The transports oxygen and nutrients to the body and moves waste products like carbon dioxide and urea away from cells for excretion or breakdown.
The systemic circulation exits the heart with oxygen rich blood and returns with oxygen poor blood.
The heart consists of two sides, the left side and the right side. In diagrams you will be presented with, the sides of the heart, flipped around. This is because you are always presuming to be looking at a heart as if it were in another person.
The left side carries oxygen rich blood from the lungs to the rest of the body.
The right side carries oxygen poor blood from around the body to the lungs.
The heart also has four chambers. A left atrium and left ventricle and a right atrium and right ventricle.
The is the chamber of the heart where blood enters, and the is the chamber of the heart that pumps blood out of the heart.
Blood enters the left side of the heart from the
The pulmonary vein contains oxygen rich blood, carried from the lungs.
The pulmonary vein feeds into the left atrium. The left atrium contains a valve called the This valve remains closed until the left atrium is filled at which point the valve opens and the left atrium pumps blood into the left ventricle.
The left ventricle has a thick muscular wall, far denser than the right ventricle because it pumps blood all the way around the body.
The right ventricle fills with blood and contracts sending blood through the semilunar valve and around the body through the aorta.
Blood then moves through the body and eventually returns to the heart, deoxygenated that is to say without oxygen, via the vena cava.
The deoxygenated blood enters the right atrium. Once full the right atrium contracts to push blood through the tricuspid valve and into the right ventricle, which contracts and pushes blood through the semilunar valve into the pulmonary artery towards the lungs to become oxygenated.
The cycle then begins again.