Florida State Paramedic Practice Exam

Which physiological process occurs primarily in the alveoli of the lungs?

1. Absorption

2. Filtration

3. Gas exchange

4. Osmosis

The correct answer is: Gas exchange

The correct answer is gas exchange. This physiological process primarily takes place in the alveoli of the lungs, where oxygen from the air inhaled into the lungs diffuses across the thin walls of the alveoli into the surrounding capillaries. At the same time, carbon dioxide from the blood in the capillaries diffuses into the alveoli to be exhaled. The structure of the alveoli, which features a large surface area and a moist lining, facilitates this efficient exchange of gases. The thin alveolar walls and the close proximity of the capillaries reduce the distance that gases must travel, allowing for rapid diffusion. Understanding gas exchange is crucial for recognizing how the respiratory system maintains oxygen levels in the blood and removes carbon dioxide, which is vital for homeostasis and overall health.