Kaplan Nursing Entrance Practice Exam

What function do alveoli serve in the body?

1. They support blood circulation

2. They protect the lungs

3. They allow for gas exchange

4. They filter air

The correct answer is: They allow for gas exchange

Alveoli play a critical role in the respiratory system as the primary site for gas exchange. These tiny, balloon-like structures within the lungs are specifically adapted to facilitate the exchange of oxygen and carbon dioxide between the air and the bloodstream. When you inhale, air containing oxygen enters the alveoli. The walls of the alveoli are extremely thin and are surrounded by capillaries, which are small blood vessels. The oxygen passes through the alveolar walls into the blood in the capillaries, where it binds to hemoglobin in red blood cells. Simultaneously, carbon dioxide, which is a waste product of metabolism, moves from the blood into the alveoli to be exhaled. This process is essential for maintaining the body’s oxygen levels and removing carbon dioxide efficiently, making the alveoli vital for respiratory function. Their large surface area, created by the multitude of alveoli in the lungs, enhances this gas exchange process, allowing for efficient oxygenation of blood. While other structures in the respiratory system serve functions like filtration and protection, it is the alveoli that are specifically designed for the exchange of gases, making them crucial for overall respiratory health.