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Excretion as an example of homeostatic control

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Question 5

Spironolactone is a potassium-sparing diuretic drug used to treat hypertension (high blood pressure) by altering excretion processes in the kidney.

The following statements describe potential physiological mechanisms of spironolactone in the nephron:

  1. Spironolactone competitively binds to antidiuretic hormone (ADH) receptors on the collecting duct cells, preventing aquaporin channels from inserting into the luminal membrane.
  2. Spironolactone reduces the active reabsorption of Na+Na^+Na+ ions from the tubular filtrate in the distal convoluted tubule and collecting duct.
  3. The presence of more Na+Na^+Na+ ions in the filtrate lowers its water potential, reducing the osmotic reabsorption of water into the blood.

Which of the above statements explain(s) how spironolactone is able to reduce blood pressure?

A

1, 2 and 3

B

only 1 and 2

C

only 2 and 3

D

only 1

Markscheme

Excretion as an example of homeostatic control Questions

  1. A Level
  2. /Biology
  3. /Excretion as an example of homeostatic control

17 exam-style questions on OCR A A Level Biology Excretion as an example of homeostatic control. Each one has a worked solution and a mark scheme showing where the marks go.

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