The cardiovascular system consists of three things. The heart, blood vessels, and the blood. This system is powered by the heart. Nutrients, oxygen, and hormones are transported throughout the body through blood vessels. A healthy heart can beat from 60 to 100 times per minute.
There are two circulatory loops in humans: the pulmonary circulation loop and the systemic circulation loop. The pulmonary circulation loop moves deoxygenated blood from the heart to the lungs, where oxygen is added to the blood and it is returned back to the heart. The systemic circulation carries oxygenated blood from the heart to the tissues of the body, and then takes the deoxygenated blood back to the heart.
Blood vessels allow blood to flow quickly and efficiently from the heart to every region of the body and back again. There are three major types of blood vessels: arteries, capillaries and veins.
Arteries are blood vessels which transport blood away from the heart. Arterioles are the same as arteries except the are smaller and they extend off the end of the arteries. They carry the blood the the capillaries which are the thinnest blood vessels. Veins are the opposite of arteries; the bring the blood back to the heart. Venules are the same as arterioles except the attach to veins.
Blood moves substances throughout the body. It also helps maintain homeostasis of wastes, nutrients, and gases. It consists of red blood cells, white blood cells, platelets, and liquid plasma.