Ace the Cardiac Vascular Nursing Exam 2025 – Pump Up Your Success!

The parasympathetic nervous system primarily acts to decrease heart rate. It exerts its influence through the release of acetylcholine from the vagus nerve, which binds to receptors in the heart, particularly in the sinoatrial (SA) node. This interaction leads to a reduction in heart rate by causing hyperpolarization of the heart cells, making it less likely for them to reach the threshold needed for depolarization and subsequent contraction.

In a normal resting state, the parasympathetic nervous system plays a crucial role in maintaining a lower heart rate, which is vital for energy conservation during periods of rest and relaxation. This contrasts with the sympathetic nervous system, which increases heart rate during stress or physical activity.

Other choices may suggest either an increase in heart rate, no effect, or stabilization, which do not accurately reflect the role of the parasympathetic nervous system in cardiac physiology. By focusing on the primary function of decreasing heart rate, the chosen answer correctly captures the essential regulatory mechanism of the parasympathetic nervous system in cardiac function.