Urine Concentration and Volume

Question 1

What controls the total solute concentration of body fluids?

Answer 1

Kidneys

Question 2

What are the tools to regulate urine concentration and volume?

Answer 2

(1) Countercurrent flow
(2) Osmolarity gradient
(3) Urea
(4) Hormones (ADH, Aldosterone)
(5) Diuretics
(6) Cardiovascular baroreceptors

Question 3

What is ADH and what does it do?

Answer 3

ADH = antidiuretic hormone; inhibits urine output

Question 4

What is aldosterone and what does it do?

Answer 4

Hormone that manages water/blood volume; regulates Na+ and K+ by
(1) increasing Na+ reabsorption
(2) increasing K+ secretion

Question 5

How does urea help with concentration and volume?

Answer 5

Urea influences osmolarity. Increase in urea in the renal medulla increases osmolarity in this region.