Buffer and Acid-Base Balance

Question 1

The bicarbonate buffer system is most important in regulating the pH of:

A. Intracellular fluid

B. Extracellular fluid

C. Urine

D. Cerebrospinal fluid

Answer 1

B. Extracellular fluid

Question 2

The pH of a buffer solution is equal to the pKa when:

A. The weak acid concentration is zero

B. The conjugate base concentration is zero

C. The weak acid and conjugate base concentrations are equal

D. The solution is strongly acidic

Answer 2

C. The weak acid and conjugate base concentrations are equal

Question 3

The phosphate buffer system is most important in regulating the pH of:

A. Blood plasma

B. Intracellular fluid

C. Urine

D. Extracellular fluid

Answer 3

B. Intracellular fluid

Question 4

The protein buffer system is most important in regulating the pH of:

A. Blood plasma

B. Intracellular fluid

C. Urine

D. All of the above

Answer 4

D. All of the above

Question 5

The buffer capacity is highest when:

A. pH = pKa ± 1

B. pH = pKa ± 2

C. pH = pKa ± 0.5

D. pH = pKa ± 3

Question 6

Which of the following is an example of a weak acid?

A. HCl

B. H2SO4

C. CH3COOH

D. HNO3

Answer 6

C. CH3COOH

Question 7

The conjugate base of H2PO4- is:

A. H3PO4

B. HPO4^2-

C. PO4^3-

D. H2PO4

Answer 7

B. HPO4^2-

Question 8

The conjugate acid of HCO3- is:

A. CO2

B. H2CO3

C. H+

D. OH-

Answer 8

B. H2CO3

Question 9

Renal compensation for acid-base disturbances primarily involves:

A. Excretion of H+ and reabsorption of HCO3-

B. Excretion of HCO3- and reabsorption of H+

C. Excretion of CO2

D. Excretion of NH4+

Answer 9

A. Excretion of H+ and reabsorption of HCO3-

Question 10

The main site of bicarbonate reabsorption in the nephron is:

A. Proximal convoluted tubule

B. Distal convoluted tubule

C. Loop of Henle

D. Collecting duct

Answer 10

A. Proximal convoluted tubule

Question 11

The enzyme responsible for the formation of carbonic acid from CO2 and H2O is:

A. Carbonic anhydrase

B. Lactate dehydrogenase

C. Glutaminase

D. Aldolase

Answer 11

A. Carbonic anhydrase

Question 12

The major source of ammonium (NH4+) production in the kidney is:

A. Glucose

B. Glutamine

C. Lactate

D. Acetoacetate

Answer 12

B. Glutamine

Question 13

The formation of titratable acid in the kidney involves:

A. H+ binding to phosphate

B. H+ binding to bicarbonate

C. H+ binding to hemoglobin

D. H+ binding to albumin

Answer 13

A. H+ binding to phosphate

Question 14

The renal mechanism for excreting fixed acids is:

A. Formation of titratable acid and ammonium

B. Formation of bicarbonate

C. Formation of carbonic acid

D. Formation of lactic acid

Answer 14

A. Formation of titratable acid and ammonium

Question 15

The major adaptive response of the kidney to increased acid load is:

A. Increased bicarbonate reabsorption

B. Increased ammonium excretion

C. Increased phosphate excretion

D. Increased lactate excretion

Answer 15

B. Increased ammonium excretion

Question 16

The hormone that increases Na+ reabsorption and H+ excretion in the kidney is:

A. Insulin

B. Aldosterone

C. Cortisol

D. ADH

Question 17

The main site of ammonium production in the nephron is:

A. Proximal convoluted tubule

B. Distal convoluted tubule

C. Loop of Henle

D. Collecting duct

Answer 17

A. Proximal convoluted tubule

Question 18

The renal excretion of acids is achieved by combining H+ with:

A. Bicarbonate

B. Phosphate and ammonia

C. Glucose

D. Lactate

Answer 18

B. Phosphate and ammonia

Question 19

In metabolic acidosis, the compensatory response is:

A. Hyperventilation

B. Hypoventilation

C. Increased bicarbonate reabsorption

D. Decreased bicarbonate reabsorption

Answer 19

A. Hyperventilation

Question 20

In respiratory alkalosis, the compensatory response is:

A. Hyperventilation

B. Hypoventilation

C. Increased bicarbonate excretion

D. Decreased bicarbonate excretion

Answer 20

C. Increased bicarbonate excretion

Question 21

The primary buffer system in blood is:

A. Hemoglobin

B. Bicarbonate

C. Phosphate

D. Protein

Answer 21

B. Bicarbonate

Question 22

The chloride shift is important for:

A. Maintaining electrical neutrality during CO2 transport

B. Removing H+ in the body

C. Providing H+ in the bloodstream in exchange with Cl-

D. Protein transport

Answer 22

A. Maintaining electrical neutrality during CO2 transport

Question 23

The most common cause of metabolic acidosis is:

A. Diarrhea

B. Vomiting

C. Hyperventilation

D. Hypoventilation

Answer 23

A. Diarrhea