Renal 4

Question 1

sources of H+ gain

Answer 1

from CO2 (oxidative metabolism or hypoventilation)
high protein diet
loss of bicarbonate in urine

Question 2

sources of H+ loss

Answer 2

loss of H+ in urine (excess secretion of H+ to exhaust all bicarbonate)

Question 3

primary buffer system of ECF

Answer 3

CO2/HCO3-

Question 4

buffering is tightly regulated because most – are altered by small pH changes

Answer 4

protein transport and enzyme reaction

Question 5

alkalosis H+ loss –

Answer 5

H+ loss exceeds gain

Question 6

acidosis H+ gain

Answer 6

H+ gain exceeds loss

Question 7

bicarbonate is – at the glomerulus

Answer 7

freely filtered

Question 8

bicarbonate is extensively reabsorbed along –

Answer 8

PT, ALH, cortical collecting ducts

Question 9

bicarbonate can be secreted along –

Answer 9

collecting ducts

Question 10

bicarbonate reabsorption is an active process but there are – at the luminal membrane

Answer 10

no bicarbonate transporter

Question 11

how is bicarbonate reabsorbed?

Answer 11

depends on secretion of H+ which combine in the lumen with filtered bicarbonate

Question 12

water + CO2 =

Answer 12

carbonic acid

Question 13

carbonic acid is immediately dissociated into –

Answer 13

bicarbonate and H+ ions

Question 14

HCO3- moves down its concentration gradient and into the interstitial fluid and blood by –

Answer 14

facilitated transporters

Question 15

as HCO3- moves into the interstitial fluid and blood, H+ are transported to –

Answer 15

tubular lumen

Question 16

H+ transporters

Answer 16

H+ ATPase, H+/K+ ATPase, Na+/H+ transporter

Question 17

secreted H+ combines with bicarbonate that was –

Answer 17

filtered at glomerulus

Question 18

is there a net change in bicarbonate?

Answer 18

no

Question 19

as long as there is sufficient bicarbonate, all secreted H+ will combine to form –

Answer 19

carbonic acid –> water and CO2

Question 20

what happens when filtered bicarbonate is completely exhausted and there is none to form carbonic acid?

Answer 20

H+ combines with other weak acids like phosphates and sulfates

Question 21

when H+ ions combine with other weak acids it then –

Answer 21

excreted in urine

Question 22

when H+ combines with other weak acids (nonbicarbonate) –>

Answer 22

net gain of bicarbonate in interstitial fluid and blood

Question 23

what happens to the [H+] in the plasma when H+ combines with other weak acids (nonbicarbonates)?

Answer 23

lowers [H+]

increased pH

Question 24

metabolism of – by tubular cells contribute new bicarbonate to blood

Answer 24

glutamine

Question 25

glutamine is metabolized in the cell to form

Answer 25

ammonium and bicarbonate

Question 26

how does glutamine move from the tubular filtrate to tubular epithelial cell?

Answer 26

Na-glutamine symporter

Question 27

glutamine can also be taken up into the cell from –

Answer 27

peritubular plasma

Question 28

how is ammonium (NH4+) secreted into the tubular lumen

Answer 28

Na-NH4+ antiporter

Question 29

what happens to the bicarbonate that was produced from glutamine?

Answer 29

moves into plasma

Question 30

what are two quantities that make up H+ excretion?

Answer 30

H+ secretion/excretion on nonbicarbonate buffers such as phosphate

glutamine metabolism with excretion

Question 31

excrete H+ =

Answer 31

add bicarbonate (law of mass action)

Question 32

ultimate kidney function

Answer 32

balance H+ gains and losses

Question 33

kidney will eliminate or add H+ by –

Answer 33

altering bicarbonate concentration

Question 34

kidney response to acidosis

Answer 34

add bicarbonate to plasma to increase pH

Question 35

kidney response to alkalosis

Answer 35

excrete bicarbonate to decrease pH