ANATOMY

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 (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract. The signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump. The SA node is considered the pacemaker of the heart.

Detailed explanation-3: -Sino-atrial node is also called of the heart. Q. Assertion :Sino-atrial node (SAN) is called the pacemaker. Reason: SAN generates the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractions of the heart.

Detailed explanation-4: -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).

Detailed explanation-5: -Both nodes are capable of producing their own impulses. Though under normal conditions, when both are functional, SAN leads and AVN follows. That is, SAN activity determines the rate of heart beat. Hence it can be referred to as pace setter for the heart.