How does the heart work?
The heart is a functional muscle that supplies blood to the body. The blood transports oxygen and sustenance to all of the body parts and also carries waste products to multiple organs, particularly to the lungs and kidneys, for removal.
The heart has two pumps, that work together. The blood that comes back from the organs and tissues of the body gets into the right side of the heart, which then transports it to the lungs. The heart is situated on the left side of the chest, behind the breastbone.
The chambers of the heart
The heart has four parts, called chambers: two atria at the top part and two ventricles at the bottom part. The atria collect the blood, pump it to the ventricles, which further pump it towards the lungs and the body.
The valves of the heart
The direction of the blood flow is coordinated by the valves, which are located at the entrance and exit of each heart ventricle. The four valves are the tricuspid valve, the pulmonic valve, the mitral valve, and the aortic valve.
The circulation of the blood inside the heart
The circulation starts in the right atrium, where the blood coming from the body is collected, goes into the right ventricle through the tricuspid valve, and then goes into the lungs through the pulmonary valve. The oxygen-rich blood flows back to the heart in the left atrium, goes to the left ventricle through the mitral valve and leaves the heart through the aortic valve being pumped towards the rest of the body. The valves help the blood flow in and out of the ventricles and prevent the blood from flowing backward.
The actual pumping of the heart is controlled by the electrical system of the heart through electrical signals generated by the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node is at the top of the right atrium and controls the pace of the heart. The AV node is at the top of the right ventricle. It is in charge of the contraction of the atrium and channels the signal towards the ventricles which contract at the same time, pumping the blood towards the lungs and the body.