[tom (OP)]

A rather technical question:
Why is bicarbonate buffer so effective in blood, although the pH of blood (7,4) is far from optimal pH of this buffer, that's 6,1 (the pKa of buffer). I know that body is an opened system, I know the function of  lungs and kidneys, but I haven't yet get satisfactory answer to this problem in literature or web.

[Ylide]

6.1 is the pH of a buffer of equal concentration of bicarbonate and carbonic acid.  In your blood, the concentration of bicarbonate is much higher than the concentration of carbonic acid.  (your blood is warm, gas solubility is rather low in it...carbonic acid is just water + carbon dioxide)  So, it's an unbalanced buffer.  Luckily, your body is capable of regenerating the buffer as needed due to the creation of carbon dioxide in cellular respiration.

I won't bore you with the math, but considering that bicarbonate ion is basic and has a higher concentration than the carbonic acid, it makes sense that the pH of your blood is above the optimal pH of this buffer.  



This message brought to you by The Council of People Who Are Sick of Seeing More People