Emergency Medical Technician (EMT) Practice Test

What are the actions of epinephrine?

1. Constricts blood vessels to improve blood pressure

2. Relaxes smooth muscles to improve breathing

3. Stimulates digestion

4. Causes drowsiness

The correct answer is: Relaxes smooth muscles to improve breathing

The primary actions of epinephrine, also known as adrenaline, include constricting blood vessels to increase blood pressure and relaxing smooth muscles in the airways to facilitate breathing. It acts as a bronchodilator, which is particularly important during anaphylactic shock or severe asthma attacks—conditions where airway constriction is a critical concern. While the relaxation of smooth muscles to improve breathing is a vital effect of epinephrine, the more comprehensive understanding includes its ability to achieve multiple physiological outcomes, such as increasing heart rate and cardiac output, as well as increasing blood glucose levels for energy. Considering the context of the options, it is clear that the primary role of epinephrine in the body does not include stimulating digestion or causing drowsiness. Instead, it serves to support survival in emergency situations by optimizing oxygen intake and ensuring adequate blood flow throughout the body. Thus, the action of relaxing smooth muscles to improve breathing is crucial, but it is one among several significant functions that epinephrine performs.