Question

Origin of heart beat and its conduction is represented by

• A. AV node $\to$ Bundle of His $\to$ SA node $\to$ Purkinje fibres
• B. SA node $\to$ Purkinje fibres $\to$ AV node $\to$ Bundle of His
• C. Purkinje fibres $\to$ AV node $\to$ AV node $\to$ Bundle of His
• D. SA node $\to$ AV node $\to$ Bundle of His $\to$ Purkinje fibres

Answer 1

Answer: (D)

SA node $\to$ AV node $\to$ Bundle of His $\to$ Purkinje fibres

A specialised cardiac musculature, called as the nodal tissue is distributed in the heart. A patch of this tissue is present in the right upper corner of the right atrium, called as the sino-atrial node (SAN). Another mass of this tissue is seen in the lower left corner of the right atrium close to the atrio-ventricular septum, called as the atrio-ventricular node (AVN).

A bundle of nodal fibres, atrioventricular bundle (AV bundle) continues from the AVN, which passes through the atrio-ventricular septa to emerge on the top of the interventricular septum and immediately divides into a right and left bundle.

The rhythms generated in the SAN is transported to the AVN, from where it will go through the bundle of His to the Purkinje fibres at the end. Thus, the heart beat is conducted in the heart.