Kaplan Nursing Entrance Practice Exam

What aspect of the respiratory system do alveoli facilitate?

1. Filtration of air

2. Sound production

3. Gas exchange

4. Inflation of lungs

The correct answer is: Gas exchange

Alveoli are tiny, balloon-like structures within the lungs that play a fundamental role in the respiratory system by facilitating gas exchange. This process is essential for respiratory function because it allows for the transfer of oxygen from the inhaled air into the bloodstream and the removal of carbon dioxide from the blood to be exhaled. Each alveolus is surrounded by a network of capillaries, which are small blood vessels. When air enters the alveoli, oxygen diffuses through the alveolar walls and into the blood in the capillaries, while carbon dioxide moves in the opposite direction, from the blood into the alveoli, to be exhaled. This exchange is driven by concentration gradients – oxygen moves from an area of higher concentration in the alveoli to a lower concentration in the blood, and carbon dioxide moves in the reverse direction. The other options, while related to the respiratory system, do not accurately describe the primary function of alveoli. For instance, the filtration of air occurs primarily in the nasal passages and upper airways, where larger particles are trapped by mucus and cilia. Sound production is facilitated by the vocal cords located in the larynx, not by alveoli. Inflation of the lungs involves the movement of the diaphragm and