MCQs on Renal Function, Acid-Base Balance & Acid Base Disorders: Biochemistry

The renal system covers the glomerular functiontubular functionacid-base homeostasis,  biochemical assessment,  and clinical correlations. The glomerulus is mainly involved in the filtration of the blood for the excretion of waste products while retaining most of the proteins. 
The renal tubules function in secretion, reabsorption, and excretion of electrolytes, ions, organic acids, and urea. The renal tubules help regulate the osmolality, volume, and pH of the blood. 

The physiological function of Kidney & Acid-Base Balance 
Multiple Choice Question

1) The normal arterial blood pH is approximately 7.4. 
Select the hydrogen ion concentration that corresponds to pH 7.4. (Hint: Use pH = log 1/[H+] )
a) 35 mEq/L
b) 40 mEq/L
c) 45 mEq/L
d) 50 mEq/L

2) The following are the primary system that regulates acid-base homeostasis. 
Which of the following is the most powerful regulatory mechanism?
a) Chemical buffer system
b) Protein buffer system
c) Respiratory mechanism
d) Renal mechanism

3) The following are the primary system that regulates acid-base homeostasis. 
Which of the following is the first acting regulatory mechanism?
a) Chemical buffer system
b) Protein buffer system
c) Respiratory mechanism
d) Renal mechanism

4) The bicarbonate buffer systems play a vital role in acid-base homeostasis. The body can easily interconvert the carbonic acid into bicarbonate ions or carbon dioxide to regulate and maintain the change in hydrogen ion concentration. 
Identify the equation that represents the relation of carbon dioxide and bicarbonate ions in the maintenance of blood pH
a) pH = 6.1 + log { HCO3-/[0.03 XPco2]}
b) pH = 6.8 + log { HCO3-/[0.03 XPco2]}
c) pH = 6.1 + log { HCO3-/[0.05 XPco2]}
d) None of the above

5) Identify the correct ratio of bicarbonate to carbon dioxide in the extracellular fluids under normal physiological conditions.
a) 16: 1
b) 20: 1
c) 24: 1
d) 28: 1

6) The respiratory system regulates the acid-base balance by controlling the carbon dioxide concentration in the extracellular fluid. 
Which of the following statement are false to the respiratory regulations?
a) Increase in ventilation eliminates CO2 from the extracellular fluid and reduces H+ concentration
b) Increase in ventilation eliminates CO2 from the extracellular fluid and increases H+ concentration
c) A decrease in ventilation increases CO2, thereby increasing hydrogen ion concentration in extracellular fluid
d) All of the above

7) Which of the following statement is true regarding the respiratory control of acid-base maintenance?
a) Increase in hydrogen ion concentration stimulates the respiratory system
b) The respiratory system can effectively correct the hydrogen ion concentration by 50% to 70%
c) The impairment of lung function in a condition such as emphysema increases the pCO2 concentrations
d) All of the above

8) What is the site of reclamation of bicarbonate?
a) Glomerulus
b) Proximal Tubules
c) Loop of Henle
d) Distal Tubules

9) Which of the following processes are true regarding reclamation of bicarbonate by the kidney tubules except?
a) The hydrogen ions are secreted into the renal tubules via Na+ H+ ATPase transporter
b)  The secreted hydrogen ion combines with bicarbonate to form carbonic acid.
c) The carbonic acid is converted into water and carbon dioxide and the CO2 diffuses into the cells
d) The process involves net reabsorption of one bicarbonate and secretion of one hydrogen ion

10) The second renal mechanism for the maintenance of acid-base homeostasis is the active secretion of a hydrogen ion from the distal tubules and collecting ducts. 
Which of the following statement is true regarding hydrogen ion secretion?
a)  The carbon dioxide in the intercalated cells is converted into hydrogen and bicarbonate involving carbonic anhydrase
b) The hydrogen ions secreted by the Na+/H+ pump in the intercalated cells  are sequestered as titrable acid (H2PO4) or ammonium ions for excretion
c) The bicarbonate from the intercalated cells returns to the circulation
d) All of the above

11) The Kidney contributes to acid-base balance by:
a) Secretion of ammonia
b) Reclamation of bicarbonate
c) Increased ketogenesis
d) Decreased CO2 uptake

12) Excess Carbon dioxide (CO2) found in the following non-compensated conditions
a) Metabolic acidosis
b) Metabolic alkalosis
c) Respiratory acidosis
d) Respiratory alkalosis

13) Which of the following buffer system is present at a high concentration inside the cells and serve as an effective intracellular buffer in our body?
a) Bicarbonate buffer system
b) Albumin buffer system
c) Ammonia buffer system
d) Phosphate buffer system

14) Which of the following condition has a normal anion gap?
a) Ketoacidosis
b) Lactic acidosis
c) Hyperchloremic metabolic acidosis
d) Uremia

15) Which of the following remain unchanged during metabolic acidosis without respiratory compensation?
a) Bicarbonate Ion
b) Hydrogen ion
c) Anion Gap
d) The partial pressure of carbon dioxide

16) In Renal tubular acidosis type I, which of the following statement is true?
a) Bicarbonate reabsorption is impaired
b) Hydrogen ion secretion is impaired
c) Urinary pH is acidic below 5.5
d) Aldosterone action is impaired.

17) Which of the following best describes the condition ketoacidosis?
a) metabolic acidosis with a high anion gap
b) metabolic acidosis with a normal anion gap
c) respiratory acidosis with a high anion gap
d) respiratory acidosis with a normal anion gap

18) A 10-year-old body develops severe diarrhea while traveling to India. The laboratory investigation revealed the following results:

Arterial blood pH = 7.25
Partial Pressure of carbon dioxide = 24 mmHg
Bicarbonate = 10 mEq/L
Normal anion gap
The correct diagnosis of this patient is..................................................?

a) metabolic acidosis
b) metabolic alkalosis
c) respiratory acidosis
d) respiratory alkalosis

19) Which of the following condition causes metabolic alkalosis?
a) Uncontrolled diabetes mellitus
b) Starvation
c) Excess alcohol
d) Excess Aldosterone

20) The difference between unmeasured anions and unmeasured cations is estimated as the anion gap. Select the correct anion gap when;
Sodium = 144 mEq/L
Potassium = 24 mEg/L
Chloride = 108 mEq/L

a) 10
b) 20
c) 30
c) 40


Multiple Choice Answers:
1-b) 40 mEq/L
2-d) Renal mechanism
3-a) Chemical buffer system
4-a) pH = 6.1 + log { HCO3-/[0.03 XPco2]}
5-b) 20: 1
6-b) Increase in ventilation eliminates CO2 from the extracellular fluid and increases H+ concentration
7-d) All of the above
8-b) Proximal Tubules
9-d) The process involves net reabsorption of one bicarbonate and secretion of one hydrogen ion
10-d) All of the above
11-b) Reclamation of bicarbonate
12-c) Respiratory acidosis
13-d) Phosphate buffer system
14-c) Hyperchloremic metabolic acidosis
 15-d) The partial pressure of carbon dioxide
16-b) Hydrogen ion secretion is impaired
17-a) metabolic acidosis with a high anion gap
18-a) metabolic acidosis: decreased Pco2 is a result of respiratory compensation
19-d) Excess Aldosterone
20-a) 10

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