A buffer mechanism is a system that helps maintain a stable environment by resisting changes in pH levels when acids or bases are added. It typically consists of a weak acid and its conjugate base, or a weak base and its conjugate acid. This balance allows the buffer to neutralize small amounts of added acids or bases, keeping the solution relatively constant. In biological systems, buffer mechanisms are crucial for processes like cellular respiration and metabolism. For example, the bicarbonate buffer system in the human body helps regulate blood pH, ensuring that it remains within a narrow range necessary for proper physiological function.