Ok so buffers are really just an equilibrium system held in the body to maintain pH levels.
One of the most important buffers in the human body is the hydrogen carbonate ion buffer:
CO3(2-) + H2O ⇌ HCO3(-) + H3O(+) ⇌ CO2 + H2O
Effects such as acidosis only become prevalent when the buffer system breaks down. Before then, however
Note that your human body has a relatively even concentration of both the carbonate ion CO3(2-) and the hydrogen carbonate ion HCO3(-). Consider only the first two reactants and products. If the blood in the human body suddenly becomes more acidic, then according to LCP the equilibrium will shift to the left to reduce the amount of pH present. The HCO3(-) ion is then converted to the CO3(2-) ion, which isn't really basic when in low quantities, and effectively allows body pH to be regulated (by removing excess acid, H+).
By extension, the amount of CO2 in our body will also increase. LCP is able to predict that the equilibrium will shift ALL the way to the left
When we breathe out, our body eliminates CO2. To cater for the lost CO2 in the body, the equilibrium will shift to the right, and thus the excess CO3(2-) produced will then be eliminated.
[If the pH of the blood becomes alkaline, then this also shifts the equilibrium to the right to minimise such disturbances.]
Buffers are referred to as that because there exists roughly an equal concentration of HCO3(-) AND CO3(2-) in the system. Because both substances are present, it is quite obvious that dynamic equilibrium will eventually be achieved, but note that minute changes to the body's pH do not stir up the equilibrium greatly. It will take quite a significant amount of acid to start affecting a buffer system.
In essence, the buffer's role is to MINIMISE disturbances to the body naturally. There is a point where it breaks down, but the whole point of buffers is that it won't anytime soon.
