MICROANATOMY

Detailed explanation-1: -The sinus node continuously generates electrical impulses, thereby setting the normal rhythm and rate in a healthy heart. Hence, the SA node is referred to as the natural pacemaker of the heart.

Detailed explanation-2: -The SA node is considered the pacemaker of the heart. Its electrical signals normally cause the atria of an adult’s heart to contract at a rate of about 60 to 100 times a minute. Disturbance anywhere along this electrical pathway can cause irregular heartbeats (arrhythmia).

Detailed explanation-3: -If the sinoatrial node fails, in a normal heart, the atrioventricular node (AV node) should take over the pacemaker function. But the spontaneous rate of the atrioventricular node is lower than that of the sinoatrial node. Hence the heart rate will be lower.

Detailed explanation-4: -The sinoatrial node sends out an electrical impulse that stimulates contraction of the myocardium (heart muscle tissue) This impulse directly causes the atria to contract and stimulates another node at the junction between the atrium and ventricle.