Question 1

Which of the following best explains why maintaining arterial pH between 7.35 and 7.45 is critical for normal cellular function?

Accepted Answer

Because proteins rely on a specific three-dimensional shape that can be altered by changes in pH, affecting their function.

Question 2

A patient presents with a blood pH of 7.28, rapid breathing, and a history of kidney failure. Which acid-base disturbance is most likely, and what is the primary compensatory mechanism?

Accepted Answer

Metabolic acidosis; compensation by increased respiratory rate to lower $PCO_2$

Question 3

Which equation correctly represents the carbonic acid-bicarbonate buffer system in the body?

Accepted Answer

$CO_2 + H_2O \Leftrightarrow H_2CO_3 \Leftrightarrow H^+ + HCO_3^-$

Question 4

During intense exercise, which of the following best describes how the respiratory system helps maintain acid-base balance?

Accepted Answer

Increased respiration eliminates excess $CO_2$, reducing $H_2CO_3$ formation and preventing acidosis.

Question 5

Which buffer system is most important in the cytosol and kidney tubules, and what are its main components?

Accepted Answer

Phosphate buffer system; dihydrogen phosphate ($H_2PO_4^-$) and monohydrogen phosphate ($HPO_4^{2-}$)

Question 6

A patient with emphysema is likely to develop which acid-base disturbance, and what is the expected change in arterial $PCO_2$?

Accepted Answer

Respiratory acidosis; increased arterial $PCO_2$

Question 7

Which of the following best describes the role of hemoglobin in acid-base balance within systemic capillary beds?

Accepted Answer

Hemoglobin binds $H^+$ ions generated from $CO_2$ transport, helping buffer changes in pH.

Question 8

Which of the following scenarios is most likely to result in metabolic alkalosis?

Accepted Answer

Prolonged vomiting leading to loss of gastric acid

Question 9

If a patient ingests a large amount of sodium bicarbonate, which buffer system is primarily involved in neutralizing the excess base?

Accepted Answer

Carbonic acid-bicarbonate buffer system

Question 10

Which of the following best explains why the carbonic acid-bicarbonate buffer system is not effective at buffering changes in $PCO_2$?

Accepted Answer

Because both $CO_2$ and $H_2CO_3$ are part of the same equilibrium, so changes in $PCO_2$ directly affect both sides of the buffer equation.

Question 11

A climber rapidly ascends to high altitude and develops tingling and muscle spasms. Blood gas analysis shows increased pH, decreased $PCO_2$, and decreased $HCO_3^-$. What is the most likely diagnosis?

Accepted Answer

Respiratory alkalosis

Question 12

Which of the following best describes the compensation for metabolic acidosis?

Accepted Answer

Increased respiratory rate to decrease $PCO_2$

Question 13

Which chemical buffer system is most abundant in blood plasma and cytosol?

Accepted Answer

Protein buffer system

Question 14

A patient with prolonged diarrhea is at risk for which acid-base disturbance, and what is the primary mechanism?

Accepted Answer

Metabolic acidosis; loss of $HCO_3^-$ from the body

Question 15

Which of the following equations represents the phosphate buffer system in the kidney tubules?

Accepted Answer

$H_2PO_4^- \Leftrightarrow H^+ + HPO_4^{2-}$

Question 16

Which of the following is a direct effect of acidosis (blood pH < 7.35) on the nervous system?

Accepted Answer

Depresses synaptic transmission, leading to disorientation and possible coma.

Question 17

Which of the following best describes the role of the kidneys in acid-base balance?

Accepted Answer

They excrete fixed acids and can generate or secrete $HCO_3^-$ as needed.

Question 18

A patient is found to have increased arterial $PCO_2$, decreased pH, and increased $HCO_3^-$. Which acid-base disturbance and compensation are present?

Accepted Answer

Respiratory acidosis with renal compensation (increased $HCO_3^-$ reabsorption)

Question 19

Which of the following best explains why high-protein diets can lead to a tendency toward acidosis?

Accepted Answer

High-protein diets produce more acids than bases during metabolism.

Acid-Base Balance and Buffer Systems in Human Physiology

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