SA node versus AV node

Answer 1

1) Sino-atrial node is master node and atrio-ventricular node is on the path from SA node to impulse to ventricles.

2) SA node has intrinsic rhythme rate of about 72 beats/ minute and AV has intrinsic rhythme rate of about 50 beats per minute.

3) SA node has autonomic ( sympathetic and parasympathetic ) nerve supply and AV node do not have any such supply.

4) SA node regulates the heart rate and AV node slows down the conduction across the path, so that atria gets time to contract, to be fallowed by contraction of ventricles.

5) Disease of the SA node generally leads to sick sinus syndrome. Disease of the AV node generally leads to atrioventricular block.

Answer 2

Cardiac muscles has intrinsic rhythmicity. That mean the muscle fibre contract rhythmically. The different types of cardiac muscle fibres contract at at different rhythm. SA node contract at the rate of 72 beats / minute. The other atrial muscle fibres contract at the rate of 60 beats / minute. The AV node contracts at the rate of 50 beats /minute. The ventricle muscle fibres contract at the rate of 36 beats / minute. The fibres from the bundle of His contract in between 50 to 36 beats / minute. So the SA nodes contract at the fastest rate and it is a 'Pace maker'. That means SA node decides the rate of contraction of your heart. It is supplied by sympathetic as well as parasympathetic innervation to rise or lower the heart rate. In AV node you have the conduction of the impulse slowed down for a movement. So that the ventricles should contract 'after' the contraction of the atria. This helps you to have proper pumping of the blood in forward direction.

Answer 3

The sinoatrial (SA) node is the heart's natural pacemaker, generating electrical impulses to initiate each heartbeat. The atrioventricular (AV) node receives these impulses from the SA node and helps to delay them slightly before transmitting them to the ventricles, allowing for coordinated contraction of the atria and ventricles.