Best buffer of human blood:

Ans. a (HCO3). (Ref. Guyton physiology 11th ed. 385-387;Ganong, Physiology, 21st/736)# Phosphate buffer system is not important as an extracellular fluid buffer, it plays a major role in buffering renal tubular fluid and intracellular fluids.# The buffer system that is quantitatively the most important in the extracellular fluid--the bicarbonate buffer system.Principal buffers in body fluids1. BloodH2CO3 K H+ +HCO-3 HProt K H+ + Prot- HHb K H+ + Hb-2. Interstitial fluidH2 CO3 KH+ + HCO 33. Intracellular fluidHProt KH + + HCO3, H2PO4 - KH-+ HPO4 2-# For ECF especially blood plasma the predominant buffer is HCO3- (Bicarbonate buffer). Bicarbonate thus acts as major buffers in ICW as well as ECW, but proton s are important buffers only in ICW.