Definition of a Buffer
A buffer is a solution containing substances which have the ability to minimise changes in pH when an acid or base is added to it 1.
A buffer typically consists of a solution which contains a weak acid HA mixed with the salt of that acid & a strong base eg NaA. The principle is that the salt provides a reservoir of A- to replenish [A-] when A- is removed by reaction with H+.
Buffers in the Body
The body has a very large buffer capacity.
This can be illustrated by considering an old experiment (see below) where dilute hydrochloric acid was infused into a dog.
