Renal Acid-Base Regulation Flashcards Preview

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Flashcards in Renal Acid-Base Regulation Deck (29)
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1

What is protein function highly sensitive to?

Hydrogen ions

2

What is acid-base management focused primarily on?

Hydrogen ions

3

Major blood buffer?

HCO3-

4

What is the primary acute regulator of pH?

Ventilation via the carbonic anhydrase reaction

5

What is the long-term regulator of pH?

The kidney

6

What is the ratio we are looking at?

HCO3-/CO2

7

What is the isohydric principle?

All buffer in a common solution are in equilibrium with the same H+ concentration

8

Effect of acidic plasma on ventilation?

Increase in ventilation

9

What does hypoventilation cause?

Primary respiratory acidosis

10

What does hyperventilation cause?

Primary respiratory alkalosis

11

What causes metabolic acidosis?

Ingestion, infusion or production of a fixed acid (acid source other than HCO3-)

12

What causes metabolic alkalosis?

A relative loss of fixed acids from the body

13

What occurs in compensatory changes?

The opposite value will increase in order to make the ratio of HCO3-/CO2 normal but not necessarily normal values for either

14

What are the major acid-base functions of the kidneys?

1.) To retrieve filtered and form new HCO3-
2.) To retain and secrete the H+ filtered

15

Where is HCO3- reabsorbed in the nephron?

Proximal tubule (80%)
Thick ascending limb (10%)
Distal nephron (10%)

16

How is HCO3- reabsorbed?

First has to be broken down as CO2 and H20 absorbed through apical and resynthesized in the tubular cell and pumped out via Na/HCO3- pump

17

How is H+ secreted?

Inside tubular cells H2CO3 is broken down and H+ is pumped out while Na+ is pumped in (NHE)

18

Depletion of what stimulates NHE?

ANG-II
NE
Cortisol
K+

19

What do alpha-intercalated cells do?

Acidify urine

20

How do alpha-intercalated cells work?

Apical: H/K ATPase (excrete H+ and absorb K+)
Basolateral: pump out HCO3- and take in Cl- via

21

What effect does aldosterone have on alpha-intercalated cells?

Stimulated H+ secretion and HCO3 absorption

22

What does long period of aldosteronism cause?

K+ depletion
Increased H+ secretion (alkalosis)

23

What occurs when more H+ is filtered compared to HCO3-?

H+ is buffered by phosphate leading to an increased absorption of HCO3-

24

What provides the most important mechanism for generating new HCO3 during chronic acidosis?

Addition of NH4+ to the tubular fluid

25

What happens for each NH4+ excreted?

A new HCO3- is formed

26

What effect do glucocorticoids, A-II, Norepinephrine have on acid-base balance?

Stimulates Na-H exchanger in proximal tubule stimulating more H+ secretion

27

What affect do mineralocorticoids (such as aldosterone) have on acid-base balance?

Stimulates H+ secretion by increasing the apical H+-pump and the Cl-HCO3 exchanger, Na reabsorption in the collecting tubules and ducts and K+ depletion mechanism

28

What does chronic renal failure cause?

Metabolic acidosis

29

How does chronic renal failure cause acid-base conditions?

Reduced excretion of phosphates and NH4+
Reduces plasma HCO3-