Paramedic National Registry Practice

What is the primary action of adrenergic drugs in the body?

1. Decrease heart rate

2. Increase preload

3. Increase afterload

4. Inhibit blood vessel constriction

The correct answer is: Increase afterload

The primary action of adrenergic drugs, often known as sympathomimetics, is to stimulate the sympathetic nervous system, leading to various cardiovascular effects. Specifically, these drugs often increase vascular resistance, which in turn raises afterload, the pressure against which the heart must work to eject blood during systole. Adrenergic drugs primarily act on adrenergic receptors, which can be found in various tissues throughout the body, including the heart and blood vessels. When these drugs stimulate alpha-adrenergic receptors, one of the outcomes can be vasoconstriction, which directly raises afterload. An increase in afterload can be beneficial in situations where greater perfusion pressure is required, such as in shock states. While adrenergic drugs can have multiple effects, including increasing heart rate and enhancing cardiac contractility, their action of increasing afterload through vasoconstriction is a notable characteristic that directly influences systemic vascular resistance and has significant implications in emergency medicine and treatment protocols.