Deck 12: Acid-Base Balance

Question 1

The most important of the blood buffers is/are

A)bicarbonate.
B)blood proteins.
C)hemoglobin.
D)platelets.

Answer 1

A

Question 2

Acids are defined as

A)molecules that release hydroxyl ions (OH^-).
B)molecules that release hydrogen ions (H⁺).
C)molecules that combine with hydrogen ions.
D)substances that raise the bicarbonate ion concentration of the solution.

Answer 2

B

Question 3

Muscle pH is generally

A)0.4-0.6 pH units lower than arterial pH.
B)0.4-0.6 pH units higher than arterial pH.
C)equal to blood pH.
D)None of the above answers are correct

Answer 3

A

Question 4

The respiratory system works in the regulation of acid-base balance by lowering

A)arterial PO₂.
B)arterial PCO₂.
C)blood levels of HCO₃.
D)None of the above answers are correct

Question 5

Which of the following track running events would have the greatest risk of acid-base disturbance?

A)marathon
B)100 meter sprint
C)800 meter run
D)10,000 meter run

Question 6

The first line of defense in protecting against pH change during exercise is

A)sodium bicarbonate levels in the blood.
B)hemoglobin levels in the blood.
C)intracellular buffers.
D)plasma bicarbonate.

Question 7

The most common and strongest acid produced in skeletal muscle during heavy exercise is ________________ acid.

A)phosphoric
B)lactic
C)acetoacetic
D)citric

Question 8

An increase in blood levels of carbon dioxide results in a decrease in blood pH because an increase in PCO₂

A)decreases H⁺ ion levels in the plasma.
B)promotes an increase in lactic acid production in the muscle.
C)reacts with water to form carbonic acid,which dissociates to release H⁺.
D)none of the above answers are correct.

Question 9

Which of the following is true of the pH of arterial blood?

A)The normal pH is 7.0.
B)A pH of 7.0 would be considered acidosis.
C)A pH of 7.0 would be considered alkalosis.
D)None of the above is true.

Question 10

Which of the following events occurs during exercise at work rates above 60-80% VO₂ max?

A)a decrease in plasma bicarbonate concentration
B)an increase in blood lactic acid concentration
C)a decrease in blood pH
D)All of the above answers are correct

Question 11

The ability of histidine to buffer hydrogen ions is because histidine contains

A)an ionizable group
B)a free carbon atom that accepts hydrogen ions
C)bicarbonate molecules
D)None of the above answers are correct

Question 12

Repeated bouts of high intensity exercise (e.g. ,interval training)can reduce arterial pH to levels as low as

A)7.3
B)7.2
C)7.1
D)None of the above answers are correct

Question 13

Which of the following statements about a buffer is correct?

A)a buffer resists pH change
B)a buffer removes hydrogen ions from solution
C)buffers often consist of a weak acid and its conjugate base
D)All of the above answers are correct

Question 14

Which of the following plays an important role in acid-base balance during exercise?

A)respiratory system
B)kidneys
C)increased production of bicarbonate in white blood cells
D)None of the above answers are correct

Question 15

Which of the following events are not primary sources of hydrogen ions during rigorous exercise?

A)ATP breakdown and release of hydrogen ions
B)Increased production of lactic acid
C)Aerobic metabolism of glucose resulting in the production of carbonic acid
D)anaerobic production of 3-phosphoglucose during glycolysis

Question 16

Hyperventilation at rest can result in ___________ due to ____________.

A)metabolic acidosis;increased blood levels of lactic acid
B)respiratory acidosis;increasing blood levels of carbon dioxide
C)alkalosis;decreased blood levels of carbon dioxide
D)None of the above answers are correct

Question 17

Sodium bicarbonate has been ingested by athletes in an attempt to improve performance by

A)increasing blood buffering capacity.
B)decreasing muscle lactate production.
C)stimulating pulmonary ventilation to increase oxygen transport.
D)increasing plasma volume.

Question 18

Which of the extracellular buffers contributes the most to the cell's buffering capacity?

A)bicarbonate
B)hemoglobin
C)extracellular proteins
D)all of the above contribute equally

Question 19

Metabolic acidosis can result from the overproduction of ketoacids,which can occur

A)during exercise.
B)in uncontrolled diabetes.
C)as a result of high levels of glucose metabolism.
D)all of the above answers are correct.

Question 20

Acidosis can occur due to

A)a decrease in the H⁺ concentration.
B)a loss of acids from the blood.
C)an accumulation of bases in the blood.
D)none of the above.

Question 21

The bicarbonate buffer system is involved in both intracellular buffering and blood buffering of hydrogen ions.

Question 22

The principal buffer against acidosis during exercise is intracellular phosphate groups.

Question 23

Using the Henderson-Hasselbalch equation,calculate the pH of blood given: pKa = 6.1
Blood concentration of carbonic acid = 1.2 mEq/L
Blood concentration of bicarbonate = 24 mEq/L
Your calculation reveals that the pH of blood is

A)7.2
B)7.3
C)7.4
D)None of the above answers are correct

Question 24

An increase in the hydrogen ion concentration in contracting skeletal muscle can impair performance by hydrogen ions competing with calcium ions for binding sites on troponin.

Question 25

One of the principal means by which the kidneys regulate acid-base balance is by increasing or decreasing the bicarbonate concentration of the blood.

Question 26

An example of a strong base is bicarbonate (HCO₃^-).

Question 27

A lack of the enzyme carbonic anhydrase would affect the ability of the body to both buffer the blood and to transport CO₂.

Question 28

Which of the following transporters in skeletal muscles are responsible for moving hydrogen ions across the sarcolemma?

A)sodium-hydrogen exchanger
B)monocarboxylate transporter
C)lactate transporter
D)Both A and B are correct

Question 29

According to the Henderson-Hasselbalch equation,the pH of a weak acid solution is determined by

A)ratio of the concentration of the acid in solution to the concentration of the base
B)ratio of the concentration of the base in solution to the concentration of the acid
C)the dissociation constant of bicarbonate
D)All of the above answers are correct

Question 30

Studies reveal that exercise training improves muscle buffering capacity.Which of the following exercise-induced changes is NOT responsible for training-induced improvements in muscle buffering capacity?

A)increased levels of carnosine in muscle fibers
B)increased muscle levels of citrate synthase
C)increased content of hydrogen ion transporters
D)None of the above answers are correct