In a patient with a plasma pH of 7.1 the HCO3 / H2CO3 ratio in plasma is:
Ans: b (10) Ref: Ganong, 22nd ed, p. 732This is a direct question from Ganong self study MCQs Chapter 39 Q.9This is based on the Henderson-Hasselbach equationpH = pK + log(HCO3)(H2CO3)pK - Ionisation constantIn body fluid it is more appropriate to use the apparent ionization constant ' k' = 6.10 (study by heart)So, pH= 6.10 +log(HCO3-)(H2CO3)pH = 7.1 given7.1 =6.10 +log(HCO3-)(H2C03) log (HCO3-)(H2CO3)= 1log 10 = 1 (HCO3-)(H2CO3)= 10
20
10
2
1
Kidneys and Body Fluids