NACA Animal Control Officers Practice Test

Which part of the respiratory system is responsible for gas exchange?

1. Trachea

2. Diaphragm

3. Lungs

4. Nasal/Sinus Cavity

The correct answer is: Lungs

The lungs are the critical components of the respiratory system responsible for gas exchange. This process occurs specifically in the alveoli, which are tiny air sacs within the lungs. The alveoli are surrounded by a network of capillaries, where oxygen from the inhaled air is absorbed into the bloodstream, and carbon dioxide, a waste product of metabolism, is expelled from the blood into the alveoli to be exhaled. This efficient exchange ensures that the body receives a constant supply of oxygen necessary for cellular functions and helps maintain the acid-base balance by eliminating carbon dioxide. In contrast, the trachea serves as the main airway leading to the lungs and primarily functions to transport air, but it does not participate in gas exchange. The diaphragm is a muscular structure that plays a vital role in breathing by contracting and relaxing to help draw air into the lungs and push it out, but it does not engage directly in gas exchange. The nasal and sinus cavities also contribute to the respiratory system by filtering, warming, and humidifying the air entering the lungs, but like the trachea and diaphragm, they are not sites of gas exchange.