The heart on it's own is only a useless pump, it is with the help of the vessels which make up the circulatory system that the heart becomes the life sustaining organ that it is. But before we look into all of the details that of the circulatory system, it is helpful to understand its basic design and function. In a nutshell, the circulatory system has a pump (the heart) that sends blood throughout the body by way of many tubes (blood vessels).
This circulating blood pumped by the heart allows for cells and molecules to move from place to place throughout the body. Red blood cells move through the body through the system vessels. Wild blood cells also travel through the circulatory sytem. White blood cells, however, can move through the vessel wall by amoeboid movement. The white blood cells project extensions ahead of them and then follow the path of the extensions. While some cells can move in and out of bloodstream by amoeboid movement, molecules use diffusion as their method of movement.
You may be asking yourself, “Gee, what is blood’s role in all of this transportation mayhem?” Well, it’s actually quite simple. Without the blood to carry the cells and molecules, many processes necessary for survival would not occur quickly enough. Without blood, it would take years for nutrients to diffuse from our stomach to our brain or for gases to travel from our lungs to our leg muscles. This is what makes the cardiovascular system so vital in the life cycle of living things. To learn exactly how the circulatory works read on.