Movement of Blood Through the Heart
The human heart has four chambers: right atrium, right ventricle, left atrium, and left ventricle. Along with four valves: tricuspid, aortic, pulmonary, and mitral. The movement of blood through the heart is a complex process that begins with the right atrium. Deoxygenated blood flows through the superior and inferior vena cava and enters the right atrium. The right atrium then pumps the blood into the right ventricle using the tricuspid valve. When the right ventricle is full, the deoxygenated blood pumps through the pulmonary semi-lunar valve into the pulmonary artery. The deoxygenated blood is then sent to the lungs. Once the blood exits the lungs it comes back to the heart by the pulmonary veins as oxygenated blood. The blood goes into the left atrium and gets pumped through the bicuspid valve into the left ventricle. When the left ventricle fills up with oxygenated blood it pumps through the aortic semi-lunar valve throughout the entire body!
The Heartbeat
The heartbeat is regulated by two different types of cells: conducting cells and contractile cells. When a person is at rest their heartbeat is at an average of 60-100 beats per minute. Yet, if you fall under the average it is nothing to worry about. Everyone's bodies are different! The heartbeat begins at the SA node, located at the base of the heart in the right atrium. This is also known as the pacemaker. Next, the action potential moves across the atria to the AV node. The signal moves down the AV bundle, which then moves to the Purkinje causing the ventricular contraction. The "bump-bump" you hear when your heart beats is actually the valves opening and closing, not the ventricular contraction!