Emergency Medical Technician (EMT) Basic Certification Practice Exam

What occurs during active inhalation?

1. Pressure rises and air is forced out

2. Pressure drops and air is sucked in

3. Ribs are fractured in multiple places

4. Air is trapped in the pleural space

The correct answer is: Pressure drops and air is sucked in

During active inhalation, the diaphragm and intercostal muscles contract, resulting in an increase in the volume of the thoracic cavity. This increase in volume creates a decrease in pressure within the lungs compared to the atmospheric pressure outside the body. Because of this pressure difference, air is drawn into the lungs, which is accurately described as air being "sucked in." The mechanics of breathing fundamentally rely on pressure changes; when the pressure inside the lungs drops, air flows in to equalize the pressure, thereby facilitating effective respiration. The other options do not accurately describe the process of active inhalation. For instance, an increase in pressure within the thoracic cavity would lead to air being forced out rather than inhaled. Fractured ribs are unrelated to the mechanics of respiration and signify a potential injury rather than a normal physiological process. Similarly, trapping of air in the pleural space refers to a pathological condition such as a pneumothorax, which does not occur during the normal process of inhalation.