What will cause the sinoatrial (SA) node to depolarize more frequently? A. Acetylcholine B. Norepinephrine C. Parasympathetic stimulation D. Vagus nerve
Option B. Norepinephrine (Released through the sympathetic nervous system) appearing at the SA node will increase coronary heart rate and blood pressure. Parasympathetic stimulation alongside the vagus nerve decreases coronary heart activity.
