Blood pH

Acidosis occurs when the blood pH is too low.
Alkalosis occurs when it is too high.
During acidosis, chloride ions, which normally help to control osmotic pressure, do not accompany sodium ions back into the bloodstream after they are filtered out in the kidneys. This occurs because bicarbonate ion reabsorption is stepped up instead, in order to return the blood pH to its normal range
Normal blood pH is between 7.35 and 7.45.

Above 7.45 is alkalosis and below 7.35 is acidosis (physiological acidosis, since 7.35 is technically alkaline).

Blood pH is maintained through the bicarbonate buffer system – a mixture of sodium bicarbonate and carbonic acid in the same solution.

Carbonic acid is a weak acid and so does not dissociate readily.
If a strong acid (HCl, for example) is added to the system, the bicarbonate ions of the salt tie up the H⁺ and form more carbonic acid, lowering the pH of the entire solution only slightly.
The weak base, sodium bicarbonate, does not dissociate readily under alkaline conditions, and so if a strong base is added (NaOH, for example), carbonic acid will be forced to dissociate, donating more H⁺ to tie up the free hydroxyl groups, and increasing alkalinity only slightly.
Sodium bicarbonate can also be replaced with potassium and magnesium salts