[PHYSIO] URINE CONCENTRATION

Question 1

counter current multiplier system found in

Answer 1

loop of henle

Question 2

role of counter-current multiplier

Answer 2

builds up osmolarity in medullary interstitium by throwing NaCl into the interstitium

Question 3

counter current multiplier system: active or passive?

Answer 3

active

Question 4

counter current exchanger system found in

Answer 4

vasa recta

Question 5

counter current exchanger system role

Answer 5

1-maintains osmolarity of medullary interstitium by trapping salts

2-remove water from interstitium

Question 6

establishes osmotic equilibrium b/w tubular fluid & medullary interstitium

Answer 6

MCD

Question 7

MCD depends on

Answer 7

ADH & urea reabsorption

Question 8

counter current exchanger system: active or passive?

Answer 8

passive

Question 9

thin ascending limb of LH receives hypertonic fluid due to

Answer 9

H2O reabsorption in descending limb
urea enters descending limb

Question 10

role of thin ascending limb of LH in counter current multiplier system

Answer 10

passively diffuses NaCl to interstitium

Question 11

role of thick ascending limb of LH in counter current multiplier system

Answer 11

ACTIVELY pumps out NaCl via Na-K ATPase

Question 12

NaCl is pumped inside thick ascending limb of LH via

Answer 12

Na-K/2Cl cotransporter

Question 13

counter current exchanger system prevents removal of ___by blood

Answer 13

NaCl & urea

Question 14

urine concentration depends on

Answer 14

high interstitial osmolarity

Question 15

high interstitial osmolarity depends on

Answer 15

NaCl & urea salts

Question 16

vasa recta is permeable to

Answer 16

water & solutes

Question 17

sources of water in interstitial space

Answer 17

1-descending limb of LH
2-DCT & CD
3-descending limb of VR

Question 18

water handling of descending limb of VR

Answer 18

transports water into interstitium

Question 19

water handling of ascending limb of VR

Answer 19

absorbs water from interstitium and transports it back to circulation

Question 20

site of urea trapping

Answer 20

inner MCD

Question 21

permeability of MCD to urea depends on

Answer 21

ADH

Question 22

urea trapping contributes to interstitial osmolarity by

Answer 22

600 mOsm/L

Question 23

outer cortical portion of MCD permeability

Answer 23

permeable to H20
impermeable to urea
(in presence of ADH)

Question 24

inner medullary portion of MCD permeability

Answer 24

permeable to both H20 & Urea
(in presence of ADH)

Question 25

inner medullary portion of MCD permeability

Answer 25

permeable to both H20 & Urea
(in presence of ADH)

Question 26

effect of high protein diet on urine concentration

Answer 26

↑urea production
↑H2O reabsorption
↑osmolarity
↑urine concentration

Question 27

effect of high protein diet on urine concentration

Answer 27

↑urea production
↑H2O reabsorption
↑osmolarity
↑urine concentration

Question 28

passive reabsorption of urea occurs in?
under effect of?

Answer 28

-inner MCD
-ADH

Question 29

steps of urea cycle

Answer 29

1-passively diffuses from MCD to MI
2-passively enters descending limb of VR
-⤷ exits thru ascending limb
of VR
2- and passively enters descending limb of LH
⤷exits thru MCD

Question 30

why does drinking excess H20 cause loss of urea in urine

Answer 30

↓blood osmolarity
↓ADH
↓H2O reabsorption
↓MCD permeability to urea
↓passive urea reabsorp from MCD

Question 31

role of ADH in urine concentration

Answer 31

↑DCT &CD H2O permeability
↑ inner MCD urea permeability
VC efferent arteriole
⤷↓VR BF & ↓wash out of solutes
⤷↑Na reaching LH so ↑Na
reabsorption

Question 32

urine concentration can fail due to

Answer 32

1- diabetes insipidus
2-CRF
3-excessive medullary BF
4-diuretics
5-osmotic diuresis