What happens when vagal receptors in the tracheobronchial tree are stimulated?

When vagal receptors in the tracheobronchial tree are stimulated, it typically results in a rapid slowing of the heart rate, a phenomenon known as reflex bradycardia. This occurs due to the activation of the parasympathetic nervous system via the vagus nerve, which transmits signals that can inhibit heart rate. The stimulation of these receptors primarily occurs in response to irritants or mechanical stimulation in the airways. The vagus nerve plays a crucial role in regulating heart function and respiratory responses.

The mechanism involves afferent signals traveling from the stimulated receptors to the central nervous system, which then sends efferent signals through the vagus nerve to the heart, resulting in an increased vagal tone. This increased parasympathetic activity leads to a decrease in the heart rate and can even cause a rapid onset of slowing, which is why the option focusing on a rapid slowing of the heart rate accurately describes the response to vagal receptor stimulation in this context.