In the hydrogencarbonate buffer in blood, why is there no conjugate base? Surely this means that the pH cannot be

Question: In the hydrogencarbonate buffer in blood, why is there no conjugate base? Surely this means that the pH cannot be increased?
- Keywords:
  buffer,
  ph
Asked by eigenvector to Arttu, Ceri, James_M, Monica, Philip on 21 Jun 2011.
- James M Monk answered on 21 Jun 2011:
  
  I’m by no means an expert on this, but from my A level chemistry all those years ago I seem to remember that a buffered solution contained a compound that would stabilise the pH of a solution by freeing up or binding hydrogen ions. Clearly it is very important that blood stays at the right pH, so I don’t find it at all surprising that blood contains such buffering compounds.
  
  I’m sorry I don’t know more about this subject – it sounds quite interesting.

Question: In the hydrogencarbonate buffer in blood, why is there no conjugate base? Surely this means that the pH cannot be increased?