For your heart to keep pumping regularly, it needs electrical signals which are sent to the heart muscle telling it when to contract and relax. The electrical signal starts in the right atrium where your heart's natural pacemaker (the sino–atrial node) is. This signal crosses the atria, making them contract.
Answers & Comments
Answer:
For your heart to keep pumping regularly, it needs electrical signals which are sent to the heart muscle telling it when to contract and relax. The electrical signal starts in the right atrium where your heart's natural pacemaker (the sino–atrial node) is. This signal crosses the atria, making them contract.
Explanation: