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: -Sinus rhythm is the name given to the normal rhythm of the heart where electrical stimuli are initiated in the SA node, and are then conducted through the AV node and bundle of His, bundle branches and Purkinje fibres.

Detailed explanation-3: -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-4: -Final answer: The rhythmic contraction and relaxation of the heart muscles is initiated by a tissue called Sinoatrial node.

Detailed explanation-5: -The cells of the SA node at the top of the heart are known as the pacemaker of the heart because the rate at which these cells send out electrical signals determines the rate at which the entire heart beats (heart rate).