Question

The rhythmic beating of the heart is due to

• A. The action of the muscles in the atria only
• B. The action of the muscles in the atria and ventricles
• C. The action of the muscles in the ventricles only
• D. None of the above

Answer 1

The correct option is B The action of the muscles in the atria and ventricles

The entire heart is made of cardiac muscles. A specialized cardiac musculature called the nodal tissue is also distributed in the heart i.e sino-atrial node (SAN- A patch of this tissue is present in the right upper corner of the right atrium )and atrioventricular node (AVN- mass of this tissue is seen in the lower left corner of the right atrium close to the atrioventricular septum). The nodal musculature has the ability to generate action potentials without any external stimuli, i.e., it is autoexcitable. Hence, the rhythmic beating of the heart is due to the action of muscles in the atria and ventricle.

So, the correct answer is 'The action of muscles on the atria and ventricles '.