Kidneys

Question 1

(4) Use the diagram to help explain the body’s hormonal response to dehydration.

Answer 1

• (dehydration detected by) osmoreceptors/hypothala mus (1)
• pituitary gland (1)
• (releases more) ADH (1)

• ADH acts on the nephron/collecting
duct/tubules (1)

•	making the {collecting duct/tubules/nephron} 
more permeable (1) 

• so more water is reabsorbed (by the
body/blood) (1)

Question 2

(2) Calculate the mean ADH level in the people without diabetes insipidus

Answer 2

(5.2 + 2.8 + 4.9 + 3.5 =) 16.4
(1)
(16.4/4 =) 4.1

Question 3

(2) Suggest why there is a wide range of ADH levels in the people without
diabetes insipidus.

Answer 3

variation in human
population/different body sizes
(1)
hydration level (1)
salt intake (1)
drug influence (1)

Question 4

(1) ADH is a hormone released into the blood by the

Answer 4

pituitary gland

Question 5

(1) Suggest a symptom of diabetes insipidus

Answer 5

dehydration / thirst / increased

volume of urine

Question 6

(6) Explain the role of ADH in regulating the water content of the blood.

Answer 6

negative feedback
Hydration
 increased water/decreased salt in blood
 detected by hypothalamus
 acts on the pituitary gland
 decreased release of ADH
 decreased permeability of collecting duct/renal
tubules/nephron
 less re-absorption of water
 Increased volume of urine
Dehydration
 decreased water/increase salt in blood
 detected by hypothalamus
 acts on the pituitary gland
 increased release of ADH
 increased permeability of collecting duct/renal
tubules/nephron
 more re-absorption of water
 decreased volume of urine