Lecture 31: Acid-base balance

Question 1

What is the Henderson Hasselbach Equation?

Answer 1

pH = pKa + log (A/HA)
pH = 6.1 + log ([HCO3-]/0.03*PaCO2)

Question 2

What are the 3 ways to compensate for acid-base disturbance?

Answer 2

Intra/extracellular chemical buffering (very fast, limited capacity)
Change in ventilation (slower, less limited)
Change in kidney secretion (very slow, limitless)

Question 3

Describe the processes of respiratory acidosis and alkalosis

Answer 3

ACIDOSIS: PaCO2 is higher b/c of limited gas exchange, so pH decreases. HCO3- is slightly higher. Renal compensation causes H+ secretion, so pH increases, HCO3- increases. Jump to different isopleth, then move

ALKALOSIS: PaCO2 is lower because of hyperventilation, so pH increases. This causes lower HCO3-. Renal compensation is less H+ excretion, so this causes lower HCO3-.

Question 4

Describe the processes of metabolic acidosis and alkalosis

Answer 4

ACIDOSIS: drop in pH due to low HCO3- (diarrhea). respiratory compensation is going to cause hyperventilation, drop in PaCO2. less CO2 will further decrease HCO3-, will increase pH.

ALKALOSIS: increase in pH due to loss of H+ ions (vomiting), respiratory compensation is to induce shallow breathing, this will increase PaCO2. more CO2 = more HCO3-, but also decrease in pH.