Kaplan Nursing Entrance Practice Exam

What are the tiny air sacs in the lungs called?

1. Bronchioles

2. Alveoli

3. Capillaries

4. Trachea

The correct answer is: Alveoli

The tiny air sacs in the lungs are called alveoli. These structures are crucial for the respiratory system because they are the sites where gas exchange occurs. Alveoli have thin walls that allow oxygen and carbon dioxide to pass through easily. When you inhale, oxygen enters the alveoli, where it diffuses into the surrounding capillaries to be transported into the bloodstream. Simultaneously, carbon dioxide, which is a waste product of metabolism, is expelled from the blood into the alveoli to be exhaled. This process is essential for maintaining oxygen levels in the body and removing carbon dioxide effectively. Understanding the role of alveoli is fundamental in learning how the respiratory system functions to support overall health.