Renal Acid-Base Regulation

Question 1

What is protein function highly sensitive to?

Answer 1

Hydrogen ions

Question 2

What is acid-base management focused primarily on?

Answer 2

Hydrogen ions

Question 3

Major blood buffer?

Answer 3

HCO3-

Question 4

What is the primary acute regulator of pH?

Answer 4

Ventilation via the carbonic anhydrase reaction

Question 5

What is the long-term regulator of pH?

Answer 5

The kidney

Question 6

What is the ratio we are looking at?

Answer 6

HCO3-/CO2

Question 7

What is the isohydric principle?

Answer 7

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

Question 8

Effect of acidic plasma on ventilation?

Answer 8

Increase in ventilation

Question 9

What does hypoventilation cause?

Answer 9

Primary respiratory acidosis

Question 10

What does hyperventilation cause?

Answer 10

Primary respiratory alkalosis

Question 11

What causes metabolic acidosis?

Answer 11

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

Question 12

What causes metabolic alkalosis?

Answer 12

A relative loss of fixed acids from the body

Question 13

What occurs in compensatory changes?

Answer 13

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

Question 14

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

Answer 14

1. ) To retrieve filtered and form new HCO3-

2. ) To retain and secrete the H+ filtered

Question 15

Where is HCO3- reabsorbed in the nephron?

Answer 15

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

Question 16

How is HCO3- reabsorbed?

Answer 16

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

Question 17

How is H+ secreted?

Answer 17

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

Question 18

Depletion of what stimulates NHE?

Answer 18

ANG-II
NE
Cortisol
K+

Question 19

What do alpha-intercalated cells do?

Answer 19

Acidify urine

Question 20

How do alpha-intercalated cells work?

Answer 20

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

Question 21

What effect does aldosterone have on alpha-intercalated cells?

Answer 21

Stimulated H+ secretion and HCO3 absorption

Question 22

What does long period of aldosteronism cause?

Answer 22

K+ depletion

Increased H+ secretion (alkalosis)

Question 23

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

Answer 23

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

Question 24

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

Answer 24

Addition of NH4+ to the tubular fluid

Question 25

What happens for each NH4+ excreted?

Answer 25

A new HCO3- is formed

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

What does chronic renal failure cause?

Answer 28

Metabolic acidosis

Question 29

How does chronic renal failure cause acid-base conditions?

Answer 29

Reduced excretion of phosphates and NH4+

Reduces plasma HCO3-