Final answer:
The bicarbonate buffer system responds to increased alkalinity (metabolic alkalosis) by slowing down the breathing rate, increasing carbon dioxide and carbonic acid levels in the blood to lower pH back to normal. The renal system supports this by modifying bicarbonate reabsorption and hydrogen ion excretion. This adaptability is also crucial for withstanding high altitude conditions.
Step-by-step explanation:
When there is a rise in alkalinity in the bloodstream, indicating a higher than normal pH level, the bicarbonate buffer system engages in a balancing act to restore normal pH levels. The system does this through what is known as respiratory compensation. In cases of increased alkalinity, or metabolic alkalosis, the body's normal response is to lower the breathing rate, which reduces the loss of carbon dioxide (CO2). This leads to increased levels of carbonic acid in the blood, because more CO2 is available to react with water to form carbonic acid (H2CO3), which in turn lowers the pH of the blood back toward normal levels.
The bicarbonate (HCO3-) operates in tandem with carbonic acid. With a usual ratio of 20:1 in favor of bicarbonate in healthy blood pH, the buffer system is more tuned to deal with acids. However, in the face of alkalosis, the renal system may not reabsorb bicarbonate as readily, thereby helping to reduce the alkalinity. Additionally, more hydrogen ions may be excreted, and this process, though slower than respiratory compensation, contributes to the acid-base equilibrium in the long run.
This buffering capability of the bicarbonate buffer system is not just crucial for metabolic stability but also allows adaptation to environmental challenges such as living at high altitudes, where the partial pressure of oxygen and carbon dioxide varies significantly from sea level. Here, the bicarbonate buffer system helps adjust to changes in blood gases without compromising the body's pH balance.