How does the heart work?
Average rating:
The heart has four chambers - two atria and two ventricles. The walls of the heart chambers are made mainly of special heart muscle. Each heartbeat starts with a tiny electrical impulse near the top of the heart which spreads through the heart muscle, and makes it contract (squeeze).
The electrical impulse travels first through the walls of the atria, which contract to pump blood into the ventricles. The impulse then travels through to walls of the ventricles, which contract to pump blood into the arteries.
Average rating:
