6.1 Acid-base Balance Flashcards
What is the range of healthy plasma pH?
7.35 to 7.45
What is it called when pH drops below 7.35?
Acidaemia
What is it called when pH rises above 7.45?
Alkalaemia
What symptoms are felt in alkalaemia?
Paraesthesia- Ca2+ release
What symptoms are felt in acidaemia?
Arythmyias- K+ release
Denatured proteins
How is pH determined in the plasma?
Ratio of pCO2 and [HCO3-]
What equation is used to work out pH of the plasma?
Hasselbach’s equation
What is Hasselbach’s equation?
pH= pK + log( [HCO3-] /pCO2 x 0.23)
What is respiratory acidosis?
Hypoventilation leads to a build up of CO2 which lowers the pH of the blood
What is respiratory alkalosis?
Hyperventilation leads to a loss of CO2 and therefore the pH increases
What do central chemoreceptors detect?
Detect changes in pO2
What do peripheral chemoreceptor detect?
Detect changes in pCO2 and plasma pH
How are changes in pCO2 compensated for?
Kidney can reabsorb or excrete HCO3-
Alter breathing
What is metabolic acidosis?
H+ reacts with HCO3- in the tissues to produce CO2
CO2 is removed at the lungs
[HCO3-] is lowered so pH drops
How is metabolic acidosis compensated for?
Increase ventilation
When may metabolic acidosis occur?
Exercise
What is metabolic alkalosis?
Plasma HCO3- rises so pH rises
When may metabolic alkalosis occur?
After vomitting lots
Where is most of HCO3- reabsorption done in the kidney?
PCT
How does HCO3- cross the apical membrane in the PCT?
Joins with H+ to become H20 and CO2. They diffuse into cell. Turns back into HCO3- when inside the cell
How does HCO3- move across the basolateral membrane of the PCT cells?
Via Na-HCO3-co-transporter
Which amino acid can be converted to HCO3-?
Glutamine
What buffers the influx of H+ to the lumen as HCO3- is reabsorbed?
HPO4+
How is the anion gap calculated?
Difference between ([Na+] and [K+]) and ([Cl-] and [HCO3-])
What would a large anion gap suggest?
Metabolic acidosis
What happens to potassium levels in metabolic acidosis?
Increase
What happens to potassium levels in metabolic alkalosis?
Decrease