06.1 Acid-Base Balance

Question 1

How do the kidneys increase the plasma concentration of HCO3?

Answer 1

Reabsorbed all HCO3 filtered

Make more HCO3

Question 2

How do the kidneys make the majority of HCO3 and what happens to all of the products of the reaction?

Answer 2

Combine H20 with CO2(created as kidneys are highly metabolically active)
This produces H+ and HCO3-.
H+ enters the urine.
HCO3 enters the plasma.

Question 3

What is the other method HCO3 can be made in the kidneys?

Answer 3

From amino acids.

Produces NH4+ which is lost in the urine.

Question 4

Where is HCO3 created in the kidney?

Answer 4

DCT

Question 5

How is the excreted H+ buffered in the urine?

Answer 5

HPO4-

NH3

Question 6

What is the anion gap?

Answer 6

([Na]+[K])-([Cl]+[HCO3])

Question 7

What increases the anion gap?

Answer 7

In metabolic acidosis, H+ with HCO3- and the CO2 is breathed out. As HCO3- is replaced with the anion from the acid the anion gap becomes greater.

Question 8

In what situation would a metabolic acidosis not show an increase in the anion gap?

Answer 8

Certain renal problems can reduce HCO3- and replace it with Cl- so the anion gap stays the same.

Question 9

How do the tubular cells in the kidney respond to a metabolic acidosis?

Answer 9

The pH drop in tubular cells stimulates:
Acid secretion.
HCO3- recovery.

Question 10

What can cause a metabolic alkalosis?

Answer 10

Vomiting.

Question 11

What substance’s plasma concentration can a metabolic alkalosis cause to drop?

Answer 11

Ca2+

Question 12

How is plasma pH controlled?

Answer 12

The ratio of HCO3:pCO2
HCO3 Controlled by the kidneys
pCO2 Controlled by respiration