Question

Sino-atrial nodes are called the pacemaker of our heart. Why?

Answer 1

Within the right atrium, near the opening of the superior vena cava, a small structure, called sinoatrial node (SAN), is situated. Atrioventricular node is present near the tricuspid valve, within the right atrium. SAN can generate maximum number of action potentials and initiates rhythmic contractile activity of the heart, that’s why it is called pacemaker of the heart.

Complete answer:
Sinoatrial (SA) node is present in the right atrial wall. Its main function is to initiate cardiac action potentials, which set basic pace for the heart rate and conduct throughout both atria. Atrioventricular node present in septum between atria. A bundle of nodal fibers, called atrioventricular bundle ( AV bundle), begins from the AVN and after traversing a short distance along the interventricular septum splits into right and left branches. The individual branches then turn to enter the heart muscles where they branch extensively and this branch extensively and this branch system is called fibers of purkinje. SAN, AVN, AV bundle and purkinje fibers all together form a system whose function is to create impulse (pace making) and convey the impulse to every part of the heart.
Since, SAN can generate the maximum number of action potentials about 70-75 per minute, and is responsible for initiating and maintaining the rhythmic contractile activity of the heart, it is called the pacemaker of the heart.
Pacemaker was first used by Chardack in 1960. It is revolutionized for the treatment of heart blocks. A pacemaker is a tiny computerized electrical device that is implanted in a patient's body to regulate heart beat. It consists of two parts: a pulse generator and an electrode. In heart block patients, the pacemaker is introduced with the aim to supply to the heart proper stimuli, so that lack of natural impulse will not result in cardiac standstill.
From the above information it is explained that the Sino atrial node is called the pacemaker of our heart.

Note: Sinus node dysfunction causes various symptoms like fatigue, dizziness, and decrease in exercise. Various types of pacemakers are used but the most popular type is demand ventricular pacemaker. The pacemaker helps the patient to lead essentially normal life. When natural impulses are missed this type of pacemaker detects missing impulses and supplies artificial stimuli.