What term describes the amount of air that reaches the alveoli?

The term that specifically describes the amount of air that reaches the alveoli is "alveolar ventilation." Alveolar ventilation is a critical measurement in respiratory physiology that indicates the effectiveness of the respiratory system in facilitating gas exchange. It reflects not only how much air is inhaled but also how much of that air actually participates in oxygen and carbon dioxide exchange at the alveolar level.

In this context, it's important to understand the broader concept of ventilation, which refers to the overall movement of air in and out of the lungs. However, not all of the air that enters the lungs actually reaches the alveoli due to anatomical dead space where no gas exchange occurs. Alveolar ventilation provides a more precise understanding by focusing exclusively on the air that effectively participates in the exchange of gases, making it a vital factor in assessing respiratory function and health.

Cellular respiration pertains to the metabolic processes within cells where oxygen is consumed and carbon dioxide is produced, which occurs after alveolar ventilation. Diffusion relates to the movement of gases across membranes, particularly in the context of oxygen and carbon dioxide moving between the alveoli and the bloodstream, but it does not measure the volume of air reaching the alveoli directly.