Lecture 19: Urine Concentration and Dilution

Question 1

When there is large excess of water in the body, kidneys can exert as much as ____ liters per day with a concentration as low as _____ mOsm/L

Answer 1

20; 50

Question 2

The ascending thick limb of Henle and late distal convoluted tubule are _____ to water

Answer 2

impermeable

Question 3

Kidney can produced a maximal urine concentration of ________

Answer 3

1200 to 1400 mOsm/L

Question 4

What is required to form a concentrated urine?

Answer 4

presence of ADH

high osmolarity of renal medullary interstitial tubule

Question 5

When there is an increase of ADH and cortical collecting tubule what happens?

Answer 5

water is reabsorbed from cortical collecting tubule

urea is not very permeant here and becomes more concentrated in tubule

Question 6

When there is a increase of ADH in the medullary collecting duct?

Answer 6

more water is reabsorbed form the duct, resulting in a higher concentration of urea
urea will diffuse out of duct into interstitial fluid

Question 7

What is obligatory urine volume?

Answer 7

0.5 L/ day

Question 8

Is the proximal tubule highly permeable to water?

Answer 8

yes

Question 9

Is the descending loop of henle highly permeable to water?

Answer 9

yes

Question 10

Is the thin ascending loop of henle permeable to water?

Answer 10

no

Question 11

Is the thick ascending loop of henle permeable to water?

Answer 11

no

Question 12

The thin ascending loop of henle reabsorbs ______

Answer 12

sodium chloride

Question 13

What are impermeable to urea?

Answer 13

ascending thick limb of henle and distal cortical collecting tubule

Question 14

What is the role of osmoreceptor ADH feedback mechanism

Answer 14

controls extraceullar fluid sodium concentration and osmolarity

Question 15

ADH is formed in magnocellular neurons in _____ and ______

Answer 15

supraoptic nuclei

paraventricualr nuclei