What stop the blood from falling back into heart?

The heart is a powerful muscle that pumps blood around the body. It does this by contracting and relaxing its chambers, which are filled with blood. When the heart contracts, it squeezes the blood out of the chambers and into the arteries, which carry it to the rest of the body. When the heart relaxes, the blood flows back into the chambers from the veins, which carry it back to the heart.

There are several mechanisms that help to stop the blood from falling back into the heart when it relaxes. These include:

* The valves of the heart. The heart has four valves that help to control the flow of blood. The mitral valve (or bicuspid valve) and the tricuspid valve are located between the atria and ventricles. The aortic valve and the pulmonary valve are located at the exits of the heart. When the heart contracts, the valves close to prevent the blood from flowing back into the atria or ventricles.

* The pressure of the blood in the arteries. The blood pressure in the arteries is higher than the blood pressure in the veins. This helps to keep the blood flowing in the right direction.

* The elasticity of the arteries. The arteries are elastic and they stretch as the blood flows through them. This helps to maintain a steady flow of blood.

These mechanisms work together to keep the blood flowing in the right direction and to prevent it from falling back into the heart.