North Carolina EMT State Practice Exam

What are alveoli primarily responsible for?

1. Producing mucus for the respiratory tract

2. Exchanging oxygen and carbon dioxide

3. Filtering air entering the lungs

4. Regulating airflow in the bronchial tubes

The correct answer is: Exchanging oxygen and carbon dioxide

Alveoli are the tiny air sacs located at the end of the respiratory bronchioles in the lungs, and they play a pivotal role in the respiratory system. Their primary responsibility is the exchange of gases, specifically oxygen and carbon dioxide, between the air in the alveoli and the blood in the surrounding capillaries. The walls of the alveoli are incredibly thin and are surrounded by a network of capillaries, facilitating this crucial exchange process. When a person inhales, oxygen from the air enters the alveoli, where it diffuses across the alveolar membrane into the blood. Simultaneously, carbon dioxide, which is a waste product of metabolism in the body's cells, diffuses from the blood into the alveoli to be exhaled. This process is vital for maintaining the body’s oxygen levels and removing carbon dioxide, thus playing a crucial role in cellular respiration and overall homeostasis. Understanding this function highlights the importance of alveoli in respiratory physiology and the necessity for healthy alveoli to ensure efficient gas exchange.