Acid-Base balance

Question 1

How does starvation case a metabolic acidosis?

Answer 1

Compensate with keto acid metabolism - produces acid

Question 2

What is the normal pH of the body?

Answer 2

7.4

Question 2

How can the kidneys respond to a metabolic alkalosis?

Answer 2

Decrease bicarbonate reabsorption and production

Decrease H+ excretion

Question 3

How does chronic diarrhoea cause metabolic acidosis?

Answer 3

Chronic loss of bicarbonate

Question 3

What of the following would be associated with high HCO3-

• Metabolic alkalosis
• Metabolic acidosis
• Respiratory alkalosis
• Respiratory acidosis

Answer 3

Metabolic alkalosis- HCO3- is the primary cause of the problem

Respiratory acidosis - HCO3- is high to compensate

Question 3

What are the three mechanisms the kidneys can used to respond to a respiratory acidosis?

Answer 3

Increase HCO3- absorption and production

Increase H+ secretion

Question 3

What does high bicarbonate + high pH indicate?

Answer 3

Metabolic alkalosis

Question 5

How is HCO3- absorbed in the proximal tubule?

Answer 5

H+ is secreted into the lumen

Get CO2 and H2O forming in the lumen

They diffuse into the proximal tubule cells

Then dissociate into HCO3- and H+ inside the cell

HCO3- is then pumped out the baso-lateral membrane through a specialised channel

Question 6

Which organ regulates [HCO3-]?

Answer 6

Kidneys

Question 7

Why does metabolic acidosis cause hyperkalaemia?

Answer 7

Short term: High H+ > H+ moves into cells > K+ moves out

Longer term: H+ is preferentially excreted instead of K in the kidney

Question 9

What is the name of the equation used to calculate the bodies pH?

Answer 9

Henderson-Hasselbalch

Question 10

What are two rapidly responding buffering mechanisms?

Answer 10

HCO3-

Hb (takes up H+ ions)

Question 12

How do changes in GIT secretions effect pH?

Answer 12

Acid and HCO3- are secreted in the stomach and duodenum so changes in their secretion will affect pH

Question 13

Which organ regulates the pCO2?

Answer 13

Lungs

Question 14

T/F Left ventricular failure causes metabolic acidosis

Answer 14

False

Question 15

Where else (apart from the proximal tutbule) is HCO3- sequested in the kidneys?

Answer 15

In the distal tubule, H+ is excreted in the process

Question 17

What are the two variables in the Henderson-Hasselbalch equation?

Answer 17

[HCO3-]

pCO2

Question 18

What can a high anion gap indicate?

Answer 18

Lactic acidosis

Diabetic ketoacidosis

Renal failure

Question 19

What is the anion gap?

Answer 19

The difference in electrochemical charge between Na K cations and Cl and HCO3- usually leaves a gap of negative charge at 12mmol. This negative gap is accounted is mostly for by neg. albumin but also acid anions (eg lactic acid)

Question 20

Would the bicarbonate levels in a respiratory alkalosis be high or low?

Answer 20

Low - because it’s compensating