Question

Heart rate of man is mainly controlled by

• A. SA node
• B. Ventricles
• C. Purkinje fibers
• D. AV node

Answer 1

The correct option is A SA node

The cardiac cycle is regulated by specialized areas in the heart wall, that forms the conduction system of the heart. Two of these areas are tissue mass, called as nodes; the third is a group of fibers called as the atrioventricular bundle.

The sinoatrial node, which is located in the upper wall of the right atrium and initiates the heartbeat, is called as the pacemaker.

The second node, located in the interatrial septum at the bottom of the right atrium, is called as the atrioventricular node.

The atrioventricular bundle, also known as the bundle of His, is located at the top of the interventricular septum. It has branches, that extend to all parts of the ventricle walls. Our heart normally beats 70-75 times in a minute (average 72 beats/min).