Renal Physiology: Acid Base Flashcards Preview

Physiology II > Renal Physiology: Acid Base > Flashcards

Flashcards in Renal Physiology: Acid Base Deck (32)
Loading flashcards...
1
Q

Blood Buffer pH equation…

A

pH = 6.1 + log [bicarb] / (0.03 x PCO2)

2
Q

A 1 unit change in pH indicates a ___-fold increase in hydrogen ion concentration

A

10x

3
Q

13,000 - 20,000 mEq/day of volatile acid is handled by ______ and excreted as_____

A

lungs as CO2

4
Q

Non-volatile, or fixed, acids are handled by…

A

the kidney

5
Q

What is responsible for 75% of fixed acid production?

A

methionine and cysteine catabolism forming sulfuric acid

6
Q

What are the primary intracellular buffers?

A

proteins

Phosphate

7
Q

Mass action rule notes that for every ________ increase in PCO2, bicarb will increase by _______

A

10 mmHg PCO2 increase

1 mEq/L bicarb increase

8
Q

Mass action rule notes that for every ________ decrease in PCO2, bicarb will decrease by _______

A

10 mmHg PCO2 decrease

2 mEq/L bicarb decrease

9
Q

What regulates respiration?

A

plasma PCO2

10
Q

By what 3 mechanisms do the kidneys keep bicarb steady between 22-26?

A

complete recovery of filtered bicarb when over 26

synthesis above GFR

Excretion when excess

11
Q

What drives bicarb recovery in the nephron?

A

secretion of hydrogen ions

12
Q

In the PT, H+ is __________ and in the DT H+ is ________

A

H+ - sodium exchange (NHE) in PT

Active secretion in DT

13
Q

Bicarbonate is most absorbed in the _____ (x%), then the _____ (x%), and then the _____ (x%)

A

PT (85%)

Ascending thick limb (10%)

Collecting duct (5%)

14
Q

What percent of filtered bicarb is reabsorbed?

A

99.9%

15
Q

What two hormones, when acting on the PT, increase bicarb reabsorption?

A

AT II

Aldosterone

16
Q

This hormone, when active in the PT:

increases expression of sodium-hydrogen exchanger, which pumps hydrogen from ICF to lumen, allowing Bicarb to be transported to the ECF via sodium cotransport

A

AT II

17
Q

This hormone, when active in the PT:

increases expression of H+ ATPase, which pumps hydrogen from ICF to lumen, allowing Bicarb to be transported to the ECF via sodium cotransport

A

Aldosterone

18
Q

What enzyme catalyzes the reaction of water and carbon dioxide to form hydrogen ions and bicarb?

A

carbonic anhydrase

19
Q

This hormone, when active in the alpha-intercalated cells of the CD:

Increases expression of the H+-ATPase which pumps hydrogen from ICF to lumen, allowing Bicarb to be transported to the ECF via chloride cotransport

A

aldosterone

20
Q

hydrogen ions leave the PT tubule cells by what two mechanisms?

A

Sodium - Hydrogen Exchanger

H+-ATPase

21
Q

Hydrogen ions leave the alpha intercalated cells of the CD by what two mechanisms?

A

H+-ATPase

H+-Potassium Exchanger

22
Q

Bicarb leaves the alpha intercalated distal tubule cell for reabsorption via what mechanism?

A

bicarb-chloride exchanger

23
Q

Bicarb leaves the tubule cell of the PT via what two mechanisms?

A

Sodium-Bicarb cotransport

Bicarb-chloride exchange

24
Q

for every bicarb neutralized in the tubule, ___ bicarb(s) is/are released into the PTC…

A

1

25
Q

luminal pH may drop as low as ____ once bicarb is absent from filtrate

A

4.5

26
Q

How is the kidney able to release more bicarb to the PTC than is present in the filtrate?

A

phosphate and NH3 accept H+ in the tubule to allow secretion of H+, and release of bicarb to PTC

27
Q

Describe the mechanism by which bicarbonate can be produced in the distal nephron…

A

H20 + CO2 –> Carbonic acid
(catalyzed by carbonic anhydrase)

In order for carbonic acid to enter the tubule, there must be a non-bicarb buffer (PO4, NH3)

H+ crosses apical border to tubule, binds with NH4+ or PO4, and bicarb free to enter PTC

28
Q

In the PT, Glutamine becomes ____ and _____ via glutaminase.

NH4+ splits to NH3 and hydrogen, they both diffuses to the lumen (together/separate?), where they are rejoined as NH4+

AKG is converted to ______, and is cotransported to the PTC with ______

A

AKG and NH4+

NH3 and H+ diffuse to lumen separately

AKG converted to bicarb

Cotransported with sodium

29
Q

1 glutamine will yield ___ bicarbs and ____ NH4+s

A

2

30
Q

What regulates synthesis of NH4+ from glutamine?

A

pH

31
Q

acidosis _____ glutamine catabolism…

A

increases

32
Q

What is the primary mechanism for dealing with chronic acid loads?

A

synthesis of NH4+ from glutamine