Question

Choose the correct statement about the sino-atrial node.

• A. Regulates the inflow of blood into aorta
• B. Beating of these fibres result in heart sounds
• C. They are the neurons originating from the brain and ending at the ventricles
• D. Generates action potential without an external stimulus

Answer 1

The correct option is D Generates action potential without an external stimulus

The heart's natural pacemaker or the sino-atrial node (SAN) is a mass of specialised cardiac musculature which is called the nodal tissue. These cells have the ability to spontaneously generate an action potential without any external stimulus. This impulse is radiated across the heart wall with the help of the atrio-ventricular node (AVN), bundle of His and purkinje fibres.