What are some cardiovascular effects of the sympathetic nervous system?

• A. Increased heart rate and blood pressure.
• B. Decreased heart rate and blood pressure.
• C. Rest-and-digest, including decreased heart rate and increased gastrointestinal motility.
• D. No change in heart rate.

Answer: (A)

Sympathetic activation prepares the body for rapid action by boosting cardiovascular output. Norepinephrine release on the heart binds beta-1 receptors in the SA node and myocardium, increasing the heart’s rate, speeding conduction, and enhancing contractility. This raises heart rate and the force of contraction, elevating cardiac output. At the same time, sympathetic fibers often cause vasoconstriction via alpha-1 receptors in many vessels, increasing systemic vascular resistance and arterial pressure. While some regional dilation can occur in skeletal muscle beds, the overall effect during sympathetic activation is a rise in both heart rate and blood pressure. That combination best matches the described cardiovascular effects. The other statements reflect parasympathetic actions (rest-and-digest, decreased heart rate) or no change, which do not fit sympathetic activation.