Deck 14: Acid-Base Balance

Question 1

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

A) Hydrochloric
B) Carbonic
C) Phosphoric
D) Lactic

Answer 1

B
Explanation: The only volatile acid of physiologic significance in the body is carbonic acid (H₂CO₃), which is in equilibrium with dissolved CO₂.

Question 2

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.

Answer 2

D
Explanation: The Henderson-Hasselbalch equation is useful for checking a clinical blood gas report to see if the pH, PCO₂, and [HCO₃^] values are compatible with one another.

Question 3

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

Answer 3

B
Explanation: To sustain life, the body must maintain the pH of fluids within a narrow range, from 7.35 to 7.45.

Question 4

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

A) Temperature rise of more than 3° 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 5

Which of the following are components of the body's nonbicarbonate buffer system?
1) Hemoglobin
2) Plasma proteins
3) Organic phosphates
4) Inorganic phosphates

A)1, 2, and 3 only
B)2 and 4 only
C)3 only
D)1, 2, 3, and 4

Question 6

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

A) Approximately the same amount
B) Less fixed than volatile
C) More fixed than volatile
D) CO₂ is not a volatile acid

Question 7

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.

Question 8

What is the primary buffer system for fixed acids?

A) Cl^-
B) HCO₃^-
C) Phosphate
D) Plasma proteins

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

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 11

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 12

Which buffer system has the greatest capacity?

A) Bicarbonate
B) Hemoglobin
C) Phosphates
D) Plasma proteins

Question 13

What are the major mechanisms responsible for maintaining a stable pH despite massive CO₂ production?
1) Isohydric buffering
2) Gastrointestinal secretion
3) Pulmonary ventilation

A)2 and 3 only
B)1 and 2 only
C)1, 2, and 3
D)1 and 3 only

Question 14

[H⁺] can be determined by the use of which factors?
1) HCO₃^-
2) H₂CO₃
3) Inorganic phosphorus
4) PaO₂

A)1, 2, and 3 only
B)2 and 3 only
C)4 only
D)1 and 2 only

Question 15

What effect does hyperventilation have on the closed buffer systems?

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

Question 16

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

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

Question 17

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

A) Carbohydrates
B) Fats
C) Proteins
D) Simple sugars

Question 18

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 19

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 20

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 21

Which organ system actually excretes H⁺ from the body?

A) Kidneys
B) Liver
C) Lungs
D) Spleen

Question 22

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

A) Ammonia
B) HCO₃^-
C) Hb
D) Phosphate

Question 23

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 24

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 25

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

A) Blood buffer system
B) GI tract
C) Renal system
D) Respiratory system

Question 26

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

A) Less H⁺ excretion, greater HCO₃^- loss
B) No effect 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 27

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 28

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

A)2 and 3 only
B)1, 2, and 3
C)3 only
D)1 and 2 only

Question 29

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 30

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

A)1, 2, and 3
B)1 and 3 only
C)2 only
D)2 and 3 only

Question 31

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

A) Liver
B) Lung
C) Renal
D) Spleen

Question 32

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 33

Which of the following mechanisms helps to eliminate excess H⁺ via the kidneys?
1) Reabsorption of HCO₃^-
2) Phosphate buffering
3) Ammonia buffering

A)2 and 3 only
B)1 and 3 only
C)2 only
D)1, 2, and 3

Question 34

Which of the following is/are true about the relationship between chloride (Cl^-) and bicarbonate HCO₃^- in acid-base balance?
1) For each Cl^- ion excreted into the urine, the blood gains an HCO₃^- ion.
2) Blood Cl^- and HCO₃^- ion levels are reciprocally related.
3) People with chronically high CO₂ tend to have low blood Cl^- levels.
4) Activation of the NH₃ buffer system enhances Cl^- gain and HCO₃ loss.

A)2 and 3 only
B)1, 2, and 3 only
C)2 only
D)2, 3, and 4 only

Question 35

In regard to acid excretion by the body, which of the following statements are true?
1) If one system fails, the other can help compensate.
2) The kidneys can only remove fixed acids.
3) The kidneys can quickly remove acid.
4) The lungs can quickly remove acid.

A)1, 2, and 4 only
B)2 and 3 only
C)4 only
D)1 and 4 only

Question 36

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 37

According to the Henderson-Hasselbalch equation, the blood pH will rise (alkalemia) under which of the following conditions?
1) The buffer capacity increases.
2) The volatile acid (CO₂) increases.
3) The volatile acid (CO₂) decreases.
4) The buffer capacity decreases.

A)1 only
B)3 only
C)1 and 3 only
D)2 and 4 only

Question 38

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 39

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

A) Hemoglobin
B) Inorganic phosphates
C) Organic phosphates
D) Plasma proteins

Question 40

Which of the following organ systems assist in acid excretion?
1) Kidneys
2) Liver
3) Lungs

A)3 only
B)1 and 3 only
C)2 only
D)1, 2, and 3

Question 41

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 42

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 43

Which of the following are potential causes of respiratory alkalosis?
1) Anxiety
2) Central nervous system depression
3) Hypoxemia
4) Pain

A)1, 2, and 3 only
B)1, 3, and 4 only
C)1 and 4 only
D)1, 2, 3, and 4

Question 44

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 45

Causes of respiratory acidosis in patients with normal lungs include which of the following?
1) Neuromuscular disorders
2) Spinal cord trauma
3) Anesthesia
4) Use of incentive spirometry

A)1, 2, and 3 only
B)4 only
C)2, 3, and 4 only
D)1 and 3 only

Question 46

How is acute respiratory acidosis accomplished?

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

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 the most common cause of respiratory alkalosis?

A) Anxiety
B) Central nervous system depression
C) Hypoxemia
D) Pain

Question 50

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 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 approximately 27 to 28 mmol/L.
C) HCO₃^- will fall to approximately 20 to 21 mmol/L.
D) HCO₃^- will rise to approximately 54 to 55 mmol/L.

Question 52

Which of the following clinical findings would you expect in a fully compensated respiratory acidosis?
1) Elevated HCO₃^-
2) pH below 7.35
3) pH between 7.35 and 7.39
4) Elevated PO₂

A)1 and 3 only
B)2 and 3 only
C)2 and 4 only
D)1, 3, and 4 only

Question 53

In the face of uncompensated respiratory acidosis, which of the following blood gas abnormalities would you expect to encounter?
1) Decreased pH
2) Increased HCO₃^-
3) Increased PCO₂
4) Increased pH

A)1, 2, and 4 only
B)1 and 3 only
C)3 only
D)2, 3, and 4 only

Question 54

A patient has a pH of 7.49. How would you describe this?

A) Acidemia
B) Alkalemia
C) Not sufficient information to determine
D) Normal acid-base status

Question 55

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 56

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 57

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 58

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 59

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 60

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 61

In a patient with Kussmaul's respirations, what acid-base disturbance would you expect to see?

A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis
D) Respiratory alkalosis

Question 62

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 63

Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.43, PCO₂ = 39 mm Hg, HCO₃^- = 25.1 mEq/L

A) Acid-base status within normal limits
B) Fully compensated metabolic acidosis
C) Fully compensated respiratory alkalosis
D) Partially compensated metabolic acidosis

Question 64

What is the main compensatory mechanism for metabolic acidosis?

A) Excretion of HCO₃^-
B) Hyperventilation
C) Hypoventilation
D) Retention of CO₂

Question 65

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

A)1 only
B)1 and 2 only
C)1, 2, and 3
D)1 and 3 only

Question 66

Which of the following are signs and symptoms of acute respiratory alkalosis?
1) Convulsions
2) Depressed reflexes
3) Dizziness
4) Paresthesia

A)1, 2, and 4 only
B)1, 3, and 4 only
C)2 and 4 only
D)1, 2, 3, and 4

Question 67

A patient who has fully compensated respiratory acidosis becomes severely hypoxic. If her lungs are not too severely 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 68

What compensates for a metabolic alkalosis?

A) Hyperventilation
B) Hypoventilation
C) Renal excretion of HCO₃^-
D) Renal retention of H⁺

Question 69

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

A)2 only
B)1 and 2 only
C)1 and 3 only
D)3 only

Question 70

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 71

What condition or treatment could cause iatrogenic respiratory alkalosis?

A) Central nervous system stimulation
B) Mechanical hyperventilation
C) Severe hypoxemia
D) Vagal stimulation

Question 72

Which of the following is/are cause(s) of metabolic alkalosis?
1) Diuretics
2) Hyperkalemia
3) Hypochloremia
4) Vomiting

A)1, 3, and 4 only
B)2 and 3 only
C)1, 2, and 4 only
D)2 only

Question 73

Which of the following is/are cause(s) of hyperchloremic metabolic acidosis?
1) Hyperalimentation
2) Methanol intoxication
3) Severe diarrhea
4) NH₄Cl administration

A)2 only
B)1 and 4 only
C)1, 3, and 4 only
D)1, 2, 3, and 4

Question 74

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

A) Gastric suction
B) High-salt diet
C) Discontinuing the patient's diuretics
D) Vomiting

Question 75

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 76

What is the treatment for severe metabolic acidosis?

A) Charcoal
B) Insulin
C) Glucose
D) NaHCO₃^- infusion

Question 77

What are some causes of metabolic acidosis with an increased anion gap?
1) Diarrhea
2) Ketoacidosis
3) Lactic acidosis
4) Renal failure

A)2 and 3 only
B)2 and 4 only
C)2, 3, and 4 only
D)1, 3, and 4 only

Question 78

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 79

What is the kidneys' most important function?

A) Acid-base balance
B) Chloride maintenance
C) HCO₃^- maintenance
D) Sodium maintenance

Question 80

In a patient with partially compensated respiratory alkalosis, which of the following blood gas abnormalities would you expect to encounter?
1) Decreased pH
2) Decreased HCO₃^-
3) Decreased PCO₂
4) Increased pH

A)1, 2, and 4
B)1 and 3
C)3 only
D)2, 3, and 4