How our bodies maintain PH balance?

The PH level in our bodies is maintained around 7.4. We breathe in oxygen all the time. Oxygen is highly acidic, (electron attracting). Our bodies need to discharge acids all the time to maintain PH level. There are mainly two channels to discharge acids. We breathe out carbon dioxide, which is acidic. We also discharge acidic urine. Are these two methods equivalent?

When we breathe out too much carbon dioxide (CO2), the level of bicarbonate (HCO3(-)) in our bodies will be low. The corresponding chemical equation is H2O + CO2 <> H(+) + HCO3(-). From the above equation, bicarbonate provides buffer to the increase of hydrogen ion. If the level of bicarbonate is low, the buffer capacity is small. When we exert ourselves, the sudden increase of H(+) cannot be neutralized. H(+) is acidic and tastes sour. We will feel sour and tired.

When our kidneys are weak, we couldn’t discharge enough H(+) through kidneys. We have to rely more on breathing to maintain PH balance. As a result, the bicarbonate level in our bodies is low. We could not provide big buffer necessary for heavy exertion. We feel tired easily. 

There are mainly two ways to maintain PH balance. Physiologically, they are not equivalent.

When one kidney is removed from our body, it weakens our health.