The human heat is a muscle, responsible for pumping blood through out the body. It begins to pump while we are still in our mothers womb and does not stop until we die. At resting, the heart will beat an average 60 beats per minute. However when under stress, this can increase to 200 beats per minute.

Unlike normal muscles the heart is made of cardiac muscle. The reason for this is its work rate. Beating over 35 million times per year or 100,000 per day, if it where made of normal skeletal muscle it would cramp up.

So as stated in the above video:

1. Blood is returned from the body through the superior and inferior vena cava
2. Blood enters the heart in the right atrium
3. Blood the passes from the right atrium to the right ventricle
4. The blood is then pumped through the pulmonary artery to the lungs
5. Blood releases its carbon dioxide and gains oxygen. It becomes re-oxygenated.
6. The blood then leaves the lungs and re-enters the heart through the pulmonary vein
7. The blood in poured into the Left atrium
8. The blood then enters the left ventricle
9. The blood is squeezed out of the ventricle and passed through the Aorta to the body.

Flow of blood in and out of the heart

The heart has two sides to it. One is oxygenated, while the other is de-oxygenated. This is referred to as the double pump system. The beating heart goes through a cycle of contraction and relaxation. Contraction is known as systole while relaxation is known as diastole.

During systole the ventricles contract forcing blood into the body and lungs. The right ventricle contracts a little before the left ventricle.

When blood leaves the heart it goes through the Aorta, this artery is thick as the blood is under high pressure. This is because the blood has to go to the entire body.

During diastole the ventricles relax and are filled with blood coming form the atria.

Click here for a heart dissection