The parasympathetic branch can slow the heart by as much as how many beats per minute?

The correct answer highlights that the parasympathetic branch of the autonomic nervous system can indeed slow the heart rate by about 20-30 beats per minute. This branch, primarily activated through the vagus nerve, has a crucial role in promoting relaxation and recovery after periods of stress or activity. When the parasympathetic system is stimulated, it releases acetylcholine, which acts on the pacemaker cells of the heart, leading to a decrease in heart rate. This modulation is essential for maintaining homeostasis and allows the body to conserve energy, improve digestion, and lower stress-related cardiovascular strain.

The choice indicating 20-30 beats per minute accurately reflects the physiological impact observed in various studies and clinical settings, making it a reliable figure from a biological and health perspective. Understanding this mechanism is fundamental in biofeedback as it helps practitioners utilize techniques that enhance parasympathetic activity to promote relaxation and reduce stress.