Emergency Medical Technician (EMT) Intermediate Practice Exam

More carbon dioxide diffuses out of the bloodstream when what occurs?

1. Fresh oxygen diffuses into the alveoli

2. Deoxygenated blood is pumped to the lungs

3. Carbon monoxide is inhaled

4. Respiration slows down

The correct answer is: Fresh oxygen diffuses into the alveoli

The correct answer involves the process of gas exchange that occurs in the alveoli of the lungs. When fresh oxygen diffuses into the alveoli, it promotes the removal of carbon dioxide from the blood. This process relies on the principle of diffusion, where gases move from areas of high concentration to areas of low concentration. As fresh oxygen enters the alveoli, it creates a concentration gradient that drives the diffusion of carbon dioxide from the deoxygenated blood in the capillaries surrounding the alveoli into the alveolar space. The removal of carbon dioxide is essential for maintaining respiratory homeostasis and ensuring that the blood has a balanced gas composition. In contrast, the other options do not support the process of carbon dioxide diffusion in the same effective way. For instance, while deoxygenated blood being pumped to the lungs does bring carbon dioxide to the area where it can diffuse out, it’s the presence of fresh oxygen in the alveoli that actively enhances this process. The inhalation of carbon monoxide introduces a different gas that competes with oxygen and could impair oxygen delivery rather than facilitating carbon dioxide removal. Lastly, if respiration slows down, it could hinder the rate of gas exchange, reducing the efficiency of carbon dioxide diffusing out of the bloodstream.