Question

Impulse of heart beat originates from
A.SA node
B.AV node
C.Vagus nerve
D.Cardiac nerve

Answer 1

The heartbeat is caused by electrical impulses that move through our heart along a special pathway. The atria and ventricles function together, contracting and relaxing alternately to pump blood through the heart.

Complete answer:
Let us analyze the options to find out the correct option.

Option A: In a small bundle of specialized cells situated in the right atrium, called the SA node, the impulse of heart beat begins. The electrical activity spreads and induces them to contract across the walls of the atrium. In the ventricles, the blood is pushed by this. The SA node sets the heartbeat's rate and rhythm. Since the SA (sinus) node periodically flares, natural heart rhythm is also referred to as normal sinus rhythm. Therefore, this is the correct option.

Option B: AV node (atrioventricular node) is a cluster of cells between the atria and ventricles in the center of the heart and acts like a gate that is responsible for slowing down the electrical signal before it reaches the ventricles. This delay allows the atria to contract until the ventricles do. Therefore, this is the incorrect option.

Option C: Vagus nerve is the 10th cranial nerve and is involved in the parasympathetic control of organs like heart, lungs and digestive tract. Therefore, this is the incorrect option.

Option D: Cardiac nerves are a network of autonomic nerves which supply to the heart. Therefore, this is the incorrect option.

Hence, the correct answer is option (A)

Note: 1.The SA node produces an electric impulse 60-100 times per minute under normal circumstances.
2.The impulse travels from SA node to AV node.