5/6: Acid-base regulation by the kidney - Wilson

Question 1

state the HH equation

Answer 1

look at notes

Question 2

describe respiratory acidosis

Answer 2

hypoventilation
increased PCO2
pH less than 7.4

Question 3

describe respirtaory alkalosis

Answer 3

hyperventialation
decreased PCO2
pH above 7.4

Question 4

describe metabolic acidosis

Answer 4

loss of HCO3-

ph less than 7.4

Question 5

describe metabolic alkalosis

Answer 5

increase in HCO3- concentartion

pH greater than 7.4

Question 6

kidneys regulate H+ ________ and HCO3- _______

Answer 6

excretion

reabsorption

Question 7

H+ ions are removed by

Answer 7

binding to filtered buffers (H2PO4) or bidning to NH3

Question 8

elimination of HCO3- in urine is equivalent to..

Answer 8

adding H+ to body

Question 9

insertion of ATPase into luminal membrane of distal tubule is stimulated by…

Answer 9

low pH

high pH stimulates recycling of ATPase back to the cytoplasm

there is distal and proximal acidification – proximal uses gradient

distal uses ATPase to directly pump out H+

Question 10

where is bicarbonate reabsorbed?

Answer 10

nearly all is filtered but reabsorbed in proximal tubule (90%) and collecting duct (10%)

Question 11

true or false: reabsorption of HCO3- back from tubular lumen into filtrate is by simple transport

Answer 11

FALSE

H+ secreted into tubular lumen reacts with HCO3- in the filtrate to form carbonic acid

carbonic acid is converted to H20 and CO2 by carbonic anhydrase

H2O and CO2 diffuse back into renal tubular cell where they are formed back into carbonic acid by carbonic anhydrase

H+ is then secreted into tubular lumen and HCO3- is exported to blood with sodium

NET: movement of NaHCO3 from filtrate to blood

Question 12

action of B type intercalated cells of collecting tubule

Answer 12

polarity of membrane transporters can be reverese — can acitively secrete bicarbonate and reabsorb proton if needed (important in metabolic alkalosis)

Question 13

limiting urine pH

Answer 13

4.4.

why? H+ translocating ATPase now inhibited

Question 14

ability to excrete H+ as H2PO4 is limited by

Answer 14

• amount of HPO42- in filtrate

- requirement of body to retain phosphate

Question 15

for each newly-formed H2PO4- excreted in urine…

Answer 15

one H+ eliminated

one new HCO3- formed and added to blood

Question 16

measure of H+ excreted in urine as undissociated weak acid

Answer 16

titratable acid

Question 17

how is H+ excreted as NH4+

Answer 17

glutaminase converts glutamine to glutamate

glutamate converted to alpha-ketoglutarate and NH4+ by glutamate dehydrogenase (yields two HCO3- )

NET: excretion of protons into lumen and new molecules of HCO3- to blood

Question 18

normal ???

arterial PCO2
arterial pH
arterial bicarb
urinary titratable acid
urinary ammonium ion

Answer 18

40 torr
pH 7.35-7.45
24 mmol/L *** this is a calculated value
0-20 mmol/day
20-40 mEq/day

Question 19

normal anion gap

Answer 19

8-12 mEq-L

Question 20

equation for anion gap

Answer 20

sodium - (bicarb and chloride)

Question 21

metabolic acidosis produces ______ anion gap

Answer 21

large

there is so unmeasured anion

Question 22

difference between measure bicarb and bicard predicted by normal buffer slope at that pH

Answer 22

base deficit

Question 23

what happens to bicarb levels with acute respiratory acidosis?

Answer 23

slightly increased

compensated chronic respiratory acidosis has a greater increase in bicarb

Question 24

what is hyperchloremic/non-gap metabolic acidosis?

Answer 24

as bicarb goes down, chloride goes up so there is no anion gap

• occurs with gastrointestinal or renal loss o fHCO3-

Question 25

accidental ingestion of excess antacid medication –>

Answer 25

metabolic alkalosis

Question 26

salicylate intoxication –>

Answer 26

metabolic acidosis and respiratory alkalosis

• stimulate respiration and
  inhibit metabolic processes leading to increased acidic body production