THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The vagus nerve represents the main component of the parasympathetic nervous system, which oversees a vast array of crucial bodily functions, including control of mood, immune response, digestion, and heart rate.

Detailed explanation-2: -Parasympathetic control of the heart via the vagus nerve is the primary mechanism that regulates beat-to-beat control of heart rate. Additionally, the vagus nerve exerts significant effects at the AV node, as well as effects on both atrial and ventricular myocardium.

Detailed explanation-3: -The sympathetic side increases alertness, energy, blood pressure, heart rate, and breathing rate. The parasympathetic side, which the vagus nerve is heavily involved in, decreases alertness, blood pressure, and heart rate, and helps with calmness, relaxation, and digestion.

Detailed explanation-4: -Autonomic stimulation of the heart rate acts through G-protein coupled receptors (GPCR). Parasympathetic activation (vagus nerve) exerts an inhibitory action on the heart: it slows conduction from the sinus node, leading to bradycardia, and reduces conduction via the atrioventricular node.