Final answer:
The alveolar ventilation rate is indeed the best index of effective ventilation because it accounts for the volume of air that reaches the gas exchange areas in the lungs per breath, which is crucial for proper oxygen and carbon dioxide exchange.
Step-by-step explanation:
True, the alveolar ventilation rate is the best index of effective ventilation. Alveolar ventilation refers to the flow of air into and out of the alveoli, the tiny air sacs in the lungs where gas exchange occurs. It is more accurate than simply measuring the respiratory rate because it considers the volume of air that reaches these gas exchange sites during each breath. Effective alveolar ventilation ensures that enough oxygen reaches the bloodstream while carbon dioxide is removed efficiently.
When alveolar ventilation is too low, carbon dioxide can accumulate in the blood, leading to respiratory acidosis. In this case, the body typically responds by increasing the respiratory rate to blow off more carbon dioxide. If alveolar ventilation is too high, it can lead to respiratory alkalosis, where too much carbon dioxide is removed, and the respiratory rate may decrease to compensate.
The work of breathing includes the effort required to inflate and deflate the lungs. The respiratory rate (number of breaths per minute) and the tidal volume (the volume of air per breath) can adjust to maintain steady alveolar ventilation according to the body's needs. This can be achieved by varying the respiratory rate and tidal volume inversely. Increased oxygen demand, such as during exercise, requires closely regulated adjustments to both respiratory rate and tidal volume to maintain effective alveolar ventilation.