The circulatory system includes the heart and blood vessels. The system’s main function is to provide oxygen and nutrients to tissues and organs throughout the body and removes wastes from cells and organs.

Vena cava – the largest vein in the body that transports blood from different body parts back to the heart. It has two parts the superior vena cava which carries blood from the head, neck, chest, and arms, and the inferior vena cava which carries blood from the legs, feet, and abdominopelvic region.

Vein – in the systemic circulation, it carries deoxygenated blood from different body parts back to the heart; in the pulmonary circulation, the pulmonary vein carries oxygenated blood from the lungs back to the heart.

Artery – in the systemic circulation, it carries oxygenated blood from the heart to the various parts of the body; in the pulmonary circulation, it carries deoxygenated blood from the heart to the lungs.

Spleen – a small organ in the left hypochondriac region that stores blood and filters blood by removing waste and old or damaged blood cells. It is known as the graveyard of red blood cells.