Deck 13: Acid-Base Balance

Question 1

Which buffer system has the greatest capacity?

A)bicarbonate
B)hemoglobin
C)phosphates
D)plasma proteins

Answer 1

A

Question 2

Why is the bicarbonate buffer system considered an open buffer system?

A)As the major blood and body buffer system, it is open by definition.
B)It operates only in the extracellular fluid, avoiding cell closure.
C)Its acid (carbonic acid) is converted to CO₂ and removed.
D)Its chemical reactions occur very quickly.

Answer 2

C

Question 3

What affect does hyperventilation have on the closed buffer systems?

A)causes them to bind with more H⁺
B)causes them to release more H⁺
C)has no affect on them at all
D)increases the affinity of the closed buffer system

Answer 3

B

Question 4

Which of the following are components of the body's nonbicarbonate buffer system?
I)hemoglobin
II)plasma proteins
III)organic phosphates
IV)inorganic phosphates

A)I, II, and III
B)II and IV
C)III only
D)I, II, III, and IV

Question 5

A solution that resists large changes in pH upon addition of an acid or a base best describes which of the following?

A)acid-base excretor
B)buffer solution
C)catabolic regulator
D)homeostatic control

Question 6

Which of the following is a volatile acid of physiologic significance?

A)hydrochloric
B)carbonic
C)phosphoric
D)lactic

Question 7

When a strong acid is added to the bicarbonate buffer system, what is the result?

A)strong base and neutral salt
B)strong acid and neutral salt
C)weak acid and neutral salt
D)weak acid and basic salt

Question 8

By comparison, how much fixed acid is produced in any given period compared to the volatile acid CO₂?

A)about the same amount
B)less fixed than volatile
C)more fixed than volatile

Question 9

What is the sum of all blood buffers in 1 L of blood?

A)buffer base
B)base excess
C)standard bicarbonate
D)base deficit

Question 10

Fixed acids are produced primarily from the catabolism of which of the following?

A)carbohydrates
B)fats
C)proteins
D)simple sugars

Question 11

A patient has a PCO₂ of 80 mm Hg. What is the concentration of dissolved CO₂ (in mM/L) in the blood?

A)1.2 mmol/L
B)2.4 mmol/L
C)24 mmol/L
D)40 mmol/L

Question 12

Why is a buffer system such as phosphate considered a closed system?

A)All the components remain in the system.
B)It has limited utility in buffering acids.
C)Its ability to buffer volatile acids is incomplete.
D)Once its buffer level is established, it will never change.

Question 13

What is the normal arterial blood pH range?

A)7.25 to 7.35
B)7.35 to 7.45
C)7.45 to 7.55
D)7.55 to 7.65

Question 14

Which of the following statements about the equilibrium constant of an acid is true?

A)The equilibrium constant of a weak acid is large.
B)The equilibrium constant of a strong acid is small.
C)The equilibrium constant of a weak acid is small.
D)The more an acid ionizes, the smaller is the equilibrium constant.

Question 15

Of what use is the Henderson-Hasselbalch equation for a clinician?

A)It can guide therapeutic decision for critically ill patients.
B)It establishes the baseline values for buffer enhancement treatments.
C)Given H₂CO₃ and CO₂ values, the pH can be computed.
D)It allows validation of the reported values on a blood gas report.

Question 16

The primary goal of acid-base homeostasis is to maintain which of the following?

A)normal HCO₃^-
B)normal PCO₂
C)normal pH
D)normal PO₂

Question 17

What factor would limit the ability of the H₂CO₃/HCO₃^- buffer system to perform efficiently?

A)temperature rise of more than 3 ^$\circ$ C
B)inadequate amount of 2,3-DPG in the blood
C)increased production of nonvolatile acids
D)lungs failing to excrete adequate levels of CO₂

Question 18

[H⁺] can be determined by the use of which factors?
I.HCO₃^-
II.H₂CO₃
III.inorganic phosphorus
IV.PaO₂

A)I, II, and III
B)II and III
C)IV only
D)I and II

Question 19

What are the major mechanisms responsible for maintaining a stable pH despite massive CO₂ production?
I)isohydric buffering
II)gastrointestinal secretion
III)pulmonary ventilation

A)II and III
B)I and II
C)I, II, and III
D)I and III

Question 20

What is the primary buffer system for fixed acids?

A)Cl^-
B)HCO₃^-
C)phosphate
D)plasma proteins

Question 21

According to the Henderson-Hasselbalch equation, the blood pH will rise (alkalemia) under which of the following conditions?
I.The buffer capacity increases.
II.The volatile acid (CO₂) increases.
III.The volatile acid (CO₂) decreases.
IV.The buffer capacity decreases.

A)I
B)III
C)I and III
D)II and IV

Question 22

Acid excretion is shared by which of the following organ systems?
I)kidneys
II)liver
III)lungs

A)III only
B)I and III
C)II only
D)I, II, and III

Question 23

What affect does hyperventilation have on HCO₃^- recovery in the kidneys?

A)less H⁺ excretion, greater HCO₃^- loss
B)no affect as these involve two independent systems
C)vicious cycle of worsening alkalemia as hyperventilation stimulates increased HCO₃^-retention
D)escalating retention of other buffer bases along with HCO₃^-

Question 24

The majority of the acid the body produces in a day is excreted through the lungs as CO₂. What happens to the H⁺ ions?

A)They are bound to Hb.
B)They bind to phosphate.
C)They form carbamino compounds.
D)They bind to an OH-forming H₂O.

Question 25

According to the Henderson-Hasselbalch equation, the pH of the blood will be normal as long as the ratio of HCO₃^- to dissolved CO₂ is which of the following?

A)10:1
B)20:1
C)24:1
D)30:1

Question 26

Which of the following is FALSE about the relationship between chloride (Cl^-) and bicarbonate HCO₃^- in acid-base balance?

A)For each Cl ion excreted into the urine, the blood gains an HCO₃ ion.
B)Blood Cl^- and HCO₃^- ion levels are reciprocally related.
C)People with chronically high CO₂ tend to have low blood Cl^- levels.
D)Activation of the NH₃ buffer system enhances Cl^- gain and HCO₃ loss.

Question 27

Which of the following systems is primarily responsible for the buffering of fixed acids?

A)ammonia
B)HCO₃^-
C)Hb
D)phosphates

Question 28

Which of the following mechanisms helps to eliminate excess H⁺ via the kidneys?
I.reabsorption of HCO₃^-
II.phosphate buffering
III.ammonia buffering

A)II and III
B)I and III
C)II
D)I, II, and III

Question 29

Of the nonbicarbonate buffer systems, which one is the most important?

A)hemoglobin
B)inorganic phosphate
C)organic phosphates
D)plasma proteins

Question 30

The numerator of the Henderson-Hasselbalch (H-H) equation (HCO₃^-) relates to which of the following?

A)blood concentration of nonbicarbonate buffers
B)excretion of volatile acid by the lungs
C)renal buffering and excretion of fixed acids
D)respiratory component of acid-base balance

Question 31

In regard to acid excretion by the body, which of the following statements are true?
I .If one system fails, the other can help compensate.
II.The kidneys can only remove fixed acids.
III.The kidneys can quickly remove acid.
IV.The lungs can quickly remove acid.

A)I, II, and IV
B)II and III
C)IV only
D)I, II, III, and IV

Question 32

What drives the bicarbonate buffer systems enormous ability to buffer acids?

A)the fact that H₂CO₃ is a strong buffer
B)the Henderson-Hasselbalch equation
C)the large amounts of 2,3-DPG in red blood cells
D)ventilation continually removing CO₂ from system

Question 33

Which of the following acts as the "first-line" or immediate defense against the accumulation of H⁺ ions?

A)blood buffer systems
B)GI tract
C)renal system
D)respiratory system

Question 34

Which organ system maintains the normal level of HCO₃^- at 24 mEq/L?

A)liver
B)lung
C)renal
D)spleen

Question 35

If the blood PCO₂ is high, the kidneys will do which of the following?

A)excrete more H⁺ and reabsorb more HCO₃^-
B)excrete less H⁺ and reabsorb more HCO₃^-
C)excrete less H⁺ and reabsorb less HCO₃^-
D)excrete more H⁺ and reabsorb less HCO₃^-

Question 36

When does a state of alkalemia exist?
I.The HCO₃^-/CO₂ ratio exceeds 20:1
II.The blood pH exceeds 7.45.
III.The blood PCO₂ exceeds 54 mm Hg.

A)II and III
B)I, II, and III
C)III only
D)I and II

Question 37

What is the role of carbonic anhydrase in the kidneys?

A)It drives the recovery of HCO₃^- and excretion of H⁺.
B)It is the catalyst for the hamburger phenomenon.
C)It promotes the excretion of CO₂ in the urine.
D)It promotes the loss of fluids in congestive heart failure.

Question 38

Normally which of the following occur when the kidneys eliminate H⁺?
I .Sodium ions (and water) are reabsorbed.
II.HCO₃^- is reabsorbed in proportion to the H⁺ excreted.
III.Bicarbonate buffer capacity is restored.

A)I, II, and III
B)I and III
C)II only
D)II and III

Question 39

Which organ system actually excretes H⁺ from the body?

A)kidneys
B)liver
C)lungs
D)spleen

Question 40

What is the limiting factor for H⁺ excretion in the renal tubules?

A)excessive amounts of Cl^-
B)excessive amounts of HCO₃^-
C)insufficient buffers
D)insufficient sodium

Question 41

An increase in the H⁺ ion concentration [H⁺] of the blood due only to an increase in the arterial PCO₂ (hypercapnia) best describes which of the following?

A)metabolic acidosis
B)metabolic alkalosis
C)respiratory acidosis
D)respiratory alkalosis

Question 42

A patient has a pH of 7.49. What would this define?

A)acidosis
B)alkalosis
C)not sufficient information
D)normal acid-base status

Question 43

In the face of uncompensated respiratory acidosis, which of the following blood gas abnormalities would you expect to encounter?
I.decreased pH
II.increased HCO₃^-
III.increased PCO₂
IV.increased pH

A)I, II, and IV
B)I and III
C)III only
D)II, III, and IV

Question 44

Correction of acute respiratory acidosis is accomplished by which of the following?

A)increasing HCO₃^-reabsorption
B)increasing alveolar ventilation
C)decreasing HCO₃^-reabsorption
D)decreasing alveolar ventilation

Question 45

Compensation for metabolic acidosis occurs through which of the following?

A)increase in blood CO₂ levels
B)decrease in blood CO₂ levels
C)decrease in blood HCO₃^- levels
D)increase in blood HCO₃^- levels

Question 46

Compensation for respiratory acidosis occurs through which of the following?

A)decrease in blood CO₂ levels
B)decrease in blood HCO₃^- levels
C)increase in blood CO₂ levels
D)increase in blood HCO₃^- levels

Question 47

Which of the following accurately describes compensation for acid-base disorders?

A)Kidneys take hours to days to compensate for respiratory disorders.
B)Lungs take hours to days to compensate for metabolic disorders.
C)Renal compensation is always complete.
D)Respiratory compensation is always complete.

Question 48

A patient has a bicarbonate concentration of 36 mEq and a PCO₂ of 60 mm Hg. What is the approximate pH?

A)7.2
B)7.3
C)7.4
D)7.5

Question 49

What is a normal response of the body to a failure in one component of the acid-base regulatory mechanism?

A)autoregulation
B)compensation
C)correction
D)homeostasis

Question 50

Causes of respiratory acidosis in patients with normal lungs include which of the following?
I)neuromuscular disorders
II)spinal cord trauma
III)anesthesia
IV)central nervous system depression

A)I, II, III, and IV
B)III
C)II, III, and IV
D)II and IV

Question 51

A patient with a measured plasma HCO₃^- concentration of 24 mmol/L has an episode of acute hypoventilation, with the PCO₂ rising from 40 to 70 mm Hg. What do you predict will happen acutely to the plasma HCO₃^- concentration?

A)HCO₃^-will remain unchanged.
B)HCO₃^- will rise to about 27 to 28 mmol/L.
C)HCO₃^- will fall to about 20 to 21 mmol/L.
D)HCO₃^- will rise to about 54 to 55 mmol/L.

Question 52

A decrease in the H⁺ ion concentration [H⁺] of the blood caused by a low PaCO₂ best describes which of the following?

A)metabolic acidosis
B)metabolic alkalosis
C)respiratory acidosis
D)respiratory alkalosis

Question 53

An ABG result shows pH of 7.35, PaCO₂ of 30 mm Hg, and HCO₃^- of 18 mEq/L. What compensatory measure has the body taken to at least partially compensate for the acid-base disorder?

A)blown off CO₂
B)retained HCO₃^-
C)retained H⁺
D)not enough information to determine

Question 54

What is the most common cause of respiratory alkalosis?

A)anxiety
B)central nervous system depression
C)hypoxemia
D)pain

Question 55

Which of the following clinical findings would you expect in a fully compensated respiratory acidosis?
I.elevated HCO₃^-
II.pH below 7.35
III.pH between 7.35 and 7.39
IV.elevated PO₂

A)I and III
B)II and III
C)II and IV
D)I, III, and IV

Question 56

An ABG result shows the pH to be 7.56 and the HCO₃^- to be 23 mEq/L. Which of the following is the most likely disorder?

A)metabolic acidosis
B)metabolic alkalosis
C)respiratory acidosis
D)respiratory alkalosis

Question 57

What is the primary chemical event in metabolic alkalosis?

A)decrease in blood CO₂ levels
B)decrease in blood HCO₃^- levels
C)increase in blood CO₂ levels
D)increase in blood HCO₃^- levels

Question 58

An ABG result shows pH of 7.35, PaCO₂ of 30 mm Hg, and HCO₃^-of 18 mEq/L. Which of the following is the patient's most likely primary disorder?

A)metabolic acidosis
B)metabolic alkalosis
C)respiratory acidosis
D)respiratory alkalosis

Question 59

What is the primary chemical event in respiratory acidosis?

A)decrease in blood CO₂ levels
B)decrease in blood HCO₃^- levels
C)increase in blood CO₂ levels
D)increase in blood HCO₃^- levels

Question 60

Which of the following are potential causes of respiratory alkalosis?
I)anxiety
II)central nervous system depression
III)hypoxemia
IV)pain

A)I, II, and III
B)I, III, and IV
C)I and IV
D)I, II, III, and IV

Question 61

Which of the following is NOT a cause of hyperchloremic metabolic acidosis?

A)hyperalimentation
B)methanol intoxication
C)severe diarrhea
D)NH₄Cl administration

Question 62

Compensation for respiratory alkalosis occurs through which of the following?

A)renal excretion of H⁺
B)renal excretion of HCO₃^-
C)renal excretion of NH₄⁺
D)renal reabsorption of HCO₃^-

Question 63

What compensates for a metabolic alkalosis?

A)hyperventilation
B)hypoventilation
C)renal excretion of HCO₃^-
D)renal retention of H⁺

Question 64

What is the treatment for severe metabolic acidosis?

A)charcoal
B)insulin
C)mechanical ventilation
D)NaHCO₃^- infusion

Question 65

A patient who has fully compensated respiratory acidosis becomes severely hypoxic. If her lungs are not too compromised, what might her gases now appear to be?

A)fully compensated metabolic acidosis
B)fully compensated metabolic alkalosis
C)fully compensated respiratory alkalosis
D)no change

Question 66

What are some causes of metabolic acidosis with an increased anion gap?
I)diarrhea
II)ketoacidosis
III)lactic acidosis
IV)renal failure

A)II and III
B)II and IV
C)II, III, and IV
D)I, III, and IV

Question 67

What condition or treatment could cause iatrogenic respiratory alkalosis?

A)central nervous system stimulation
B)mechanical hyperventilation
C)severe hypoxemia
D)vagal stimulation

Question 68

Which of the following is NOT a cause of metabolic alkalosis?

A)diuretics
B)hyperkalemia
C)hypochloremia
D)vomiting

Question 69

Primary metabolic alkalosis is associated with which of the following?

A)gain of buffer base
B)gain in fixed acids
C)low blood CO₂ levels
D)diabetic crisis

Question 70

Discounting K⁺, what is a normal anion gap range?

A)3 to 5 mEq/L
B)6 to 8 mEq/L
C)9 to 14 mEq/L
D)24 to 26 mEq/L

Question 71

A patient has a confirmed metabolic acidosis with a normal PCO₂. What inference can you draw from these findings?

A)A ventilatory disorder must coexist.
B)Compensation for the acidosis has begun.
C)The patient is hyperventilating.
D)The values obtained must be in error.

Question 72

Metabolic acidosis may be caused by:
I.an increase in fixed (nonvolatile) acids
II.an increase in blood carbon dioxide (CO₂)
III.excessive loss of bicarbonate (HCO₃^-)

A)I
B)I and II
C)I, II, and III
D)I and III

Question 73

What is the kidneys' most important function?

A)acid-base balance
B)chloride maintenance
C)HCO₃^-maintenance
D)sodium maintenance

Question 74

A patient with Kussmaul's respirations most likely has:

A)metabolic acidosis
B)metabolic alkalosis
C)respiratory acidosis
D)respiratory alkalosis

Question 75

What explains the lack of an increased anion gap seen in metabolic acidosis caused by HCO₃^- loss?

A)For each HCO₃^- ion lost, a Cl^- ion is reabsorbed by the kidney.
B)For each HCO₃^- ion lost, the body produces another to replace it.
C)HCO₃^- is not a measured anion, so its loss does not affect the anion gap.
D)Replacement of HCO₃^- occurs by ammonia ions which are also anions.

Question 76

What is the main compensatory mechanism for metabolic acidosis?

A)excretion of HCO₃^-
B)hyperventilation
C)hypoventilation
D)retention of CO₂

Question 77

With partially compensated respiratory alkalosis, which of the following blood gas abnormalities would you expect to encounter?
I.decreased pH
II.decreased HCO₃^-
III.decreased PCO₂
IV.increased pH

A)I, II, and IV
B)I and III
C)III only
D)II, III, and IV

Question 78

Which of the following is NOT a clinical sign of acute respiratory alkalosis?

A)convulsions
B)depressed reflexes
C)dizziness
D)paresthesia

Question 79

What would be an example of an iatrogenic cause of metabolic alkalosis?

A)gastric suction
B)hypochloremia
C)hypokalemia
D)vomiting

Question 80

A patient has an anion gap of 21 mEq/L. Based on this information, what can you conclude?
I.There is an abnormal excess of unmeasured anions in the plasma.
II.The patient probably has metabolic acidosis.
III.The concentration of fixed acids is increased.

A)II and III
B)I and II
C)I and III
D)I, II, and III