What is the reaction time for the lungs in response to changes in pH?

The correct answer is based on the understanding of how the body regulates acid-base balance through respiratory function. The lungs respond to changes in pH within a timeframe of minutes because they play a crucial role in regulating carbon dioxide levels, which directly affect the pH of the blood.

When there is an increase in carbon dioxide (hypercapnia), which lowers the pH (making it more acidic), the respiratory center in the brain detects this change and increases the rate and depth of breathing. This response helps to expel more carbon dioxide, thus raising the pH back toward normal levels.

This response is relatively quick compared to other regulatory mechanisms in the body. For example, the kidneys regulate acid-base balance over a longer duration, typically hours to days, as they adjust bicarbonate reabsorption and hydrogen ion secretion. Therefore, the minutes it takes for the lungs to respond to pH changes highlights their important and rapid role in maintaining homeostasis.