AAOS Emergency Care and Transport of the Sick and Injured Practice Exam 2026 - Free Practice Questions and Study Guide

The tiny sacs of lung tissue specialized for the movement of gases between air and blood are known as alveoli. These structures play a critical role in the respiratory system, forming the interface where the exchange of oxygen and carbon dioxide occurs. The walls of the alveoli are extremely thin and are surrounded by a network of capillaries, allowing for efficient diffusion of gases.

In the context of the respiratory process, as air enters the lungs, it travels through the bronchi and into smaller branches until reaching the alveoli, where the actual exchange takes place. Oxygen inhaled from the air moves across the alveolar wall into the blood, while carbon dioxide from the blood moves into the alveoli to be exhaled. This gas exchange is vital for maintaining proper oxygen levels in the blood and removing carbon dioxide, which is a waste product of metabolism.