The heart drives the circulatory system as it pushes blood through an intricate system of blood vessels including arteries, capillaries, and veins. Blood is essential as it carries oxygenated blood from the lungs to the tissues and transports waste products like carbon dioxide away where it is expelled from the body.
The heart is hollow and its strong musculature allows it to contract to pump blood to the arteries to be delivered to the rest of the body. One of the most fundamental aspects of the circulatory system is that veins deliver deoxygenated blood to the heart and arteries deliver oxygenated blood away from the heart. Within the heart there are four chambers; right atrium and ventricle, left atrium and left ventricle. These chambers are separated by valves. There are four valves that separate the different chambers; the mitral valve, tricuspid valve, aortic valve, and the pulmonary valve. The tricuspid valve separates the right atrium and right ventricle. The mitral valve separates the left atrium and left ventricle. The aortic valve is what separates the left ventricle and the aorta. The pulmonary valve separates the right ventricle and the pulmonary artery. Valves work to allow blood flow through into the following chamber while not allowing blood to flow back through. A reverse in the blood flow is called regurgitation and is a serious medical condition that should be addressed. Each valve has two cusps with the exception of the tricuspid valve as it has three.
The heart works like machine constantly pumping blood that is fed to it. There are two venous systems that dump into the right atrium; the inferior vena cava and the superior vena cava. The inferior vena cava carries deoxygenated blood from the lower body back to the heart and conversely the superior vena cava carries deoxygenated blood back to the heart from the upper body and head. The right atrium contracts and pumps blood through the tricuspid valve into the right ventricle. When the right ventricle is filled the tricuspid valve closes off preventing regurgitation.
The right ventricle then contracts that pushes blood through the pulmonary valve and into the pulmonary artery to be carried to the lungs. once inside the lungs blood flows the tiny capillary vessels in the lungs where there is exchange of carbon dioxide and oxygen. Oxygen from the alveolar air sacs diffuses through the capillaries into the blood while at the same time carbon dioxide passes from the blood into the air sacs. The carbon dioxide is then exhaled as one respirates normally. The blood is now oxygenated and travels back through the pulmonary veins where it dumps into the left atrium.
As the left atrium contracts blood is pushed through the mitral valve into the left ventricle. When the ventricle has reached capacity the mitral valve closes, again blocking regurgitation. The left ventricle then contracts and the blood is pushed through the aortic valve into the aorta and the coronary arteries. The aorta supplies the rest of the body with oxygenated blood. The coronary arteries is actually what supplies the heart with oxygen to keep the tissue alive.
There is a right coronary artery and a left coronary artery. The right coronary artery supplies the right atrium and right ventricle. It branches into the posterior descending artery. The left main coronary artery branches into the circumflex artery and the left anterior descending artery. It supplies oxygenated blood to the left atrium and the left ventricle.