Jan4 M1-Water balance

Question 1

ref phgy individual weight and body water

Answer 1

70kg. 60%. 42L

Question 2

how much fluid goes IV if give 1L water in IV compartment

Answer 2

83ml. 1/12

Question 3

body fluid compartments and values

Answer 3

IC: 8/12
IS: 3/12
IV: 1/12

Question 4

daily water intake and output value

Answer 4

2550 mL

Question 5

daily urine output and insensible losses

Answer 5

1500 mL urine. 900 mL insensible losses

Question 6

water in the PCT

Answer 6

(67%) NaK ATPase drives Na movement. Water follows (tight junctions and aquaporins)

Question 7

normal ECF osmolality (or osmolarity same thing)

Answer 7

275-290 mOsm/kg

Question 8

osmolality equation (blood)

Answer 8

Nax2 + urea + glucose = 275-290

Question 9

urea and alcohol osmotically active or inactive + def of that

Answer 9

urea: inactive (crosses cell membrane)
alcohol: active. add to equation if present

Question 10

ADH type of hormone + produced where and released where

Answer 10

peptide. group of hypothalamic neurons. released from posterior pituitary

Question 11

ADH acts how (exact names of receptors and proteins)

Answer 11

binds to V2 receptors in the collecting duct to stimulate the insertion of aquaporin-2 channels in the luminal membrane

Question 12

2 stimuli to ADH release and sensed where

Answer 12

hypertonicity, sensed by osmoreceptors in the hypothalamus

hypovolemia, sensed by carotid sinus. signals hypothalamus

Question 13

osmolality threshold for ADH release

Answer 13

290 or more

Question 14

how much water reabso at CD when no ADH and consequence

Answer 14

none. water diuresis. CD is impermeable to water

Question 15

diabetes insipidus pathophgy

Answer 15

malfunction of ADH system. ADH not released or doesn’t bind receptor. urine high in water

Question 16

DI can happen when

Answer 16

head injury or post neuro procedure

Question 17

2 main components of water regulation

Answer 17

permability to CD to water via ADH

high osm of medullary interstitium

Question 18

osmolality of the filtrate in Bowman’s space

Answer 18

same as blood (275-290)

Question 19

what nephrons do the high osm in the medullary interstitium and % they represent

Answer 19

juxtamedullary glomeruli (or corpuscules)

Question 20

% of juxtamedullary glomeruli vs not and loop of Henle in each

Answer 20

20% juxtamedullary: loop of Henle is in medulla + vasa recta with it
80% short loop of Henle and is in the cortex

Question 21

max urine osms

Answer 21

1400

Question 22

osms in diff parts of the nephron when ADH active vs when inactive

Answer 22

PCT: 300
DL: 600 to 1200
AL: 1200 to 100
DCT: 100
CT and CD: 300 to 1200. if no ADH, osm of 50 in CT and CD.

Question 23

tDL and TAL: what they are permeable to (most importantly)

Answer 23

tDL: water and not salt
TAL: salt and not water

Question 24

filtrate osms as enters DCT

Answer 24

100 mosm/L

Question 25

how filtrate osms goes from 1200 to 100 in AL

Answer 25

Na-Cl cotransporters pull Na and Cl into interstitium

Question 26

function of vasa recta and why the shape

Answer 26

take extra water and solutes back in the blood

shape avoids losses of solute gradient from interstitium

Question 27

2 portions of vasa recta and osms in them

Answer 27

descending limb of vasa recta: 300 to 1200

ascending limb of vasa recta: 1200 to 300

Question 28

vasa recta: what is the net reabsorption

Answer 28

only the water and solute net abso by the medullary tubules

Question 29

water reabso in %

Answer 29

67% PCT
15% tDL
0% in TAL and DCT
ADH for the rest in CT (CCD) and CD (MCD)

Question 30

furosemide site of action

Answer 30

inhibits Na-K-2Cl cotransporter in TAL by binding Cl site

Question 31

medullary interstitium and urine osmolality in patients on furosemide

Answer 31

300

Question 32

osms in different parts of the nephrons when on furosemide with ADH and without ADH

Answer 32

with and without ADH: 300 in all tubules

Question 33

why osms don’t increase in tDL when on furosemide

Answer 33

no osmotic gradient to pull water in interstitium