The
pH of your blood is around 7.5. A
rise in
pH (alkalosis) to just 8.0 can be fatal, as is a drop in
pH to 7.0 (acidosis). How does your blood maintain
pH stability? The secret lies in the
combination of weak acid, H
2CO
3, and a weak base, HCO
3-1, that are naturally dissolved in your bloodstream. H
2CO
3, the same
acid that is present in carbonated beverages, is formed as your blood picks up waste CO
2. (You might remember that carbon dioxide is a byproduct of cell respiration and combustion.) In solution, it disintegrates into a weak base, HCO
3-1, sometimes called bicarbonate ion. Both H
2CO
3 and HCO
3-1 are normally present in blood. In chemistry, such a
combination is called a weak conjugate acid-base pair.
The presence of the weak
acid (H
2CO
3) in blood is important. It absorbs base, and prevents
pH of your blood from becoming too high. The weak
base (HCO
3-1) is equally important since it absorbs excess
acid that might otherwise build up it your blood.