Capillary permeability due to injury: Fluid leaks out of capillary 4. Lymphatic obstruction: if lymph cannot drain, fluid backs up Increased blood pressure increases pressure on fluid to leave capillary 3. Decreased osmotic pressure: no proteins means fluid cannot be pulled back into capillary via osmosis

55 All of the following would cause edema except:Hypotension Hypoproteinemia Liver disease Incompetent venous valves

56 Electrolytes

57 Electrolyte balance in the body usually refers to the balance of _________.Salts Organic molecules Acids Bases

58 The most prevalent electrolyte in the extracellular fluid isPotassium. Magnesium. Phosphate. Sodium. Chloride. Calcium.

59 Electrolytes act as… Co-factors: assist a molecule in getting in the right shape (Fe in hemoglobin) Conduct electricity: Action potential Secretion/release of neurotransmitters Muscle contraction Acid/base balance Transport: (Na+ helps transport glucose, etc.)

60 Cations and Anions Electrolytes are referred to by their charge.Cations are positively charged Na+ K+ Ca2+ Mg2+ Anions are negatively charged. Cl-, Bicarbonate, Phosphate, Sulfate, Proteins, Lactate,

61 Electrolytes Small deviations in electrolyte concentration have serious life-threatening consequences. The three most important ions are Na+, K+, Ca2+.

62 Electrolytes The three most important ions are Na+, K+, Ca2+.Four things to keep in mind with these electrolytes. What are the imbalances called What causes the imbalances What are the results of the imbalances How does the body correct the imbalance.

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66 Capital punishment usually employs KCl injectionCapital punishment usually employs KCl injection. Why would this kind of an injection cause death? Increased K+ causes hyperpolarization of membranes. Hyperkalemia results in acidosis which is lethal. Hypokalemia causes dehydration. Increased K+ results in disruption of the electric potential of cardiac tissue.

67 The amount of Na+ excreted by the kidneys should be…Near Zero The same as consumed in the diet More than is consumed in the diet. An amount always equivalent to K+ losses.

68 The next 16 slides (54-70) that lead up to pH came with the textbook and they may clarify the electrolyte homeostasis charts. But, your main source of info should be the electrolyte charts.

69 Sodium in Fluid and Electrolyte BalanceSodium holds a central position in fluid and electrolyte balance Sodium salts: Account for 90-95% of all solutes in the ECF Contribute 280 mOsm of the total 300 mOsm ECF solute concentration Sodium is the single most abundant cation in the ECF Sodium is the only cation exerting significant osmotic pressure

70 Sodium in Fluid and Electrolyte BalanceChanges in plasma sodium levels affect: Plasma volume, blood pressure ICF and interstitial fluid volumes Renal reabsorption is coupled to sodium ion transport No sodium = diminished renal function urine blood Na+ K+ H20 Other

71 Regulation of Sodium Balance: AldosteroneSodium reabsorption is controlled by aldosterone When aldosterone levels are high, all remaining Na+ is actively reabsorbed Water follows sodium if tubule permeability has been increased with ADH Note the relationship between ADH and aldosterone.

72 Regulation of Sodium Balance: AldosteroneNote the relationship between ADH and aldosterone. Aldosterone moves Na+ ADH moves water The two usually work together but not always. Dehydration stimulates _______ Hypovolemia stimulates _______

73 Regulation of Sodium Balance: AldosteroneNote the relationship between ADH and aldosterone. Aldosterone moves Na+ ADH moves water The two usually work together but not always. Dehydration stimulates __Aldosterone__ Hypovolemia stimulates _Both___

74 Regulation of Sodium Balance: Aldosterone

75 Cardiovascular System BaroreceptorsBaroreceptors alert the brain of increases in blood volume (hence increased blood pressure) Sympathetic nervous system impulses to the kidneys decline Afferent arterioles dilate Glomerular filtration rate rises Sodium and water output increase

76 Cardiovascular System BaroreceptorsThis phenomenon, called pressure diuresis, decreases blood pressure Drops in systemic blood pressure lead to opposite actions and systemic blood pressure increases Since sodium ion concentration determines fluid volume, baroreceptors can be viewed as “sodium receptors”

77 Maintenance of Blood Pressure Homeostasis

78 Atrial Natriuretic Peptide (ANP)Reduces blood pressure and blood volume by inhibiting: Events that promote vasoconstriction Na+ and water retention Is released in the heart atria as a response to stretch (elevated blood pressure) Promotes excretion of sodium and water Inhibits angiotensin II production

79 Mechanisms and Consequences of ANP Release

80 Influence of Other Hormones on Sodium BalanceEstrogens: Enhance NaCl reabsorption by renal tubules May cause water retention during menstrual cycles Are responsible for edema during pregnancy

81 Regulation of Potassium BalanceRelative ICF-ECF potassium ion concentration affects a cell’s resting membrane potential Excessive ECF potassium decreases membrane potential Too little K+ causes hyperpolarization and nonresponsiveness

82 Regulation of Potassium BalanceHyperkalemia and hypokalemia can: Disrupt electrical conduction in the heart Lead to sudden death Hydrogen ions shift in and out of cells Leads to corresponding shifts in potassium in the opposite direction Interferes with activity of excitable cells

83 Regulatory Site: Cortical Collecting DuctsK+ balance is controlled in the cortical collecting ducts by changing the amount of potassium secreted into filtrate

84 Regulation of Calcium Ionic calcium in ECF is important for:Blood clotting Cell membrane permeability Secretory behavior Hypocalcemia: Increases excitability Causes muscle tetany

85 Regulation of Calcium Hypercalcemia:Inhibits neurons and muscle cells May cause heart arrhythmias Calcium balance is controlled by parathyroid hormone (PTH) and calcitonin

86 Acid-Base Balance

87 Acids and Bases Acid/Base is essentially the quantity of H+ (protons) and OH– (hydroxy) floating in the solution. We care about H+ and OH– because they bind to proteins and change their shape, usually diminishing their function. They affect K+ homeostasis They affect Ca2+ homeostasis

88 Acids and Bases So many things in your body will react with H and OH.An H+ could bind to this H and O and create water. This would change the shape of this protein So many things in your body will react with H and OH. When they react, their shape is changed. These change in shapes can change how things work

89 K+ and H+ Flow in Opposite Directions Across the PMAnother reason to be concerned about H+ is that it exchanges with K+ across the plasma membrane. High H+ causes K+ to leave the cell Low H+ causes K+ to enter the cell H+ H+ H+ K+ K+ K+ H+ K+ K+ K+ K+ H+ Interaction of acidosis and increased extracellular potassium on action potential characteristics and conduction in guinea pig ventricular muscle Y Kagiyama, JL Hill and LS Gettes We studied the individual and combined effects of extracellular acidosis and increases in extracellular potassium on action potential characteristics and conduction in order to gain a better understanding of the effects of acute ischemia. At each level of potassium between 2.7 and 17 mm, acidosis induced by increasing Pco2 (respiratory acidosis) and by decreasing HCO3- (metabolic acidosis) decreased resting membrane potential, the maximum rate of rise of the action potential upstroke (Vmax), and slowed conduction. Metabolic acidosis consistently and significantly lengthened the steady state action potential duration whereas respiratory acidosis did not. Respiratory acidosis caused changes in resting membrane potential, Vmax, and conduction velocity; which occurred more rapidly and were of greater magnitude than the changes induced by metabolic acidosis. The changes in Vmax induced both types of acidosis were due to a change in the resting membrane potential-Vmax relationship as well as to the changes in the resting membrane potential. The conduction slowing induced by acidosis was greater when potassium was 9 and 13 mM than when potassium was 5.4 mm. Our results suggest that acidosis causes important changes in the electrophysiological properties of ventricular fibers and that many of the known electrophysiological effects of acute ischemia can be mimicked by the combined effects of extracellular acidosis and an increase in extracellular potassium. K+ H+ H+

91 K+ and H+ Flow in Opposite Directions Across the PMAnother reason to be concerned about H+ is that it exchanges with K+ across the plasma membrane. So disorders of acid become disorders of K+. H+ H+ H+ K+ K+ K+ H+ K+ K+ K+ K+ H+ Interaction of acidosis and increased extracellular potassium on action potential characteristics and conduction in guinea pig ventricular muscle Y Kagiyama, JL Hill and LS Gettes We studied the individual and combined effects of extracellular acidosis and increases in extracellular potassium on action potential characteristics and conduction in order to gain a better understanding of the effects of acute ischemia. At each level of potassium between 2.7 and 17 mm, acidosis induced by increasing Pco2 (respiratory acidosis) and by decreasing HCO3- (metabolic acidosis) decreased resting membrane potential, the maximum rate of rise of the action potential upstroke (Vmax), and slowed conduction. Metabolic acidosis consistently and significantly lengthened the steady state action potential duration whereas respiratory acidosis did not. Respiratory acidosis caused changes in resting membrane potential, Vmax, and conduction velocity; which occurred more rapidly and were of greater magnitude than the changes induced by metabolic acidosis. The changes in Vmax induced both types of acidosis were due to a change in the resting membrane potential-Vmax relationship as well as to the changes in the resting membrane potential. The conduction slowing induced by acidosis was greater when potassium was 9 and 13 mM than when potassium was 5.4 mm. Our results suggest that acidosis causes important changes in the electrophysiological properties of ventricular fibers and that many of the known electrophysiological effects of acute ischemia can be mimicked by the combined effects of extracellular acidosis and an increase in extracellular potassium. K+ H+ H+

92 Acid and Calcium H+ and Ca2+ exchange on albumin.High H+ means High Ca2+ Low H+ means Low Ca2+

93 Acids and Bases Acids release H+ and are therefore proton donorsHCl  H+ + Cl – Bases release OH– and are proton acceptors NaOH  Na+ + OH–

94 Acid-Base Balance Normal pH of body fluidsArterial blood is 7.4 Venous blood and interstitial fluid is 7.35 Intracellular fluid is 7.0 Alkalosis– arterial blood pH rises above 7.45 Acidosis arterial pH drops below 7.35 (physiological acidosis)

95 Acid-Base Concentration (pH)Acidic: pH 0–6.99 Basic: pH 7.01–14 Neutral: pH 7.00 *note this is a log scale

96 Sources of Hydrogen IonsMost hydrogen ions originate from cellular metabolism Breakdown of phosphorus-containing proteins releases phosphoric acid into the ECF Anaerobic respiration of glucose produces lactic acid Fat metabolism yields organic acids and ketone bodies Transporting carbon dioxide as bicarbonate releases hydrogen ions

97 Hydrogen Ion RegulationConcentration of hydrogen ion is regulated sequentially by: Chemical buffer systems – act within seconds The respiratory center in the brain stem – acts within 1-3 minutes Renal mechanisms – require hours to days to effect pH changes

98 Chemical Buffer SystemsThree major chemical buffer systems Bicarbonate buffer system The most important as it feeds into both respiratory and renal acid regulatory systems. Phosphate buffer system Protein buffer system

99 Bicarbonate Buffer SystemHigh base = high pH H2CO3  H+ + HCO3¯ When blood pH rises, carbonic acid dissociates to form bicarbonate and H+ When blood pH drops, bicarbonate binds H+ to form carbonic acid Carbonic acid Bicarbonate High Acid = low pH OH

100 Phosphate Buffer SystemNearly identical to the bicarbonate system Its components are: Sodium salts of dihydrogen phosphate (H2PO4¯), a weak acid Monohydrogen phosphate (HPO42¯), a weak base This system is an effective buffer in urine and intracellular fluid

101 Protein Buffer System Plasma and intracellular proteins are the body’s most plentiful and powerful buffers Some amino acids of proteins have: Free organic acid groups (weak acids) Groups that act as weak bases (e.g., amino groups) Amphoteric molecules are protein molecules that can function as both a weak acid and a weak base

102 Physiological Buffer SystemsThe respiratory system regulation of acid-base balance buffers acid by influencing the carbonic acid-bicarbonate system. There is a reversible equilibrium between: Dissolved carbon dioxide and water Carbonic acid and the hydrogen and bicarbonate ions CO2 + H2O  H2CO3  H+ + HCO3¯

103 Respiratory Mechanisms of Acid-Base BalanceCO2 + H2O  H2CO3  H+ + HCO3¯ Heavy breathing decreases CO2 which moves the reaction to the left Thus, H+ is reduced Shallow breathing increases CO2 which pushes the reaction to the right. Thus, H+ is increased

104 Transport and Exchange of Carbon DioxideIncreased acid pushes the reaction the the left = more Carbonic Acid H+ CO2 + H2O  H2CO3 H+ HCO3– Carbon dioxide Water Carbonic acid Hydrogen ion Bicarbonate ion

105 Transport and Exchange of Carbon DioxideCO2 + H2O  H2CO3 H+ HCO3– Carbon dioxide Water Carbonic acid Hydrogen ion Bicarbonate ion Increased OH- pulls the reaction to the right= water + Bicarbonate OH- H20

106 Which condition would cause a drop in pH?Hyperventilation Hypoventilation Hypovolumemia Hypernatremia Hypokalemia

107 Renal Mechanisms of Acid-Base BalanceChemical buffers can tie up excess acids or bases, but they cannot eliminate them from the body The lungs can eliminate carbonic acid by eliminating carbon dioxide Only the kidneys can rid the body of metabolic acids (phosphoric, uric, and lactic acids and ketones) and prevent metabolic acidosis The ultimate acid-base regulatory organs are the kidneys

108 Renal Mechanisms of Acid-Base BalanceAbsorb in PCT Make more in PCT Excrete Low pH CO2 + H2O  H2CO3  H+ + HCO3¯ High pH Excrete in DCT

109 Hydrogen Ion ExcretionIn response to acidosis: Kidneys generate bicarbonate ions and add them to the blood An equal amount of hydrogen ions are added to the urine

110 Respiratory Acidosis and AlkalosisResult from failure of the respiratory system to balance pH PCO2 is the single most important indicator of respiratory inadequacy PCO2 levels Normal PCO2 fluctuates between 35 and 45 mm Hg Values above 45 mm Hg signal respiratory acidosis Values below 35 mm Hg indicate respiratory alkalosis

111 Respiratory Acidosis and AlkalosisRespiratory acidosis is the most common cause of acid-base imbalance Occurs when a person breathes shallowly, or gas exchange is hampered by diseases such as pneumonia, cystic fibrosis, or emphysema Respiratory alkalosis is a common result of hyperventilation

112 Respiratory Acidosis  H+ CO2 + H2O H2CO3 H+ HCO3– Carbon dioxideOccurs when a person breathes shallowly, or gas exchange is hampered by diseases such as pneumonia, cystic fibrosis, or emphysema. Thus CO2 builds up. H+ CO2 + H2O  H2CO3 H+ HCO3– Carbon dioxide Water Carbonic acid Hydrogen ion Bicarbonate ion CO2 builds up which means H+ builds up

113 Respiratory AlkalosisHyperventilation decreases CO2 levels. H+ CO2 + H2O  H2CO3 H+ HCO3– Carbon dioxide Water Carbonic acid Hydrogen ion Bicarbonate ion CO2 decreases which means H+ decreases

114 Metabolic Acidosis All pH imbalances except those caused by abnormal blood carbon dioxide levels Metabolic acid-base imbalance – bicarbonate ion levels above or below normal (22-26 mEq/L) Metabolic acidosis is the second most common cause of acid-base imbalance Typical causes are ingestion of too much alcohol and excessive loss of bicarbonate ions Other causes include accumulation of lactic acid, shock, ketosis in diabetic crisis, starvation, and kidney failure

115 Metabolic Alkalosis Rising blood pH and bicarbonate levels indicate metabolic alkalosis Typical causes are: Vomiting of the acid contents of the stomach Intake of excess base (e.g., from antacids) Constipation, in which excessive bicarbonate is reabsorbed

116 Acidosis/Alkalosis If the respiratory system is doing what is expected to be doing during acidosis or alkalosis, the cause is likely to be metabolic. If the respiratory system is doing the opposite of what is expected during acidosis, the cause is likely to be respiratory. Work this reasoning out on your own a little.

117 Acidosis/Alkalosis

118 Acidosis/Alkalosis

119 Acidosis/Alkalosis

120 Acidosis/Alkalosis Or, MORE if you want to talk H+ instead of pH.Remember it one way or the other but don’t get them mixed up.

121 Acidosis/Alkalosis Kidneys can compensate for chronic changes by making/excreting HCO3. This brings pH closer to 7.4

122 Acidosis/Alkalosis

123 Acidosis May reflect metabolic production of acid.Is only caused by abnormal respiratory conditions. Results when blood pH exceeds 7.45 Is always corrected by chemical buffer systems. Is compensated for by intestinal secretion of H+.

124 The only organ of the body that can remove excess fixed acids is theSpleen. Liver. Kidney. Lungs. Sweat glands.

125 A patient with alkalosis would experienceHigher blood pressures. Increased sodium retention. Hypoventilation. Increased acid secretion at kidney. Hyperventilation.

126 Acidosis/Alkalosis If a person with acidosis is breathing rapidly, this would be what type of acidosis? Metabolic Acidosis Respiratory Acidosis Metabolic Alkalosis Respiratory Alkalosis

127 Acidosis/Alkalosis If a person with acidosis is breathing slowly this would be what type of acidosis. Metabolic Acidosis Respiratory Acidosis Metabolic Alkalosis Respiratory Alkalosis

128 Acidosis/Alkalosis If a person with alkalosis is breathing slowly, this would be what type of alkalosis? Metabolic Acidosis Respiratory Acidosis Metabolic Alkalosis Respiratory Alkalosis

129 Acidosis/Alkalosis If a person with alkalosis is breathing rapidly, this would be what type of alkalosis? Metabolic Acidosis Respiratory Acidosis Metabolic Alkalosis Respiratory Alkalosis

130 Problems with Fluid, Electrolyte, and Acid-Base BalanceOccur in the young, reflecting: Low residual lung volume High rate of fluid intake and output High metabolic rate yielding more metabolic wastes High rate of insensible water loss Inefficiency of kidneys in infants

131 Case Study: Water IntoxicationJennifer Strange, 28, died after drinking more than six and a half litres of bottled water at KDND January 13, 2007, in a bid to win a Nintendo Wii for her three children.

132 Case Study: Water IntoxicationThis is true, if you drink too much water, normally you will throw up. True False Put A or B (not T or F)

133 Case Study: Water IntoxicationYour body has several methods to cope with dehydration. Choose the following that are correct: Thirst Dilate the efferent arteriole JG and MD cells sense low GFR and promote Na absorption and thus water absorption. ADH All of these are correct

134 Case Study: Water IntoxicationYour body also has several methods to cope with overhydration hydration. Which is correct: Salt appetite The hypothalamus senses decreased osmolarity and stimulates micturition. Throwing up That isn’t true, there are some mechanisms but there isn’t a quick fix for overhydration.

135 Case Study: Water IntoxicationWhat would you expect your body to do when it is overhydrated. What are the slow fixes?

136 Case Study: Water IntoxicationEva was reported to be a nurse. Why would you expect water intoxication to be dangerous. What symptoms would you expect?

137 Case Study: Water Intoxication: Head hurts and light headedIndicate which of the following is correct: Increased fluid equals increased blood pressure and edema. She has excess fluid in her brain. Na and other ions are diluted, resulted in altered neuronal function. Cells will swell, taking up more space causing pain. Normal chemical reactions will be slowed because the cells are bigger and reactants are further apart. All of these sound good to me.

138 Case Study: Water Intoxication: Head hurts and light headedHow would using Gatorade, instead of water, changed the situation?