Question: what is the main buffer in the extracellular fluid?
Answer: Bicarbonate buffer is the most important buffer system in blood plasma (generally in the extracellular fluid). This buffer consists of weak acid H2CO3 (pK1 = 6,1) and conjugated base HCO3– (bicarbonate). Bicarbonate concentration is given in mmol/l (average value is 24 mmol/l).