1. What is the primary function of the kidneys in acid-base balance?
a) To excrete hydrogen ions
b) To absorb bicarbonate
c) To regulate pH by adjusting blood volume
d) To produce erythropoietin
Answer: b) To absorb bicarbonate
Explanation: The kidneys help maintain acid-base balance by reabsorbing bicarbonate (HCO3-) and excreting hydrogen ions (H+), which helps regulate the pH of the blood.
2. Which of the following ions is primarily secreted by the kidneys to regulate blood pH?
a) Sodium ions (Na+)
b) Potassium ions (K+)
c) Hydrogen ions (H+)
d) Calcium ions (Ca2+)
Answer: c) Hydrogen ions (H+)
Explanation: The kidneys secrete hydrogen ions into the urine to help lower blood acidity and maintain the blood’s normal pH level.
3. What is the normal pH range of human blood?
a) 7.0 to 7.4
b) 7.35 to 7.45
c) 6.8 to 7.2
d) 8.0 to 8.2
Answer: b) 7.35 to 7.45
Explanation: The normal pH of human blood is slightly alkaline, typically ranging from 7.35 to 7.45.
4. How do kidneys compensate for respiratory acidosis?
a) By excreting bicarbonate
b) By reabsorbing hydrogen ions
c) By increasing excretion of hydrogen ions
d) By secreting ammonia
Answer: c) By increasing excretion of hydrogen ions
Explanation: In response to respiratory acidosis, the kidneys compensate by increasing the excretion of hydrogen ions to reduce acidity in the blood.
5. What role does the enzyme carbonic anhydrase play in kidney acid-base balance?
a) It synthesizes bicarbonate ions
b) It converts carbon dioxide into carbonic acid
c) It secretes hydrogen ions into urine
d) It converts carbonic acid into carbon dioxide and water
Answer: b) It converts carbon dioxide into carbonic acid
Explanation: Carbonic anhydrase is crucial in converting carbon dioxide and water into carbonic acid (H2CO3), which dissociates into hydrogen ions and bicarbonate to regulate pH.
6. Which of the following is the primary buffer in the blood?
a) Phosphate buffer
b) Hemoglobin buffer
c) Bicarbonate buffer
d) Protein buffer
Answer: c) Bicarbonate buffer
Explanation: The bicarbonate buffer system is the primary buffering mechanism in the blood, helping to maintain a stable pH by balancing carbonic acid and bicarbonate ions.
7. What happens when the kidneys retain bicarbonate?
a) The blood becomes more acidic
b) The blood becomes more alkaline
c) The blood pH remains unaffected
d) The kidneys excrete more hydrogen ions
Answer: b) The blood becomes more alkaline
Explanation: When the kidneys retain bicarbonate, the blood becomes more alkaline by neutralizing excess hydrogen ions.
8. Which structure in the kidney is primarily involved in acid-base regulation?
a) Glomerulus
b) Proximal convoluted tubule
c) Loop of Henle
d) Distal convoluted tubule
Answer: b) Proximal convoluted tubule
Explanation: The proximal convoluted tubule is responsible for the majority of bicarbonate reabsorption, playing a key role in maintaining acid-base balance.
9. What is the effect of chronic renal failure on acid-base balance?
a) Increased bicarbonate reabsorption
b) Decreased hydrogen ion secretion
c) Increased acid secretion
d) Improved buffering capacity
Answer: b) Decreased hydrogen ion secretion
Explanation: In chronic renal failure, the kidneys lose the ability to secrete hydrogen ions, leading to acidosis due to the buildup of hydrogen ions in the blood.
10. Which of the following is the primary method by which kidneys help regulate pH in metabolic acidosis?
a) Reabsorption of sodium
b) Excretion of ammonia
c) Secretion of potassium
d) Excretion of bicarbonate
Answer: b) Excretion of ammonia
Explanation: In metabolic acidosis, the kidneys excrete ammonia to combine with hydrogen ions, helping to buffer and neutralize acid in the blood.
11. The kidneys help regulate blood pH by excreting which of the following?
a) Ammonia and bicarbonate
b) Hydrogen ions and potassium
c) Bicarbonate and chloride
d) Sodium ions and carbon dioxide
Answer: a) Ammonia and bicarbonate
Explanation: The kidneys excrete ammonia, which helps neutralize acids in the blood, and regulate bicarbonate levels to maintain pH balance.
12. How does the kidney respond during metabolic alkalosis?
a) By excreting bicarbonate
b) By reabsorbing hydrogen ions
c) By increasing ammonia production
d) By retaining carbon dioxide
Answer: b) By reabsorbing hydrogen ions
Explanation: During metabolic alkalosis, the kidneys compensate by reabsorbing more hydrogen ions and excreting bicarbonate to restore normal blood pH.
13. What is the result of the kidneys failing to compensate for respiratory acidosis?
a) Increased blood pH
b) Increased levels of carbon dioxide in the blood
c) Decreased blood bicarbonate levels
d) Decreased hydrogen ion excretion
Answer: b) Increased levels of carbon dioxide in the blood
Explanation: If the kidneys fail to compensate for respiratory acidosis, carbon dioxide accumulates in the blood, increasing its acidity.
14. Which condition can result from the kidneys’ inability to excrete enough hydrogen ions?
a) Respiratory acidosis
b) Metabolic alkalosis
c) Metabolic acidosis
d) Hypernatremia
Answer: c) Metabolic acidosis
Explanation: If the kidneys cannot excrete enough hydrogen ions, metabolic acidosis can occur, leading to a decrease in blood pH.
15. What is the role of phosphate buffer in the kidneys?
a) To buffer excess carbon dioxide
b) To buffer excess hydrogen ions
c) To aid in the reabsorption of glucose
d) To aid in the filtration of proteins
Answer: b) To buffer excess hydrogen ions
Explanation: The phosphate buffer system in the kidneys helps neutralize excess hydrogen ions, playing a role in maintaining pH balance.
16. In which part of the kidney is ammonia primarily produced for acid-base regulation?
a) Glomerulus
b) Proximal tubule
c) Loop of Henle
d) Distal tubule
Answer: b) Proximal tubule
Explanation: Ammonia is primarily produced in the proximal tubule of the kidney, where it helps to neutralize excess hydrogen ions.
17. Which of the following is NOT a direct function of the kidneys in acid-base balance?
a) Excretion of hydrogen ions
b) Reabsorption of bicarbonate
c) Reabsorption of sodium ions
d) Secretion of ammonia
Answer: c) Reabsorption of sodium ions
Explanation: While the kidneys do reabsorb sodium, it is not a primary function for acid-base regulation. The reabsorption of bicarbonate and secretion of hydrogen ions and ammonia are directly involved in maintaining pH.
18. What is the role of the carbonic acid-bicarbonate buffer system in the kidneys?
a) To increase sodium reabsorption
b) To regulate hydrogen ion secretion and bicarbonate reabsorption
c) To increase potassium secretion
d) To secrete hydrogen ions into the urine
Answer: b) To regulate hydrogen ion secretion and bicarbonate reabsorption
Explanation: The carbonic acid-bicarbonate buffer system helps maintain the acid-base balance by regulating hydrogen ion secretion and bicarbonate reabsorption in the kidneys.
19. Which of the following can cause a disturbance in acid-base balance?
a) Renal tubular acidosis
b) Dehydration
c) Hyperglycemia
d) High blood pressure
Answer: a) Renal tubular acidosis
Explanation: Renal tubular acidosis is a condition where the kidneys fail to secrete hydrogen ions effectively, disrupting acid-base balance.
20. What is the effect of kidney failure on the body’s ability to regulate pH?
a) It enhances the body’s ability to excrete hydrogen ions
b) It impairs the excretion of hydrogen ions and ammonia
c) It increases bicarbonate reabsorption
d) It maintains normal pH despite renal dysfunction
Answer: b) It impairs the excretion of hydrogen ions and ammonia
Explanation: Kidney failure can impair the kidneys’ ability to secrete hydrogen ions and ammonia, leading to an imbalance in blood pH, often resulting in acidosis.
21. How do kidneys regulate the blood’s bicarbonate levels?
a) By filtering excess bicarbonate into the urine
b) By synthesizing bicarbonate from carbon dioxide
c) By secreting bicarbonate into the bloodstream
d) By excreting bicarbonate in the urine
Answer: b) By synthesizing bicarbonate from carbon dioxide
Explanation: The kidneys help maintain blood bicarbonate levels by synthesizing bicarbonate from carbon dioxide, which is then reabsorbed into the bloodstream.
22. In acid-base regulation, how does the kidney assist during hypoventilation?
a) By increasing hydrogen ion excretion
b) By decreasing bicarbonate reabsorption
c) By retaining bicarbonate and excreting hydrogen ions
d) By increasing ammonia production
Answer: c) By retaining bicarbonate and excreting hydrogen ions
Explanation: During hypoventilation, there is an increase in CO2 in the blood, and the kidneys compensate by retaining bicarbonate and excreting more hydrogen ions to restore pH balance.
23. Which of the following is an important buffer in the kidneys’ response to acidosis?
a) Potassium buffer
b) Chloride buffer
c) Ammonium buffer
d) Phosphate buffer
Answer: c) Ammonium buffer
Explanation: The ammonium buffer system helps neutralize excess hydrogen ions, playing a significant role in the kidneys’ response to acidosis.
24. What happens to bicarbonate in response to increased acidity in the blood?
a) It is excreted in the urine
b) It is reabsorbed in the kidney
c) It is broken down into hydrogen ions
d) It is converted into carbonic acid
Answer: b) It is reabsorbed in the kidney
Explanation: In response to increased blood acidity, the kidneys reabsorb bicarbonate to help neutralize the hydrogen ions and restore pH balance.
25. Which of the following conditions is most likely to lead to metabolic acidosis?
a) Diarrhea
b) Vomiting
c) Respiratory alkalosis
d) Hyperventilation
Answer: a) Diarrhea
Explanation: Diarrhea leads to a loss of bicarbonate, which can cause metabolic acidosis due to the accumulation of hydrogen ions.
26. What is the kidney’s role in regulating acid-base balance during hyperventilation?
a) Increase secretion of bicarbonate
b) Decrease secretion of hydrogen ions
c) Increase production of ammonia
d) Increase reabsorption of bicarbonate
Answer: b) Decrease secretion of hydrogen ions
Explanation: During hyperventilation, the body loses carbon dioxide, causing a drop in blood acidity. The kidneys compensate by reducing hydrogen ion secretion.
27. What is the role of the distal convoluted tubule in acid-base balance?
a) Reabsorbing bicarbonate
b) Secreting hydrogen ions
c) Filtering ammonia
d) Producing erythropoietin
Answer: b) Secreting hydrogen ions
Explanation: The distal convoluted tubule secretes hydrogen ions into the urine, helping regulate acid-base balance in the blood.
28. Which of the following statements is true about kidney regulation of acid-base balance?
a) The kidneys regulate pH by secreting hydrogen ions into the urine and reabsorbing bicarbonate.
b) The kidneys excrete bicarbonate to lower blood pH.
c) The kidneys do not play a role in acid-base regulation.
d) The kidneys regulate pH by excreting ammonia and reabsorbing hydrogen ions.
Answer: a) The kidneys regulate pH by secreting hydrogen ions into the urine and reabsorbing bicarbonate.
Explanation: The kidneys help maintain acid-base balance by excreting hydrogen ions into the urine and reabsorbing bicarbonate.
29. Which condition results from the kidneys’ inability to excrete excess hydrogen ions?
a) Metabolic acidosis
b) Respiratory alkalosis
c) Metabolic alkalosis
d) Respiratory acidosis
Answer: a) Metabolic acidosis
Explanation: When the kidneys cannot excrete enough hydrogen ions, metabolic acidosis develops due to the accumulation of excess hydrogen ions in the blood.
30. Which of the following mechanisms helps the kidneys excrete excess hydrogen ions?
a) Secretion of bicarbonate
b) Secretion of ammonia
c) Reabsorption of sodium
d) Reabsorption of potassium
Answer: b) Secretion of ammonia
Explanation: The kidneys secrete ammonia, which binds to hydrogen ions, forming ammonium that is excreted in urine, helping to maintain the pH balance.
