Plasma Osmolality

Question 1

what detects a change in plasma osmolality

Answer 1

osmoreceptors

Question 2

where are osmoreceptors found

Answer 2

in the OVLT of the hypothalamus

Question 3

what responses are activated due to an increase in plasma osmolality

Answer 3

thirst response and ADH response

Question 4

when is the thirst response stimulated

Answer 4

when the plasma osmolality has increased by 10%

Question 5

what types of aqua porins are always found in the DCT and CD

Answer 5

types 3 and 4

Question 6

what does ADH do

Answer 6

increase the expression of aqua porin 2 channels in the DCT and CD

Question 7

on which membrane of the cells are aqua porin 2 channels found

Answer 7

apical membrane

Question 8

on which membrane side of the cells are aqua porins 3 and 4 channels founds

Answer 8

basolateral

Question 9

true or false: ADH causes diuresis

Answer 9

false - as water will be reabsorbed and not lost into the urine

Question 10

what is central diabetes insipidus

Answer 10

where theres too little ADH

Question 11

what causes central diabetes insipidus

Answer 11

hypothalamus injury, tumour, aneurysm

Question 12

how is central diabetes insipidus treated

Answer 12

oral ADH spray

Question 13

what osmolality changes in the plasma and urine will occur in central diabetes insipidus

Answer 13

high plasma osmolality

low urine osmolality

Question 14

what is nephrogenic diabetes insipidus

Answer 14

where problems with the kidneys mean they don’t respond to ADH

Question 15

what will the urine be like in diabetes insipidus

Answer 15

large volumes of dilute urine

Question 16

true or false: the thirst response will be activated in diabetes insipidus

Answer 16

true

Question 17

why do patients get polyuria in diabetes mellitus

Answer 17

as theres glucose not being reabsorbed and so left in the nephron tubules - this means more water stays in the tubules as the concentration gradient has decreased, so more water is lost in the urine

Question 18

why do patients get polydipsia in diabetes mellitus

Answer 18

as they are losing more water in the urine, their plasma osmolality increases activating the thirst response, making them drink more

Question 19

what does SIADH stand for

Answer 19

syndrome of inappropriate ADH

Question 20

what is SIADH

Answer 20

where too much ADH is released

Question 21

what happens to the plasma and urine osmolalities in SIADH

Answer 21

plasma - decrease

urine -increase

Question 22

describe the movement of urea in the nephron

Answer 22

goes through the ascending loop of henle, through the DCT and CD - then diffuses into the interstitum

Question 23

why is urea recycled in the nephron

Answer 23

to increase the concentration deep in the medulla

Question 24

through what channels does urea go through in the kidney when its being recycled

Answer 24

aqua porin channels

Question 25

true or false: urea recycling is ADH dependant

Answer 25

true - as the urea must travel through aqua porins

Question 26

what sets up the concentration gradient from the cortex to the medulla

Answer 26

the ascending limb of the loop of henle

Question 27

how does the loop of henle set up the concentration gradient in the cortex to medulla

Answer 27

the ascending limb transports salts out into the interstitum the salts causes water to move into the interstitum from the descending limb of the loop of henle the movement of salts and water helps to create the gradient

Question 28

what are the vasa recta

Answer 28

the blood vessels running parallel to the loop of henle of jutxamedullary nephrons

Question 29

what preserves the concentration gradient in the interstitum

Answer 29

vasa recta

Question 30

how does the vasa recta conserve the concentration gradient

Answer 30

by taking up the water lost from the descending limb so that it doesn't dilute the interstitum

Question 31

what is the concentration at the bottom of the medulla in the interstitum

Answer 31

1200 mOsm

Question 32

what is the concentration in the cortex/top of the interstitum

Answer 32

300 mOsm

Question 33

true or false: at the top of the interstitum, the osmolality is isotonic with plasma

Answer 33

true

Question 34

true or false: at the top of the ascending limb of the loop of henle, the osmolality is isotonic with plasma

Answer 34

false - it is actually hypotonic (100 mOsm)