Session 1 - Renal Reabsorption

Question 1

what is the normal extracellular sodium concentrations

Answer 1

133-146 mM

Question 2

what is the normal extracellular potassium concentrations

Answer 2

3.5-5.3 mM

Question 3

what is the normal intracellular sodium concentrations

Answer 3

10-12 mM

Question 4

what is the normal intracellular potassium concentrations

Answer 4

140-155 mM

Question 5

what is the normal extracellular calcium concentrations

Answer 5

2.1-2.6 mM

Question 6

what is the normal intracellular calcium concentrations

Answer 6

10(-7) M

Question 7

what is the normal extracellular chloride concentrations

Answer 7

95-108 mM

Question 8

what is the normal intracellular chloride concentrations

Answer 8

4.2mM

Question 9

what is transcellular reabsorption

Answer 9

where substances move through the cell wall (e.g. through transporters)

Question 10

what is paracellular reabsorption

Answer 10

where substances move between cells due to concentration gradients

Question 11

what is the primary active transporter in the nephron

Answer 11

the sodium potassium ATPase

Question 12

what does the sodium potassium ATPase do

Answer 12

pump 3 sodium out and 2 potassium in

Question 13

where does sodium uptake in the nephron occur

Answer 13

in the ascending loop of Henle, distal convoluted tubule, collecting duct, proximal convoluted tubule

Question 14

how is sodium reabsorbed in the loop of Henle

Answer 14

NKCC2 - cotransporter transports sodium, potassium and chloride in

Question 15

how is sodium reabsorbed in the DCT

Answer 15

NCCT - sodium and chloride co transporter

ENaC - epithelial sodium channel

Question 16

what drug blocks NCCT

Answer 16

thiazides

Question 17

what drug blocks ENaC

Answer 17

amiloride

Question 18

how is sodium reabsorbed in the collected duct

Answer 18

ENaC

Question 19

what percentage of bicarbonate ions are reabsorbed in the kidneys

Answer 19

100%

Question 20

where is bicarbonate reabsorbed

Answer 20

proximal convoluted tubule

Question 21

describe bicarbonate reabsorption

Answer 21

the sodium hydrogen exchange allows sodium in and hydrogen out. the hydrogen combines to make carbonic acid which then splits into carbon dioxide and water. the carbon dioxide moves back into the luminal cell and helps form bicarbonate which is take. up by an anion exchanger

Question 22

how is water reabsorbed in the collecting duct

Answer 22

through aqua porins

Question 23

what hormone increases the expression of aqua porins

Answer 23

anti diuretic hormone

Question 24

what do diuretics do

Answer 24

block sodium reabsorption to give a loss of sodium and water in the urine

Question 25

how much sodium is reabsorbed

Answer 25

99%

Question 26

through what transporters is water reabsorbed

Answer 26

aqua porins

Question 27

what hormones controls the expression of aqua porins

Answer 27

anti diuretic hormone

Question 28

why can reabsorption occur in the nephron

Answer 28

the luminal and basolateral surfaces of the epithelia lining the tubules are polarised

Question 29

through which transporters is glucose absorbed into the epithelia from the lumen

Answer 29

sodium glucose transporter 2

Question 30

what transporter takes glucose from the epithelia to the blood

Answer 30

GLUT 2 transporters

Question 31

at what plasma glucose levels are the glucose transporter saturated

Answer 31

11 mmol/L

Question 32

what happens when all the glucose transporters are saturated

Answer 32

glucose is lost into the urine

Question 33

how is phosphate reabsorbed

Answer 33

through a sodium dependant transporter

Question 34

how are amino acid reabsorbed

Answer 34

through a sodium dependant transporter

Question 35

how is urea reabsorbed

Answer 35

through a sodium dependant transporter

Question 36

how is albumin reabsorbed

Answer 36

Receptor Mediated Endocytosis (RME)

Question 37

how are vitamins B12 and D3 reabsorbed

Answer 37

RME

Question 38

how is calcium reabsorbed

Answer 38

it enters the epithelia via a transporter that is upregulated by vitamin D in higher concentrations it can move paracellularly

Question 39

which part of the nephron reabsorbs the most sodium

Answer 39

PCT

Question 40

what channels are found in segment 1 of the PCT

Answer 40

NHE Na glucose symport Na-Pi co-transporter Na-AA co-transporter

Question 41

what is pressure natriuresis

Answer 41

where sodium is lost in the urine due to an increase in pressure

Question 42

what is pressure diuresis

Answer 42

where more water is lost in the urine due to an increase in pressure

Question 43

what transporters are found in segments 2 and 3 of the PCT

Answer 43

NHE

Question 44

what drug blocks NHE

Answer 44

amiloride

Question 45

what is reabsorbed in the descending limb of the loop of henle

Answer 45

water

Question 46

what transporters are found in the descending limb of the loop of Henle

Answer 46

aqua porins 2,3 and 4

Question 47

what is reabsorbed in the ascending limb of the loop of henle

Answer 47

sodium

Question 48

what channels are found in the ascending limb of the loop of henle

Answer 48

NKCC2 and ROMK

Question 49

what channels are in the early DCT

Answer 49

NaCl symporters

Question 50

what channels are found in the late DCT

Answer 50

ENaC

Question 51

what are NaCl sensitive to

Answer 51

thiazide diuretics

Question 52

what are ENaC sensitive to

Answer 52

amiloride

Question 53

what 2 cell types are found in the collecting duct

Answer 53

principal cells and intercalated cells

Question 54

what do principal cells do

Answer 54

reabsorb Na through ENaC channels

Question 55

what do intercalated cells do

Answer 55

secrete H+ or bicarbonate to alter blood pH

Question 56

what drives the movement of chloride ions throughout the nephron

Answer 56

the electrical gradient set up by the movement of sodium allows a passive paracellular movement of chloride