Which of the following best describes the process of gas exchange in the alveoli?

The correct description of the gas exchange process in the alveoli is that oxygen diffuses into the blood while carbon dioxide diffuses into the alveoli. This occurs due to differences in partial pressures of these gases in the blood and the alveolar air.

In the alveoli, which are tiny air sacs in the lungs, oxygen from the inhaled air has a higher concentration compared to the oxygen concentration in the deoxygenated blood arriving from the body. This concentration gradient facilitates the diffusion of oxygen into the blood. Conversely, carbon dioxide, which is a waste product of metabolism and present in higher concentrations in the blood compared to the alveoli, diffuses from the blood into the alveoli. This process of diffusion is essential for maintaining proper gas levels in the body and supports cellular respiration.

This dynamic ensures that the body receives the oxygen it needs for energy production while effectively eliminating carbon dioxide, a vital aspect of respiratory physiology.