Answer is: They can help prevent a deadly change in blood pH.
A buffer can be defined as a substance that prevents the pH of a solution from changing by either releasing or absorbing H⁺ in a solution.
Buffer is a solution that can resist pH change upon the addition of an acidic or basic components and it is able to neutralize small amounts of added acid or base, pH of the solution is relatively stable.
The normal pH in the mammals arterial blood is between 7.35 and 7.50, so acidosis occurs when arterial pH falls below 7.35. Acidosis is a process causing increased acidity (increased hydrogen ion or proton H⁺ concentration) in the blood and other body tissues.
Alkalosis occurs at a pH over 7.45.