North Carolina EMT State Practice Exam

What occurs at the alveoli during respiration?

1. Inhalation of carbon dioxide

2. Exchange of gases between air and blood

3. Absorption of nutrients

4. Production of surfactant

The correct answer is: Exchange of gases between air and blood

During respiration, the primary function of the alveoli is the exchange of gases between the air and the blood. The alveoli are tiny air sacs located in the lungs, and they are surrounded by a network of capillaries. When air is inhaled, oxygen enters the alveoli and diffuses across the alveolar membrane into the bloodstream. Simultaneously, carbon dioxide, which is a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled. This process is crucial for delivering oxygen to the body's tissues and removing carbon dioxide, thus maintaining proper respiratory function and homeostasis in the body. The other options, while related to respiratory physiology, do not accurately describe what occurs specifically at the alveoli. For example, inhalation of carbon dioxide is not a typical event during respiration as the primary goal is to take in oxygen. Absorption of nutrients primarily occurs in the digestive system rather than in the lungs. The production of surfactant is an important function for lung mechanics and reduces surface tension in the alveoli, but it is not part of the gas exchange process. Thus, the correct description of the critical function of the alveoli during respiration is the exchange of gases between air and blood.