Which is an effect of catecholamines?

• A. Decrease heart rate
• B. Increase HR, BP, blood glucose, general stimulation of sympathetic nervous system
• C. Slow respiration
• D. Lower blood glucose

Answer: (B)

Catecholamines unleash the fight-or-flight response, producing a coordinated boost to the body's energy and readiness. They act on adrenergic receptors throughout the body to elevate heart rate and contractility (beta-1 effect), increase vascular tone to raise blood pressure (alpha-1 effect), and stimulate glycogenolysis to raise blood glucose, ensuring tissues have quick energy. They also promote bronchodilation to improve airflow and can increase overall sympathetic arousal. In this context, the hallmark effect is a rise in heart rate, blood pressure, and blood glucose along with general sympathetic stimulation, which is why this choice is the best match. Decreasing heart rate, slowing respiration, or lowering blood glucose would run counter to the body's adrenergic response.