What prevents the blood from flowing in the wrong direction through the heart?

Heart move blood by pumping action mechanism so also called pumping organ of body. Wall of heart is histologically form of cardiac muscles fibers, while internally the heart is formed of a number of chambers interconnected to one another. Human heart which is also called myogenic heart in whcih the cardiac impulse originates in the cardiac muscle fibers and is not broght to the heart by the nerve fiber. In heart a node known as SA node originate the effectve impulse and these impulse travel throughout the heart through bundle of hiss i.e. the network of impulse carring fibers which allow heart to contract and expand in rhythymic manner so the heart cause pulpating sound and also allow the blood to enter and leave out.