Ren Reg

Question 1

Osmolarity equation

Answer 1

Concentration x no. of dissociated particles (Osm/L)

Question 2

Body fluid distribution

Answer 2

2/3 intracellular fluid

1/3 extracellular fluid 
-1/4 intravascular (plasma)
-3/4 extra vascular 
—95% interstitial fluid
—5% transcellular fluid

Question 3

Reabsorption thin descending limb

Answer 3

Water (passive) 15%

Question 4

Reabsorption thick ascending limb

Answer 4

Sodium (active and passive)

Question 5

Reabsorption of PCT

Answer 5

67% water

Question 6

Reabsorption CD

Answer 6

Variable water

Question 7

Urea recycling

Answer 7

Urea transported out of CD through UT-A1 (through apical cell membrane) and UT-A3 (through basolateral cell membrane) into medullary interstitium
Urea either goes to vasa recta (UT-B1) or loop of Henle (UT-A2)

Question 8

Purpose of urea recycling

Answer 8

Increase osmolarity of interstitium

Urine concentration occurs
Urea excretion requires less water

Question 9

Vasopressin production

Answer 9

Hypothalamus

Question 10

Vasopressin storage

Answer 10

Posterior pituitary

Question 11

Factors affecting ADH production

Answer 11

Plasma osmolarity - positive 
Blood pressure -negative
Blood volume - negative 
Nausea - positive
Angiotensin II - positive 
Nicotine - positive 
Ethanol - negative 
Atrial natriuretic peptide - negative

Question 12

Mechanism of action for ADH

Answer 12

Bind to V2 receptor
Activates G protein signalling cascade
Activates adenylate cyclase and then protein kinase A
Increases secretion of aquaporin 2 channels in recycled form
Transported to apical cell membrane
Water flows through AQP 2 (apical cell membrane) and then AQP 3 and 4 (basolateral cell membrane) to be reabsorbed in blood

Question 13

ADH effect on aquaporin

Answer 13

AQP2 and 3 affected as required based on water intake

Question 14

Diuresis thick ascending limb

Answer 14

Increased dilute urine excretion
Sodium reabsorption
(3)Sodium (2)potassium ATPase pump, potassium chlorine symporter and chlorine channel out to create low sodium concentration within
Sodium potassium (2)chlorine symporter pump in down gradient

Question 15

Diuresis collecting duct

Answer 15

Sodium passive in

(3)Sodium (2)potassium ATPase out

Question 16

Antidiuresis effect

Answer 16

Thick ascending limb: Sodium potassium chlorine (2) symporter increase
DCT: Sodium chlorine symporter increase
Collecting duct: Sodium channel increase

Question 17

Role of kidney in acid base balance

Answer 17

Secretion and excretion of H+
Reabsorption of HCO3-
Production of new HCO3-

Question 18

Reabsorption of bicarbonate ion percentage

Answer 18

PCT - 80%
Ascending limb - 10%
DCT - 6%
Collecting duct - 4%

Question 19

Fluid leaving PCT into thin descending limb

Answer 19

Isoosmotic

Question 20

Fluid leaving thick ascending limb into DCT

Answer 20

Hypoosmotic

Question 21

Fluid leaving DCT into CD

Answer 21

Hypoosmotic

Question 22

Diuresis DCT

Answer 22

Sodium potassium ATPase pump and potassium chlorine symporter out
Sodium chlorine symporter in

Question 23

Reabsorption of bicarbonate in PCT

Answer 23

CO2 enter cell by diffusion from tubular fluid
With water through carbonic anhydrase, produce H+ and bicarbonate
H+ leaves to tubular fluid through sodium hydrogen antiporter or hydrogen ATPase
Bicarbonate is reabsorbed into blood through sodium bicarbonate symporter

Question 24

Reabsorption of bicarbonate in DCT and CD

Answer 24

Alpha intercalated cell (normal)

• proton ATPase pump or proton potassium ATPase pump H+ into tubular fluid
• chlorine bicarbonate antiporter pump bicarbonate into blood

Beta intercalated cell (acidosis)

• chlorine bicarbonate antiporter pump bicarbonate into tubular fluid
• proton ATPase pump H+ into blood

Question 25

Production of new bicarbonate in PCT

Answer 25

Glutamine gives two molecules of ammonium and glutamate, which turns to 2 bicarbonates and reabsorbed Ammonium exit through tubular fluid through sodium proton antiporter (substitute proton) or becomes ammonia and binds with proton in tubular fluid to become ammonium

Question 26

Production of new bicarbonate in DCT and CD

Answer 26

Alpha intercalated cell - hydrogen enters tubular fluid and neutralised by phosphate buffer system - gains one bicarbonate ion

Question 27

Metabolic acidosis characteristic

Answer 27

Decreased bicarbonate | Decreased pH

Question 28

Metabolic acidosis compensation

Answer 28

Increased ventilation | Increases bicarbonate reabsorption and production

Question 29

Metabolic alkalosis characteristic

Answer 29

Increased bicarbonate | Increased pH

Question 30

Metabolic alkalosis compensation

Answer 30

Decreased ventilation | Increased bicarbonate excretion

Question 31

Respiratory acidosis characteristic

Answer 31

Increased PCO2 | Decreased pH

Question 32

Respiratory acidosis compensation

Answer 32

Acute - intracellular buffer | Chronic - increases bicarbonate reabsorption and production

Question 33

Respiratory characteristic

Answer 33

Decreased PCO2 | Increased pH

Question 34

Respiratory alkalosis compensation

Answer 34

Acute - intracellular buffer | Chronic - decreased bicarbonate reabsorption and production