The organ system in which the blood is pumped through the heart and circulates throughout the body through the blood vessels. The cardiovascular system is a closed circulatory system seen in humans and other vertebrates. Its components include the heart, blood vessels, and blood. The heart has chambers such as the atrium (pl. atria) and the ventricle(s). In humans, there are four heart chambers, i.e. two atria and two ventricles.
Cardiovascular biology is the study of the mechanisms of cardiovascular physiology and pathophysiology like functions and activities of the cardiovascular system as a whole or of any of its parts.