Chapter 15
Fluid and Acid-Base Balance
TEST QUESTIONS
Multiple Choice
1. Variation in percent body water among individuals is primarily due to differences in: (a) amount of adipose tissue.
(b) total muscle mass. (c) vasopressin secretion. (d) drinking habits.
(e) glomerular filtration rate.
ANSWER: a
2. The largest percentage of water is located in what “compartment?”
(a) synovial fluids. (b) plasma.
(c) interstitial fluids. (d) intracellular fluids. (e) extracellular fluids.
ANSWER: d
3. The tissue in the body containing the lowest percentage of water is the:
(a) skin. (b) skeleton. (c) muscle. (d) internal organs. (e) adipose (fat).
ANSWER: e
4. The component that constitutes the largest percentage of body weight is:
(a) protein. (b) H2O.
(c) Na+.
(d) carbohydrate. (e) phospholipid.
ANSWER: b
5. The ICF contains about ________ of the total water of the body.
(a) 1/10 (b) 1/4 (c) 1/2 (d) 2/3 (e) 5/6
ANSWER: d
6. A __________ exists when total body input of a particular substance equals its total body output. (a) positive balance.
(b) negative balance. (c) stable balance. (d) state of equilibrium. (e) steady state.
ANSWER: c
7. Extracellular fluid: (a) includes plasma.
(b) includes interstitial fluid.
(c) constitutes a smaller percentage of total body water than does intracellular fluid.
(d) includes both plasma and interstitial fluid. (e) all of these answers.
ANSWER: e
8. Extracellular fluid:
(a) constitutes a greater percentage of total body water than does intracellular fluid.
(b) osmolarity must be regulated to prevent an acid-base imbalance because the hydrogen ions might become too concentrated or too dilute in the body fluids.
(c) volume must be regulated to prevent the cells from swelling or shrinking.
(d) more than one of the above. (e) none of these answers.
ANSWER: e
9. Select the transcellular fluid that serves as a shock absorber in the joints.
(a) intraocular. (b) pericardial. (c) peritoneal. (d) pleural. (e) synovial.
ANSWER: e
10. Interstitial fluid:
(b) is the true internal environment of the body. (c) represents a larger percentage of total body weight than does intracellular fluid.
(d) is both the largest component of the extracellular fluid and the true internal environment of the body.
(e) all of these answers.
ANSWER: d
11. Transcellular fluid:
(a) is the sum of fluid within all of the cells. (b) consists of a number of small specialized fluid volumes, all of which are secreted by specific cells into a particular body cavity to perform a
specialized function.
(c) plays a crucial role in fluid balance. (d) includes the lymph.
(e) lies in the spaces between the cells.
ANSWER: b
12. The major source of water loss from the body is: (a) feces.
(b) insensible respiratory loss. (c) insensible skin loss. (d) sweat.
(e) urine.
ANSWER: e
13. When large amounts of pure water are consumed: (a) the volume of the ICF will decrease.
(b) the volume of the ECF will decrease. (c) the ECF becomes hypertonic to the ICF. (d) osmolarities of the ICF and ECF will drop. (e) none of these answers.
ANSWER: d
14. When water is lost from the ECF but electrolytes are retained:
(a) both ECF and ICF become more dilute. (b) osmosis moves water from the ICF to the ECF. (c) the osmolarity of the ECF drops.
(d) there is an increase in the volume of the ICF (e) water levels remain the same.
ANSWER: b
15. The barrier between the plasma and interstitial fluid:
(a) is the blood vessel walls. (b) is the plasma membrane.
(c) transports materials between these two fluid compartments by both passive and active means.
(d) two of these answers. (e) all of these answers.
ANSWER: a
16. The primary electrolyte in the extracellular fluid is:
(a) calcium ion. (b) chloride. (c) phosphate. (d) potassium ion. (e) sodium ion.
ANSWER: e
17. The primary anion of the ECF is: (a) bicarbonate.
(b) chloride. (c) phosphate. (d) sodium ion. (e) potassium ion.
ANSWER: b
18. The primary ECF cation is __________, and the primary ICF cation is __________.
(a) K+, Na+
(b) K+, Ca2+
(c) Ca2+, Na+
(d) Na+, K+
(e) Na+, Ca2+
ANSWER: d
19. The ion in greatest concentration within the cytoplasm is:
(a) calcium ion. (b) chloride. (c) phosphate. (d) potassium ion. (e) sodium ion.
ANSWER: d
20. The unequal distribution of sodium and potassium between the ICF and ECF:
(a) results from sodium being pumped in and potassium being pumped out of cells.
(b) results from sodium being pumped out and potassium being pumped into cells.
(c) results from ATPase activity. (d) both (a) and (b) above. (e) both (b) and (c) above.
21. The primary reason that extracellular fluid volume must be closely regulated is:
(a) to prevent changes in ICF osmolarity. (b) to maintain adequate urine formation. (c) to maintain proper blood pressure.
(d) to prevent cells from swelling or shrinking. (e) to allow changes in ICF volume.
ANSWER: c
22. Why would eating a very salty snack make you thirsty?
(a) It would cause decreased ECF volume. (b) It would decrease the osmolarity of the ECF. (c) It would inhibit the hypothalamic
osmoreceptors.
(d) It would stimulate the hypothalamic osmoreceptors.
(e) It would immediately cause more urine output.
ANSWER: d
23. Which of the following are compensatory measures for a fall in arterial blood pressure? (a) Increased cardiac output and increased total peripheral resistance as a result of the baroreceptor reflex.
(b) A shift of fluid out of the interstitial compartment into the vasculature.
(c) A reduction in the urinary excretion of salt and accompanying fluid.
(d) Both (a) and (b) above. (e) All of these answers.
ANSWER: e
24. The most important factor in the long-term regulation of ECF volume is:
(a) maintenance of salt balance. (b) maintenance of water balance. (c) thirst.
(d) the baroreceptor reflex.
(e) fluid shifts between the interstitial fluid and plasma.
ANSWER: a
25. The vast majority of the extracellular fluid’s osmotic activity is contributed by:
(a) plasma proteins.
(b) Na+ and its attendant anions.
(c) K+ and its attendant anions.
(d) Ca2+ and its attendant anions.
(e) red blood cells.
ANSWER: b
26. The baroreceptor reflexes affect sodium balance by:
(a) causing release of renin.
(b) causing the release of vasopressin.
(c) lowering GFR through vasoconstriction of afferent arterioles.
(d) lowering GFR through vasodilation of afferent arterioles.
(e) none of these answers.
ANSWER: c
27. Sodium is directly or indirectly controlled through all these mechanisms except:
(a) the baroreceptor reflexes.
(b) the renin-angiotensin mechanism. (c) aldosterone activity.
(d) changes in GFR.
(e) by altering gastrointestinal absorption.
ANSWER: e
28. A drop in arterial blood pressure would trigger: (a) decreased GFR.
(b) release of aldosterone.
(c) increased sodium reabsorption. (d) decreased chloride excretion. (e) all of these answers.
ANSWER: e
29. The amount of Na+ filtered is equal to the:
(a) CMO x GRF.
(b) plasma concentration x CMO. (c) plasma concentration x GRF. (d) urine output x CMO. (e) urine output x GRF.
ANSWER: c
30. Osmotic activity across the:
(a) capillary wall is not due to the unequal distribution of plasma proteins in the plasma and interstitial fluid.
(b) cellular plasma membranes is not related to any differences in ionic concentration between the ECF and ICF.
(c) cellular plasma membranes is not related to differences in protein composition between the ECF and ICF.
(d) both (a) and (b) above. (e) both (a) and (c) above.
ANSWER: c
(a) increased facultative reabsorption of water occurs.
(b) urinary output increases.
(c) vasopressin secretion is decreased. (d) the ECF osmolarity becomes hypotonic. (e) all of these answers.
ANSWER: a
32. Which of the following is not a potential cause of hypertonicity in the body?
(a) water deprivation. (b) heavy sweating.
(c) excess vasopressin secretion. (d) diabetes insipidus.
(e) severe diarrhea.
ANSWER: c
33. Diabetes insipidus:
(a) is due to excess vasopressin secretion. (b) is due to vasopressin deficiency. (c) gives rise to hypertonicity of the ECF (d) both (a) and (c) above.
(e) both (b) and (c) above.
ANSWER: e
34. When the ECF becomes hypertonic water: (a) movement is unaffected.
(b) moves into the cells by active transport. (c) moves into the cells by osmosis.
(d) moves out of the cells by active transport. (e) moves out of the cells by osmosis.
ANSWER: e
35. The importance of regulating ECF osmolarity is: (a) to help maintain blood pressure.
(b) to prevent the urine from becoming too concentrated.
(c) to prevent fluid shifts between the cells and the extracellular fluid, which could produce profound symptoms as the cells swell or shrink.
(d) to prevent spontaneous depolarization of nerve and muscle cell membranes because of shifts in Na+ balance.
(e) to prevent an acid-base imbalance if the hydrogen ions were to become too concentrated or too dilute in the body fluids.
ANSWER: c
36. The main control for salt balance is: (a) control of salt intake.
(b) control of salt output in the sweat.
(c) control of salt output in the feces. (d) control of salt output in the urine. (e) regulation through salt hunger.
ANSWER: d
37. Which of the following statements concerning hypotonicity is correct?
(a) During hypotonicity, water enters the cells by osmosis.
(b) The only cause of hypotonicity is drinking excess fluid.
(c) Hypotonicity is a major consequence of diabetes mellitus, which is a deficiency of vasopressin.
(d) Hypotonicity is usually associated with a negative water balance.
(e) Common symptoms of hypotonicity include dry skin and sunken eyeballs.
ANSWER: a
38. If an individual is overhydrated:
(a) H2O will move by osmosis into the cells.
(b) both the ECF and ICF compartments will be hypotonic after the fluid shift has occurred. (c) symptoms might include confusion, headache, lethargy, weakness, and edema.
(d) two of these answers. (e) all of these answers.
ANSWER: e
39. If the ECF’s osmolarity increases:
(a) water will shift from the ICF into the ECF. (b) water will not shift between the ECF and the ICF.
(c) water will move from the ECF into the ICF. (d) vasopressin secretion will decrease. (e) potassium and sodium will compensate.
ANSWER: a
40. All of the following will occur during water intoxication except:
(a) ICF hypotonicity.
(b) ECF hypotonicity circulatory. (c) excess free water retention. (d) water movement from ICF to ECF. (e) overhydration.
ANSWER: d
41. When isotonic fluid is added to the ECF, fluid will:
(b) not shift between the ECF and ICF. (c) shift from the ECF into the ICF. (d) none of these answers.
ANSWER: b
42. Salt balance in humans:
(a) depends primarily upon control of Na+ intake
through salt hunger.
(b) depends primarily upon control of Na+ output
by the kidneys. (c) is poorly regulated.
(d) depends upon Na+ secretion by the kidneys.
(e) is not affected by aldosterone secretion.
ANSWER: b
43. Which of the following statements concerning hypotonicity of the body fluids is incorrect? (a) Hypotonicity can occur as a result of diabetes insipidus.
(b) Hypotonicity occurs when excess free H2O is
present.
(c) Drowsiness, headache, confusion, lethargy, weakness, and edema are symptoms associated with hypotonicity.
(d) Drinking excess fluid is a cause of hypotonicity.
(e) The cells become swollen.
ANSWER: a
44. Hypothalamic osmoreceptors are nearest to: (a) angiotensin-secreting cells.
(b) carotid baroreceptors. (c) the adrenal cortex. (d) the adrenal medulla. (e) vasopressin-secreting cells.
ANSWER: e
45. When there is excess Na+ in the body:
(a) the plasma volume is expanded, and arterial blood pressure is increased.
(b) as a compensatory measure, the GFR is increased.
(c) as a compensatory measure, aldosterone secretion is increased to increase the amount of Na+ reabsorbed.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
46. The amount of Na+ excreted in the urine equals the
amount of Na+ ______ minus the amount of Na+
______.
(a) filtered, reabsorbed (b) ingested, filtered
(c) ingested, metabolically consumed (d) ingested, placed in storage (e) secreted, reabsorbed
ANSWER: a
47. Which is a source of water input? (a) fluid intake.
(b) ingested food.
(c) chemical reactions within the cells that convert food and O2 into energy.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: e
48. Metabolic water:
(a) results from cellular respiration. (b) is roughly 15% of daily water input. (c) its production increases during times of dehydration to compensate for water loss. (d) both (a) and (b) above.
(e) both (a) and (c) above.
ANSWER: d
49. Insensible water loss includes loss: (a) during cellular metabolism. (b) from the lungs.
(c) from sweat. (d) in the feces. (e) none one of these.
ANSWER: b
50. What is the primary regulatory mechanism to maintain water balance in the body?
(a) control of intake through thirst. (b) control of sweating.
(c) control of output through regulation of urine production by the kidney.
(d) oral metering.
(e) control of insensible water loss.
ANSWER: c
51. The thirst mechanism is invoked when: (a) the plasma osmolarity increases. (b) the plasma osmolarity decreases.
(e) both (a) and (c) above.
ANSWER: e
52. Vasopressin:
(a) is released when hypothalamic osmoreceptors are activated.
(b) atrial volume are activated.
(c) causes increased systemic vasoconstriction. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: e
53. Select the incorrect statement about acids. (a) Carbohydrates are acidic.
(b) HCl is one example. (c) They can be strong or weak. (d) They dissociate to produce anions.
(e) They dissociate to produce free hydrogen ions.
ANSWER: a
54. Which of the following statements concerning acids is incorrect?
(a) Acids can dissociate in solution to yield free hydrogen ions and anions.
(b) All substances that contain hydrogen are considered to be acids.
(c) A strong acid has a greater tendency to dissociate than does a weak acid.
(d) The extent of dissociation for a given acid is a constant, K.
(e) Only free hydrogen ions contribute to the acidity of a solution.
ANSWER: b
55. Which acid below would be considered a strong acid?
(a) One with a dissociation constant (K) = 0.05 (b) One with a dissociation constant (K) = 0.10 (c) One with a dissociation constant (K) = 0.47 (d) One with a dissociation constant (K) = 0.53 (e) One with a dissociation constant (K) = 0.99
ANSWER: e
56. pH:
(a) equals the logarithm to the base 10 of the reciprocal of the hydrogen-ion concentration. (b) can be calculated if the HCO3- and CO2
concentration in the body fluids is known, even if the H+ concentration is unknown.
(c) is higher in arterial blood than venous blood. (d) both (a) and (b) above.
(e) all of these answers.
ANSWER: e
57. pH is:
(a) equal to log 1/[H+].
(b) equal to pK + log [HCO3-]/[CO2].
(c) low when acidosis is present.
(d) both equal to log 1/[H+] and pK + log [HCO 3-]/
[CO2].
(e) all of these answers.
ANSWER: e
58. Given the following information, what is the pH? ratio of [HCO3]/[CO2] = 20/0.5
pK = 6.1 log of 10 = 1.0 log of 20 = 1.3 log of 40 = 1.6
(a) pH = 7.0 (b) pH = 7.4 (c) pH = 7.1 (d) pH = 7.7
(e) It is impossible to determine the pH with the information provided.
ANSWER: d
59. A pH of 4 is _________ times as acidic as a pH of 7.
(a) 10 (b) 100 (c) 1,000 (d) 10,000 (e) 100,000
ANSWER: c
60. The pH of a solution with a H+ concentration of
0.0000567 is: (a) between 4 and 5. (b) between 5 and 6. (c) between 6 and 7. (d) between 7 and 8. (e) none of these answers.
ANSWER: a
61. Which of the following is not influenced by a change in the pH of body fluids?
(e) nerve and muscle excitability.
ANSWER: a
62. Which of the following symptoms is associated with acidosis?
(a) extreme nervousness. (b) disoriented and comatose.
(c) tingling, “pins and needles” sensations. (d) muscle twitches and muscle spasms. (e) convulsions.
ANSWER: b
63. An increased secretion of H ions in the kidney has the greatest direct effect on the tubular secretion of ________ ions.
(a) calcium (b) chloride (c) phosphate (d) potassium (e) sodium
ANSWER: d
64. Which of the following symptoms is not associated with alkalosis?
(a) disoriented and comatose.
(b) tingling “pins and needles” sensations. (c) muscle twitches and muscle spasms. (d) extreme nervousness.
(e) convulsions.
ANSWER: a
65. Normal blood pH: (a) is slightly basic. (b) is slightly alkaline.
(c) falls between 7.35 and 7.45. (d) varies greatly.
(e) both (a) and (c) above.
ANSWER: e
66. Which of the following is normally the major source of hydrogen ions in the body?
(a) phosphoric and sulfuric acids formed during the metabolism of dietary proteins.
(b) lactic acid production by the muscles during exercise.
(c) carbonic acid generated from metabolically produced CO2.
(d) natural acids found in foods, such as citric acid.
(e) fatty acids produced during fat metabolism.
ANSWER: c
67. Select the primary buffer system in the ECF. (a) bicarbonate/carbonic acid.
(b) chloride/hydrochloric acid. (c) hemoglobin.
(d) phosphate. (e) protein.
ANSWER: a
68. Which chemical buffer system primary buffers against carbonic acid changes?
(a) bicarbonate. (b)protein. (c) hemoglobin. (d) phosphate (e) ammonium.
ANSWER: c
69. H+ generated from CO
2 at the tissue level is:
(a) the major source of hydrogen ion in the body. (b) normally buffered in transit between the tissues and the lungs by hemoglobin. (c) responsible for the fact that the pH of the venous blood is higher than the pH of the arterial blood.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: d
70. Which of the following statements concerning chemical buffer systems is incorrect?
(a) A chemical buffer system consists of a pair of substances involved in a reversible reaction, one that can yield free H+ and one that can bind with
free H+.
(b) A chemical buffer system minimizes changes in the pH of a solution when an acid or base is added to or removed from the solution.
(c) Buffers respond to pH changes in 3 minutes. (d) A buffer system cannot actually eliminate hydrogen ions from the body.
(e) Buffer systems act according to the law of mass action.
ANSWER: c
71. Chemical buffer systems:
(a) respond in 1 to 3 minutes to changes in hydrogen ion concentration.
(c) promote H+ excretion by the kidneys when
acidosis is present.
(d) are the most powerful mechanism available for regulating changes in [H+] within the body.
(e) buffers changes in acid or base levels.
ANSWER: e
72. Chemical buffer systems:
(a) can act within a fraction of a second to buffer changes in [H+].
(b) are the only mechanism available for regulating changes in [H+] within the body.
(c) actually eliminate acid from the body. (d) both (a) and (c) above.
(e) all of these answers.
ANSWER: a
73. H+ generated at the tissue level from CO 2 is
buffered in transit between the tissues and the lungs primarily by:
(a) hemoglobin.
(b) phosphate buffer system. (c) H2CO3: HCO3- buffer system.
(d) plasma proteins. (e) respiratory regulation.
ANSWER: a
74. Which of the following statements concerning the respiratory mechanism of pH control is incorrect? (a) Respiratory rate and depth increase as a compensatory measure to combat metabolic acidosis.
(b) Tthe respiratory system can compensate completely for metabolic acidosis.
(c) The respiratory responses to acid-base imbalances represent the second line of defense against changes in pH of the body fluids. (d) Metabolic alkalosis inhibits (depresses) respiration.
(e) The respiratory system responds to changes in [H+] within 1 to 3 minutes.
ANSWER: b
75. Which of the following statements concerning the respiratory mechanism of pH control is correct? (a) Respiratory rate and depth decrease as a compensatory measure to combat metabolic acidosis.
(b) The respiratory system can compensate completely for uremic acidosis.
(c) Metabolic alkalosis inhibits (depresses) the respiratory center.
(d) The respiratory responses to acid-base imbalances represent the first line of defense against changes in pH of the body fluids.
(e) The respiratory system responds to changes in [H+] only if the kidneys are unable to cope with
the change.
ANSWER: c
76. When the concentration of H+ increases above
normal, for compensation the response is a(n): (a) decreased excretion of H+ in the urine.
(b) increased concentration of H+ in the plasma.
(c) increased reabsorption of all filtered bicarbonate ions.
(d) increased secretion of aldosterone from the posterior pituitary.
(e) synthesis of H+ by acid dissociation.
ANSWER: c
77. If the tubular filtrate becomes too acidic, which of the following is secreted by the tubular epithelial cells to buffer the secreted H+?
(a) HCO3
-(b) OH
-(c) NH3
(d) NH4+
(e) basic phosphate
ANSWER: c
78. The kidney tubular cells secrete NH3:
(a) when the urinary pH becomes too high. (b) when the body is in a state of alkalosis. (c) to buffer the acid phosphate excreted in the urine.
(d) when there is excess NH3 in the body fluid.
(e) to enable further renal secretion of H+.
ANSWER: e
79. The [HCO3-]/[CO2] is 20/2, what is occurring?
(a) Uncompensated respiratory acidosis. (b) Uncompensated respiratory alkalosis. (c) Uncompensated metabolic acidosis. (d) Uncompensated metabolic alkalosis. (e) The body fluids are at normal pH.
ANSWER: a
80. A patient with lung congestion would: (a) have higher levels of carbonic acid in the blood.
(c) be making use of chemical buffers to a greater extent.
(d) both (a) and (b) above. (e) all of these answers.
ANSWER: e
81. Which of the following statements concerning HCO3- excretion by the kidneys is incorrect?
(a) During HCO3- reabsorption, HCO3- in the
tubular fluid is actively cotransported by K+.
(b) HCO3- is not excreted at pH =7.4.
(c) Secretion of H+ is accompanied by the addition
of new HCO3- to the plasma.
(d) HCO3- excretion increases during alkalosis.
(e) None of these answers.
ANSWER: a
82. Which of the following conditions would be a cause of metabolic acidosis?
(a) severe diarrhea. (b) severe vomiting. (c) aspirin poisoning. (d) emphysema.
(e) none of these answers.
ANSWER: a
83. Vomiting of gastric contents: (a) can lead to dehydration. (b) can cause metabolic acidosis. (c) can cause metabolic alkalosis.
(d) both can lead to dehydration and cause metabolic acidosis.
(e) both can lead to dehydration and cause metabolic alkalosis.
ANSWER: e
84. Which of the following statements concerning the kidneys’ response to increased [H+] in the body
fluids is incorrect?
(a) When [H+] increases, the kidneys conserve
HCO3- by reabsorbing more HCO3- and reducing
its excretion in the urine.
(b) When [H+] increases, the kidneys secrete more
H+ to be eliminated in the urine.
(c) When [H+] increases, the kidneys secrete more
basic phosphate to buffer the H+ in the tubular
filtrate.
(d) When [H+] decreases, the kidneys excrete
more HCO3- into the urine.
(e) When severe acidosis is present, the kidney tubules secrete NH3.
ANSWER: c
85. If the [HCO3]/[CO2] ratio is 40/1:
(a) the kidneys will decrease H+ excretion and
increase HCO3- excretion to compensate.
(b) respiration will become shallow and slow to compensate.
(c) respiration will become deep and rapid to compensate.
(d) both (a) and (b) above. (e) both (a) and (c) above.
ANSWER: d
86. During respiratory compensation for metabolic alkalosis:
(a) breathing becomes shallower. (b) breathing becomes slower. (c) CO2 levels in the body decrease.
(d) both (a) and (b) above. (e) both (b) and (c) above.
ANSWER: d
87. The respiratory system can not fully compensate for metabolic acidosis because:
(a) the peripheral and central chemoreceptors respond to pH changes in a different manner. (b) changes in acid levels occur due to changes in carbon dioxide levels.
(c) metabolic acid production is too great. (d) both (a) and (b) above.
(e) all these answers.
ANSWER: d
True/False
88. Water is the most abundant component of the body, making up over 95 percent of the body weight.
ANSWER: False
89. The percentage of body water varies from person to person.
ANSWER: True
90. The tissue with the lowest percentage of water is the skeleton.
91. Water is freely permeable through all cell membranes.
ANSWER: True
92. The body normally loses 10 grams of salt daily.
ANSWER: False
93. Intracellular fluid is divided into two
compartments, the plasma fluid and the interstitial fluid.
ANSWER: False
94. Extracellular fluid volume depends primarily on the sodium load in the body.
ANSWER: True
95. The main reason that extracellular fluid volume must be closely regulated is to prevent fluid shifts from occurring between the ICF and ECF.
ANSWER: False
96. The main reason ECF volume must be regulated is to maintain proper cell volume.
ANSWER: False
97. The secretion of aldosterone promotes the reabsorption of sodium.
ANSWER: True
98. The ECF volume and osmolarity are regulated primarily by the kidneys.
ANSWER: True
99. Cells in a hypertonic ECF tend to lose water by osmosis.
ANSWER: True
100.Osmolarity is a measure of the concentration of the individual solute particles dissolved in a fluid.
ANSWER: True
101.Each intracellular protein exerts more osmotic effect than each intracellular phosphate ion because the proteins are larger.
ANSWER: False
102.Diabetes insipidus develops in the body from a deficiency of insulin.
ANSWER: False
103.Diabetes insipidus often leads to hypertonicity of the body fluids.
ANSWER: True
104.A hypertonic solution has a higher concentration of solutes and a lower concentration of H2O than
an isotonic solution.
ANSWER: True
105.A hypotonic solution has a lower concentration of solutes and higher concentration of water than a hypertonic solution.
ANSWER: True
106.When the body becomes dehydrated (H2O deficit),
both urinary output and thirst increase as compensatory measures.
ANSWER: False
107.Vasopressin is normally secreted when a deficit of water develops in the body.
ANSWER: True
108.The only cause of hypotonicity is drinking excess fluid.
ANSWER: False
109.Hypertonicity in the ECF is sensed by osmoreceptors in the hypothalamus.
ANSWER: True
110.Common symptoms of hypotonicity include dry skin, parched tongue, and sunken eyeballs.
ANSWER: False
111.Control of salt balance in humans is accomplished primarily by control of salt intake via a well-developed salt hunger.
112.Salt concentration in the body varies markedly between individuals depending on how much salt they consume.
ANSWER: False
113.Renal regulation of salt is the primary means of achieving salt balance.
ANSWER: True
114.Loss of water from the lungs is one example of sensible loss.
ANSWER: False
115.In a normal, healthy person, H2O intake equals
H2O output.
ANSWER: True
116.Insensible water loss includes water lost from the lungs during expiration and water lost from the skin during sweating.
ANSWER: False
117.Insensible H2O loss includes water lost as a result
of metabolic reactions within the cells.
ANSWER: False
118.The primary factor responsible for regulating H2O
balance in the body is control of fluid intake via the thirst mechanism.
ANSWER: False
119.The thirst center is closely related to or perhaps identical with the cells that secrete vasopressin.
ANSWER: True
120.Fluid consumption is influenced by other factors in addition to the thirst mechanism involving osmoreceptors.
ANSWER: True
121.The hypothalamus controls both thirst and vasopressin secretion.
ANSWER: True
122.If the pH of body fluids is 7.3, then alkalosis is present because neutral pH equals 7.0.
ANSWER: False
123.If the pH of body fluids is 7.3, acidosis is said to exist even though a solution with a pH of 7.30 is chemically considered to be basic.
ANSWER: True
124.A pH of 3 is 100 times as acidic as a pH of 5.
ANSWER: True
125.The pH of arterial blood is lower than the pH of venous blood.
ANSWER: True
126. A pH of less than 6.8 or greater than 8.0 is not compatible with life.
ANSWER: True
127.Alkalosis eventually leads to unconsciousness and coma.
ANSWER: False
128.Regulation of hydrogen ion concentration is important in the maintenance of proper enzyme function.
ANSWER: True
129.As H+ increases, K+ secretion also increases
because of the intimate relationship between H+
secretion and K+ secretion by the kidneys.
ANSWER: False
130.Bicarbonate ions can combine with free H+,
removing a source of acidity and opposing acidosis.
ANSWER: True
131 Normally the major source of H+ in the body is
from the formation of sulfuric and phosphoric acid produced during metabolism of dietary proteins that contain sulfate and phosphate groups.
132.The major source of H+ in the body fluids is the
carbonic acid generated from metabolic production of CO2.
ANSWER: True
133.A chemical buffer system consists of a pair of substances involved in a reversible reaction, one that can yield free H+ and one that can bind with
free H+.
ANSWER: True
134.Buffer systems contain strong acids such as HCl.
ANSWER: False
135.A chemical buffer system enables a solution to resist a marked change in pH upon addition or loss of acid or base.
ANSWER: True
136.Chemical buffer systems are the most powerful mechanism available for defending against changes in [H+] because they respond the fastest.
ANSWER: False
137.The phosphate buffer system serves as an important urinary buffer.
ANSWER: True
138.During respiratory compensation for metabolic alkalosis, breathing becomes slower and shallower.
ANSWER: True
139.The kidneys are the first line of defense against changes in acid-base balance because they are the most powerful mechanism for maintaining pH.
ANSWER: False
140.Basic phosphate is secreted by the kidney tubular cells to buffer hydrogen ion when the tubular fluid becomes too acidic.
ANSWER: False
141.When [H+] decreases, the kidneys excrete less
HCO3- into the urine.
ANSWER: False
142.The kidneys secrete additional H+ and conserve
HCO3- to compensate for increased H+
concentration in the body fluids.
ANSWER: True
143. Slow, shallow breathing allows carbonic acid to build up in the blood, returning pH back to normal.
ANSWER: True
144.Respiratory alkalosis occurs as a consequence of hyperventilation, because CO2 is blown off more
quickly than it is produced, decreasing the amount of carbonic acid in the body fluids.
ANSWER: True
145.The respiratory system can compensate completely for metabolic acidosis.
ANSWER: False
146.Carbon dioxide is unintentionally increased as a cause of respiratory acidosis but is deliberately increased as a compensation for metabolic alkalosis.
ANSWER: True
147. H+ secretion is coupled to bicarbonate
reabsorption.
ANSWER: True
148.Bicarbonate ions that enter the plasma during HCO3- reabsorption are not the same HCO3- ions
that were filtered.
ANSWER: True
149. During acidosis, ammonia plays a key role in allowing for continued renal H+ secretion.
ANSWER: True
Fill in the Blank
150.On the average, ________________% of the body weight consists of H2O.
151.The ________ fluid provides lubrication for the movements of the heart.
ANSWER: pericardial
152.The quantity of any particular substance in the ECF is considered to be a readily available internal ________.
ANSWER: pool
153.When total body input of a particular substance equals its total body output, a ______________ balance exists.
ANSWER: stable
154.The blood plasma and __________ make up the ECF.
ANSWER: interstitial fluid
155.The true internal environment is the ________________.
ANSWER: interstitial fluid
156.The total load of _______ determines the total amount of water that will be retained in the ECF by osmosis.
ANSWER: sodium
157.The force responsible for movement of H2O
between the ECF and ICF is ______________.
ANSWER: osmotic pressure differences
158.Baroreceptors are sensitive to changes in the blood ________.
ANSWER: pressure
159.The principal ECF cation is _______________, which is accompanied primarily by the anion ________________ and to a lesser extent ___________________.
ANSWER: sodium, chloride, bicarbonate
160._________ are too large to pass through the pores in the capillary and enter the interstitial fluid.
ANSWER: plasma proteins
161.The barrier between the plasma and interstitial fluid is the __________________.
ANSWER: blood vessel walls
162.Cells change in size by _________ when immersed in a hypertonic ECF.
ANSWER: shrinking
163.An imbalance in the physical forces,
________________ and __________________, is primarily responsible for producing movement of fluid between the plasma and interstitial fluid.
ANSWER: capillary blood pressure, plasma colloid osmotic pressure
164.The barrier between the ECF and ICF is the ___________ ___________________.
ANSWER: plasma membrane of cells
165.When an isotonic fluid is injected into the ECF compartment, it changes volume by ________ in size.
ANSWER: increasing
166.Urine excretion is the most important _________ mechanism for controlling water balance.
ANSWER: output
167. The major intracellular cation is ___________.
ANSWER: potassium
168. ________ are responsible for the slightly negative charge associated with the plasma membrane.
ANSWER: proteins
169.Osmoreceptor input normally is the dominant factor for controlling the secretion of
___________ from the pituitary.
ANSWER: vasopressin
170.The amount of Na+ excreted depends on
_______________ minus ________________.
ANSWER: the amount of Na+ filtered, the amount of
171.A strong acid dissociates to form _________ ions in solution, which influence the pH.
ANSWER: hydrogen
172.A(n) ________ is a substance that combines with H+ and removes them from solution.
ANSWER: base
173.The amount of Na+ filtered is controlled by
regulating the _________________.
ANSWER: GFR
174.The amount of Na+ reabsorbed is regulated
primarily by the _________________ system.
ANSWER: renin-angiotensin-aldosterone
175.The pH of venous blood is usually about ________.
ANSWER: 7.35
176.Alkalosis occurs when the pH of the blood is above ________.
ANSWER: 7.45
177.The amount of free H2O reabsorbed is regulated
primarily by the hormone ____________________.
ANSWER: vasopressin.
178._________ is a change in pH that causes overexcitability of the nervous system.
ANSWER: alkalosis
179._________________ are a special group of hydrogen-containing substances that dissociate in solution to liberate free H+ and anions.
ANSWER: Acids
180.A chemical _________ is a mixture of two compounds that resist changes in the pH.
ANSWER: buffer
181.A(n) _________________ is a substance that can combine with a free H+, thus removing it from
solution.
ANSWER: base
182.The _________ are the group of molecules that are the most plentiful buffers in the body.
ANSWER: proteins
183.Acidosis changes the rate and depth of breathing by ________ it.
ANSWER: increasing
184.A pH of ___________ is considered to be chemically neutral. The normal pH of plasma is ______________. The pH range compatible with life is _________ to _________.
ANSWER: 7.0, 7.4, 6.8, 8.0
185.A chemical buffer system is a(n) _____ of chemical compounds involved in a reversible reaction, one that can yield free _____and one that can bind free _____, which together minimize changes in _____ when either an acid or a base in added to or removed from the solution.
ANSWER: pair, H+, H+, pH
186.The filtration rate of H+ equals plasma [H+] times
the ________.
ANSWER: GFR
187.The secretion of H+ by the tubular cells of the
kidney is influenced by the gas ________.
ANSWER: carbon dioxide
188.Acidosis leads to the _________ secretion of H+ in
the urine.
ANSWER: increased
189.The two important urinary buffers are filtered phosphate buffers and secreted ________.
ANSWER: ammonia
190._________ acidosis results from the abnormal retention of carbon dioxide.
191.An absence of the hormone _________ leads to the formation of keto acids in the body.
ANSWER: insulin
192.________ is the acid found in the stomach.
ANSWER: HCl
Matching
193.Indicate which fluid imbalance is being described by writing the appropriate letter in the blank using the following answer code:
(a) overhydration (b) dehydration
(c) both overhydration and dehydration (d) neither overhydration or dehydration
_____ Symptoms include dry skin, parched tongue, and sunken eyeballs.
_____ Water enters the cells by osmosis.
_____ The body fluids have a lower concentration of solutes than normal.
_____ ECF and ICF become hypertonic. _____ Cells become swollen.
_____ No fluid shift occurs between the ECF and ICF.
_____ Occurs with water deprivation. _____ Cells shrink.
_____ ECF and ICF become hypotonic. _____ Convulsions and coma may occur. _____ This occurs as a consequence of diabetes
insipidus.
_____ Occurs with heavy vomiting.
_____ Osmolarity of the body fluids is decreased. _____ This occurs as a consequence of excessive
fluid intake.
_____ This occurs as a consequence of excessive vasopressin secretion.
_____ Vasopressin secretion is stimulated as a compensatory mechanism.
_____ Increased urinary output occurs as a compensatory mechanism.
ANSWER: b, a, a, b, a, d, b, b, a, c, b, b, a, a, a, b, a
194.When a person has diarrhea, she or she loses excessive salt and water from the body. This fluid loss results in Na+ depletion, dehydration, a
decreased extracellular fluid volume, a reduction in plasma volume, and a decreased systemic arterial blood pressure.
The following refer to the sequence of events that occur to compensate for this fluid loss. Indicate whether each factor listed
(a) exhibits no change (b) is increased, or (c) is decreased,
_____ sympathetic activity to the afferent arterioles of the nephrons
_____ caliber of the afferent arterioles _____ glomerular capillary blood pressure _____ net filtration pressure
_____ GFR
_____ amount of Na+ and H
2O filtered
_____ renin secretion
_____ angiotensin I and II production _____ aldosterone secretion
_____ amount of Na+ reabsorbed
_____ amount of Na+ excreted
_____ vasopressin secretion
_____ permeability of distal and collecting tubules to H2O
_____ amount of H2O reabsorbed.
_____ amount of H2O excreted.
_____ urinary volume. _____ thirst.
ANSWER: b, c, c, c, c, c, b, b, b, b, c, b, b, b, c, c, b
195. Indicate whether the item in question is referring to regulation of ECF volume or regulation of ECF osmolarity by using the following answer code: (a) refers to regulation of ECF volume
(b) refers to regulation of ECF osmolarity
_____ Is primarily important to prevent fluid shifts between the ECF and ICF.
_____ Is primarily important in the long-term regulation of arterial blood pressure. _____ Depends primarily on Na+ balance.
_____ Depends primarily on H2O balance.
196.Match buffer system with correct characteristic.
(a) hemoglobin buffer system (b) phosphate buffer system (c) protein buffer system (d) H2CO3:HCO3- buffer system
_____ buffers H+ generated from carbonic acid
_____ primary ECF buffer for noncarbonic acids _____ primary intracellular buffer
_____ important urinary buffer
ANSWER: a, d, c, b
197. Indicate which acid-base abnormality is represented by the [HCO3-]/[CO2] ratio listed by
writing the appropriate letter in the blank. (a) uncompensated respiratory acidosis (b) uncompensated metabolic acidosis (c) uncompensated respiratory alkalosis (d) uncompensated metabolic alkalosis
_____ 20/2 _____ 40/1 _____ 10/1 _____ 20/0.5
ANSWER: a, d, b, c
198.Indicate which type of acid-base imbalance might occur in each of the following situations by writing the appropriate letter in the blank. (a) respiratory acidosis
(b) respiratory alkalosis (c) metabolic acidosis (d) metabolic alkalosis
_____ fever
_____ excessive ingestion of alkaline drugs such as NaHCO3
_____ aspirin poisoning _____ anxiety
_____ severe exercise _____ uremia
_____ damage to the respiratory center _____ severe diarrhea
_____ pneumonia
ANSWER: b, d, b, b, c, c, a, c, a,
199.Indicate the [CO2] and [HCO3-] levels in each of
the following situations by placing the appropriate letter in the blank preceding the acid-base abnormality. An answer may be used more than once and not all answers need to be used. (a) [CO2] normal, [HCO3-] decreased below
normal
(b) [CO2] normal, [HCO3-] increased above normal
(c) [CO2] increased above normal, [HCO3-] normal
(d) [CO2] decreased below normal,[ HCO3-]
normal
(e) [CO2] decreased below normal, [HCO3-]
decreased below normal
(f) [CO2] increased above normal, [HCO3-]
increased above normal
(g) [CO2] decreased below normal, [HCO3-]
increased above normal
(h) [CO2] increased above normal, [HCO3-]
decreased below normal
(i) [CO2] normal, [HCO3-] normal
_____ uncompensated respiratory acidosis _____ compensated respiratory l acidosis _____ uncompensated metabolic acidosis _____ compensated metabolic acidosis _____ uncompensated respiratory alkalosis _____ compensated respiratory alkalosis _____ uncompensated metabolic alkalosis _____ compensated metabolic alkalosis
ANSWER: c, f, a, e, d, e, b, f
Completion
200.Complete each of the following statements with the word increases or decreases.
The secretion of ADH ________ the permeability of the nephron tubules to water.
The secretion of ADH _________ the reabsorption of water in the nephrons.
The release of free H+ into the blood _________
the pH of the blood.
If water is reabsorbed in the nephrons tubules the hypertonicity of the blood ________.
Consumption of a large amount of 100% water _________ the hypertonicity of the ECF.
The combination of free H+ with bicarbonate ions
in the blood _________ the pH of the blood.
ANSWER: increases, increases, decreases, decreases, decreases, decreases, increases
Questions 201 to 210 refer to the acid-base abnormality that would result from extensive pneumonia in which gas exchange is impaired. Indicate the correct answers by selecting the appropriate letter for each item.
201.If a patient has extensive pneumonia, before compensation occurs the patient’s PCO2 would be:
(a) decreased. (b) increased. (c) normal.
ANSWER: b
202.As a consequence of this change in PCO2, the
patient’s [H+] would be:
(a) decreased. (b) increased. (c) normal.
ANSWER: b
203.Therefore, the pH of the patient’s body fluids would be:
(a) below normal. (b) above normal. (c) normal.
ANSWER: a
204.Which of the following acid-base abnormalities would be present?
(a) Respiratory alkalosis. (b) Respiratory acidosis. (c) Metabolic alkalosis. (d) Metabolic acidosis.
ANSWER: b
205.Which of the following [HCO3-]/[CO2] ratios
might exist in this condition? (a) 20/5
(b) 20/2 (c) 40/1 (d) 10/1 (e) 20/1
ANSWER: b
206.Given the following logarithms, what would the pH be?
log of 20 = 1.3 log of 40 = 1.6 log of 10 = 1.0 pK = 6.1
(a) pH = 7.7 (b) pH = 7.4 (c) pH = 7.1
(d) none of these answers.
ANSWER: c
207.For which of the following reasons must this change in pH be restored to normal?
(a) If the acid-base abnormality is not corrected, the patient will experience muscle twitches, muscle spasms, “pins and needles” sensations, and may exhibit extreme nervousness and even convulsions.
(b) If the acid-base abnormality is not corrected, the patient may become disoriented and later comatose.
(c) K+ retention and cardiac arrhythmias can
occur.
(d) Both (a) and (c) above. (e) Both (b) and (c) above.
ANSWER: e
208.The first line of defense against this change in [H+] is the chemical buffer systems. What will be
the primary buffer system that will respond to this change?
(a) phosphate buffer system. (b) NH4+: NH3 buffer system.
(c) protein buffer system. (d) hemoglobin buffer system.
(e) carbonic acid: bicarbonate buffer system.
ANSWER: d
209.The second line of defense will be the respiratory mechanism of pH control. Which of the following statements concerning respiratory response in this situation is correct?
(a) The respiratory mechanism of pH control cannot occur in this situation.
(b) Faster, deeper respirations will occur to compensate for the change in [H+].
(c) Slower, shallower respirations will occur to compensate for the change in [H+].
210.The third line of defense will be the renal
mechanism of pH control. Which of the following renal compensations will occur in response to this condition?
(a) HCO3- excretion will increase.
(b) H+ excretion will increase.
(c) NH3 secretion is likely to occur.
(d) Both (b) and (c) above. (e) All of these answers.
ANSWER: d
Essay Questions
1. Describe the means by which the body regulates water content.
2. Describe how sodium and blood pressure balance are interconnected.
3. Describe how the body responds to a substantial drop in ECF pH.
4. Often patients experiencing sympathetically induced hyperventilation are told to breath in a paper bag. Why?
