Thus, each side of the heart forms its own separate system, a right heart and a left heart.Each half consists of an atrium and a ventricle, and blood can flow from the top chamber to the bottom chamber, or ventricle, but not between the two sides.
Thus, each side of the heart forms its own separate system, a right heart and a left heart.Each half consists of an atrium and a ventricle, and blood can flow from the top chamber to the bottom chamber, or ventricle, but not between the two sides.The capillaries have extremely thin walls so that the blood that they carry can come into close contact with the body tissues.
The Circulation of Blood * picture of the heart and its parts * picture of the body and some of its organs The center of the circulatory system is the heart, which is the main pumping mechanism. The heart is shaped something like a cone, with a pointed bottom and a round top. An adults heart is about the size of a large orange and weighs a little less than a pound. The heart is tipped somewhat so that there is a little more of it on the left side than on the right.
It is held in place by the blood vessels that carry the blood to and from its chambers.
So there are actually four chambers (spaces) inside the heart.
Each top chamber is called an atrium (plural: atria). The atria are often referred to as holding chambers, while the ventricles are called pumping chambers.
All of the blood from the body is eventually collected into the two largest veins: the superior vena cava, which receives blood from the upper body, and the inferior vena cava, which receives blood from the lower body region.
Both venae cavae empty the blood into the right atrium of the heart.There are also valves at the bottom of the large arteries that carry blood away from the heart: the aorta and the pulmonary artery.These valves keep the blood from flowing backward into the heart once it has been pumped out.As the blood flows through the capillaries, it also collects carbon dioxide waste from the body cells.The capillaries containing carbon dioxide return this used blood to the heart through a different series of branching tubes: The capillaries join together to form small veins.Lets look at what happens during each cycle: The systemic loop begins when the oxygen-rich blood coming from the lungs enters the upper left chamber of the heart, the left atrium.As the chamber fills, it presses open the mitral valve and the blood flows down into the left ventricle.The veins, in turn, unite with each other to form larger veins until the blood from the body is finally collected into the large veins that empty into the heart.So the blood vessels of the body carry blood in a circle: moving away from the heart in arteries, traveling to various parts of the body in capillaries, and going back to the heart in veins. The human circulatory system is really a two-part system whose purpose is to bring oxygen-bearing blood to all the tissues of the body.In the pulmonary loop, the blood circulates to and from the lungs, to release the carbon dioxide and pick up new oxygen.The systemic cycle is controlled by the left side of the heart, the pulmonary cycle by the right side of the heart.