What role does the heart play in the circulation of blood around the body?

The heart is essential and plays a vital role in the distribution of blood around the body. The circulation system is comprised of two organs: heart and lung. The heart has vessels bringing blood into it from the rest of the body; these are called veins (specifically the inferior vena cava and the superior vena cava). It also has vessels carrying blood away from the heart; these are called arteries (specifically the aorta). The heart is made up of two sets of chambers; atria and ventricles. Atria are the smaller chambers that collect blood first while ventricles are the bigger chambers that are responsible for the pumping of blood out of the heart.The inferior and superior vena cava bring blood into heart. This is de-oxygenated blood as all O2 used up by body. This enters the right atrium first. After entering the right atrium, blood enters the right ventricle when the atria contract. They pass a valve (imagine it as a gate; only lets things past when open and blocks when closed). This is called the tricuspid valve ( tri as it has 3 leaflets and tRi for Right). It then enters the right ventricle and then the pulmonary artery when the ventricle contracts. This goes to lungs to allow the de-oxygenated blood to pick up O2 and become oxygenated . Blood returns to the heart from the lungs via the pulmonary veins into the left atrium. They pass into the left ventricle when the left atrium contracts, passing the bicuspid valve (explain how it is aka mitral and bi as it has 2 leaflets). The left ventricle is much thicker than the right as it needs to generate enough pressure to send blood around the body. This blood enters the aorta when the left ventricle contracts and then is carried around the rest of the body. This blood returns to the heart once it goes around body.