Group Teaching - Kidney Function

Question 1

If a patient is dehydrated, the filtrate present in which of these areas will have the highest osmolarity?

1. Bowman’s capsule
2. Tip of Loop of Henle
3. Before Distal Convoluted Tubule
4. Start of medullary collecting duct

Answer 1

Tip of Loop of Henle

Question 2

The urine samples of different patients were analysed using the urine osmolarity test. Whose sample is likely to have the highest osmolarity?

1. Patient with loss-of-function V2 receptor mutation
2. Patient suffering from central diabetes insipidus
3. Patient with loss-of-function UT-B1 urea transporter mutation
4. Patient suffering from hepatic cirrhosis

Answer 2

Patient suffering from hepatic cirrhosis

Question 3

An athlete after finishing their London Marathon run drank 2L of distilled water. Which of the following statement is correct about their body fluids?

1. Decrease in Extracellular Fluid (ECF) volume
2. Decrease in plasma osmolarity
3. Decrease in Intracellular Fluid osmolarity
4. Decrease in interstitial fluid volume

Answer 3

Decrease in plasma osmolarity

Question 4

The increase in plasma concentration of which solute will have no effect on ADH production?

1. Glucose
2. Urea
3. Salt
4. Ethanol

Answer 4

Urea

Question 5

Sodium excretion is very limited (less than 1% of filtered load) and several mechanisms exist to tightly regulate it. Increasing sodium excretion reduces water retention. Potassium excretion can vary over a very large range (from 1 to 80% of filtered load). Why doesn’t this variability in potassium excretion have a marked effect on water balance?

1. Potassium is only excreted in the distal nephron so there is no time for it to have an effect on osmolarity.
2. Potassium is a major intracellular ion, so the variability affects intra-cellular fluid volume not extracellular fluid volume.
3. The amount of potassium in the plasma and extracellular is much lower than the amount sodium so that variations in this amount are insufficient to have a marked effect on water balance.
4. Whilst the amount of potassium in the tubular fluid in the collecting duct varies its concentration does not so it does not affect osmolarity.

Answer 5

The amount of potassium in the plasma and extracellular is much lower than the amount sodium so that variations in this amount are insufficient to have a marked effect on water balance.

Question 6

Why do most diuretics increase potassium excretion?

1. They reduce the uptake of K⁺ by the Na/K/Cl transporter.
2. The increase in sodium in the distal nephron is exchanged for potassium in the collecting duct because of the change in membrane potential.
3. The increase in flow rate is detected in the collecting duct and directly stimulates potassium excretion.
4. They cause a rise in plasma pH and this stimulates potassium export.

Answer 6

The increase in flow rate is detected in the collecting duct and directly stimulates potassium excretion.

Question 7

Mr Holmes (65 years old, 75 Kg) is being treated with a loop diuretic and Mr Smith (66 years old, 74 Kg) with a thiazide diuretic for past 3 weeks (assume that the doses of the respective treatments allow an equivalent inhibition of [Na⁺] reabsorption). Both the individuals are drinking insufficient but equivalent amount of water. Which of the following statement is likely to be true?

1. Mr Holmes urine will have higher osmolarity than Mr Smiths.
2. Mr Holmes urine will have lower osmolarity than Mr Smiths.
3. Both Mr Holmes and Mr Smith’s urine will have similar osmolarity.
4. Information provided is insufficient to reach any logical conclusion.

Answer 7

Mr Holmes urine will have lower osmolarity than Mr Smiths.

Question 8

Ms S, a 25-year-old woman while trekking the Himalayas develops symptoms of dizziness and pain. Following data was collected for her: Blood pH = 7.6, [HCO₃^-] = 16mEq/L, PCO₂ = 25mmHg. Identify her acid-base disorder.

[Normal values: Blood pH = 7.4, [HCO₃^-] = 24mEq/L, PCO₂ = 40mmHg]

1. Metabolic alkalosis
2. Respiratory alkalosis
3. Metabolic acidosis
4. Respiratory acidosis

Answer 8

Respiratory alkalosis

Question 9

Ms L, a 25-year-old healthy woman on her holiday develops stomach infection with nausea and vomiting. Following data was collected for her: Blood pH = 7.1, [HCO³_-] = 16mEq/L, PCO² = 30mmHg. Identify the compensatory mechanism being used by her body.

[Normal values: Blood pH=7.4, [HCO³_-] = 24mEq/L, PCO² = 40mmHg]

1. Renal compensation – Reduced reabsorption of Bicarbonate ions
2. Renal compensation – Reduced excretion of ammonia and proton ions
3. Respiratory compensation – Hypoventilation
4. Respiratory compensation – Hyperventilation

Answer 9

Respiratory compensation – Hyperventilation

Question 10

Ms J, a 25-year-old woman with a history of asthma, on her holiday develops stomach infection with diarrhoea. Following data was collected for her: Blood pH = 7.1, [HCO₃^-] = 16mEq/L, PCO₂ = 45mmHg. Identify her acid-base disorder.

[Normal values: Blood pH = 7.4, [HCO₃^-] = 24mEq/L, PCO₂ = 40mmHg]

1. Metabolic acidosis
2. Respiratory acidosis
3. Mixed alkalosis
4. Mixed acidosis

Answer 10

Mixed acidosis