Acid bace balance: tubular mechanisms

Question 1

Gain of H+ in body

Answer 1

• From CO2 in tissue (respiration)
• Metabolism of protein and other organic molecules
• Loss of HCO3- in diarrhoea
• Loss of HCO3- in urine

Question 2

Loss of H+ in body

Answer 2

CO2 excreted through lungs

Utilisation of H+ in metabolism of organic anions

Loss of H+ in vomit

Loss of H+ in urine

Question 3

What are buffers

Answer 3

Represented by ‘B’

They are intra and extracellular cellular phosphates and proteins including Hb. They combine/dissociate with H+

Question 4

What do buffers do in Acidosis

Answer 4

They combine with H+ ions so there are less free H+ ions that make the area acidic

Question 5

What do buffers do in alkalosis

Answer 5

They dissociate from H+ to increase the concentration of free H+ to make the area more acidic

Question 6

What would happen to ventilation in alkalosis

Answer 6

Ventilation to decrease

Question 7

What would happen to ventilation in acidosis

Answer 7

Ventilation would increase

Question 8

How is there renal regulation of pH

Answer 8

H+ and HCO3- regulation because it can determine how much is lost in the urine and also can synthesise bicarbonate

Question 9

How do the kidneys deal with alkalaemia (Low plasma H+)

Answer 9

Inhibit H+ secretion (decrease HCO3- reabsorption) so excreting HCO3- in urine leads to increase in plasma H+

Question 10

HOw do the kidneys deal with acidaemia (high plasma H+)

Answer 10

Kidneys compensate by Increase H+ secretion (excreted in urine) and adding new bicarbonate to blood which decreases plasma H+

Question 11

When does ammonia genesis occur

Answer 11

When there is an increase in plasma H+ conc

Question 12

What does a high level of ammonium in urine indicate

Answer 12

That they have a long standing acidosis