Physiology Spring L21 Acid Base 2

Front 1

What regulates respiration?

Back 1

this is regulated by plasma CO2- this works by increasing the level of H+ that is in the fluid near the medullary respiratory center

Front 2

What are the normal HCO3- levels?

Back 2

these are supposed to be between 22-26 mEq/L

Front 3

How do the kidneys stablize HCO3-? 3 ways

Back 3

complete reabsorption of HCO3- (when <26 mEq/L)

Synthesis of New HCO3-

excretion of HCO3- when present in excess.
(>26 mEq/L)

Front 4

What is the mechanism of HCO3- recovery

Back 4

This is drive by H+ secretion.
H+formed in the ICF by reaction of CO2 and water

H+ exchange for Na+ or actively secreted.

Requires carbonic anhydrase

This occurs in the proximal tubule

Front 5

Does HCO3- cross the apical membrane?

Back 5

no it does not

Front 6

How much filtered HCO3- is generally reabsorbed?

Back 6

99.9%

Front 7

Where does most bicarbonate recovery along the nerphon occur?

Back 7

this occurs in the proximal tubule

Front 8

What type of cells does bicarbonate recovery occur in the collecting duct?

Back 8

this occurs from Type A intercalated Cells

Front 9

What happens in the pertitubular capillary when an H+ is released into the proximal tubule/collecting duct?

Back 9

There is one HCO3- recovered into the ECF for every HCO3- that is neutralized by the H+ in the tubule

Front 10

When does H+ extrusion stop?

Back 10

when the luminal pH reaches 4.5

Front 11

Once the luminal pH hits 4.5, and no more HCO3 is present in the lumen, what is used to help pump out more H+

Back 11

this uses phosphate and NH4+ to unload additional H+

Front 12

How is bicarbonate made in the distal nephron?

Back 12

an ATPase pumps H+ out from bicarb formation in the collecting duct cell.

This now lumenal H+ binds to a "Buffer"

Buffer= titratable acidity and NH3

Front 13

What is titratable acidity?

Back 13

this is the phosphate that helps absorb the H+, once luminal HCO3- has run out.

this allows for more produciton of HCO3- in the renal tubular cells

Front 14

How does Glutamine result in the trapping of H+?

Back 14

In the proximal tubule, cells metabolize glutamine from blood.

this results in the production of Two HCO3- to the blood

and two NH4+ lost in urine

Front 15

What stimulates NH4 synthesis from glutamine?

Back 15

this is stimulated by Low blood pH.

results in the production of HCO3- to neutralize blood H+

Front 16

What is the primary mechanism of dealing with chronic acid load?

Back 16

this uses NH4 secretion from glutamine catabolism to produce HCO3- and help neutralize blood pH

Front 17

What is the rule for estimating Mass action?

Back 17

for every 10mmHg increase in Pco2, here is a 1mEq/L increase in HCO3-


and for every 10mmHg DECREASE in CO2, there is a 2mEq/L decrease in HCO3-

Front 18

What is the normal blood pH range?

Back 18

this is from 7.35 to 7.45