Acid Base Balance Part 2

Question 1

What are the renal mechanisms in acid base balance? (3)

Answer 1

1) HCO-3 handling
2) Urine acidification
3) Ammonia synthesis

Question 2

What is HCO-3 handling? and where does it occur? (2)

Answer 2

Bicarbonate handling is bicarbonate reabsorption
90 % proximal tubule
10% distal tubule

Question 3

What is urine acidification?
How is the phosphate buffer important?

Answer 3

-Alkaline salts converted into acid salts
(e.g Na2HPO4 –> NaH2PO4)
Phosphate buffer important to bind H+ ions for secretion
CO2 produced by metabolic process

Question 4

Which two renal mechanisms are involved in base conservation and what percentage respectively? (4)

Answer 4

Acidification of the urine - 25 %

Ammonia synthesis – 75 %

Question 5

Describe ammonia synthesis?

Answer 5

NH3 is formed by glutamine (membrane permeable)
Ammonium is impermeable

Question 6

What is the renal response to the acid-base disorder Acidosis? (4)

Answer 6

-Increase in H+ excretion
-Normal HCO-3 secretion
-Decrease in urine pH
-Increase in plasma pH

Question 7

What is the renal response to the acid-base disorder Alkalosis? (4)

Answer 7

-Decrease in H+ excretion
-Increase in HCO-3 secretion
-Increase in urine pH
-Decrease in plasma pH

Question 8

What happens in a respiratory acidosis? (3)

Answer 8

-CO2 elimination decreases
-Lung disease
-Emphysema, chronic bronchitis

Question 9

What is the renal compensation for respiratory acidosis? (3)

Answer 9

-Increase in H+ secretion
-Increase in HCO-3 reabsorption
-Rise pH but further rise in HCO-3

Question 10

What happens in a respiratory alkalosis? (3)

Answer 10

-CO2 elimination increases
-Hyperventilation
-Fear, stress, pain

Question 11

What is the renal compensation for respiratory alkalosis? (3)

Answer 11

-Decrease in H+ secretion
-Decrease in HCO-3 reabsorption
-Fall pH but further drop HCO-3

Question 12

What happens in metabolic acidosis? (3)

Answer 12

-Ingestion acid
-Loss of alkaline fluid
-Diarrhoea, cholera, diabetic ketoacidosis

Question 13

What is the respiratory compensation for a metabolic acidosis? (3)
And the renal correction? (2)

Answer 13

-Increase in respiratory rate
-Decrease in Arterial PCO2
-Increase in pH and drop PCO2

-Increase in H+ secretion
-Increase in HCO-3 reabsorption

Question 14

What happens in metabolic alkalosis? (3)

Answer 14

-Ingestion of alkaline fluid
-Loss of acid
-Vomiting

Question 15

What is the respiratory compensation for a metabolic alkalosis? (3)

Answer 15

-Decrease in respiratory rate
-Increase in Arteriole PCO2
-Decrease in pH and rise PCO2

Question 16

Describe the effects of mixed acid-base disorders?

Answer 16

-More than one primary acid-base disorder
-When same type the changes in pH add so is life threatening
-If opposite then ph change is subtracted and is mild, doenst cancel out but pH change is very small