How+Form+Follows+Function+in+the+CV+System

=How Form Follows Function in the Cardiovascular System = = =


 * The chamber of the **Left Ventricle** has walls that are three times the thickness of the Right Ventricle. This is important because the oxygenated blood that it receives from the Left Atrium has to be pump through the entire body.
 * There are two separate **Vena Cava** veins. The superior vena cava returns blood to the right atrium from the upper part of the body. The inferior vena cava returns blood to the right atrium from the lower part of the body. It is important that they are separated in this way because it creates the ability to take in more blood at one time. If there was only one vena cava, it would have to be much larger or the heart would have to pump much faster.
 * The **ventricles** both have thicker walls than the atria because they must forcefully pump blood out of the heart, while the atria only have to pump blood along to the ventricles.
 * The heart is in close proximity with the lungs, where gaseous exchange occurs.
 * The heart is a pump and needs sets of **valves** to send the blood in one direction. These are the purposes of the tricuspid valve, bicuspid valve, pulmonary semilunar valve, and aortic semilunar valve. When the ventricles contract, atrioventricular valves (bicuspid and tricuspid) close to prevent blood from flowing back into the atria. When the ventricles relax, semilunar valves (pulmonary and aortic) close to prevent blood from flowing back into the ventricles.
 * The **myocardium** of the heart wall is a working muscle that needs a continuous supply of oxygen and nutrients to function with efficiency. For this reason, cardiac muscle has an extensive network of blood vessels to bring oxygen to the contracting cells and to remove waste products. The right and left coronary arteries supply blood to the walls of the myocardium. After blood passes through the capillaries in the myocardium, it enters a system of coronary veins. Most of the coronary veins drain into the coronary sinus, which opens into the right atrium.
 * Having two sets of **pulmonary veins** and **two pulmonary arteries** coming out of the left and right sides of the heart allow for a more efficient pathway to and from the lungs than if there was only one of each.
 * The **aorta** is the largest artery in the body because it is responsible for transporting oxygenated blood from the left ventricle of the heart to the rest of the body through systemic circulation. In addition, the aorta separates from the aortic arch into the ascending aorta and the descending aorta so that all areas of the body can be supplied with oxygen for cellular work. To help force blood along, the arterial walls of the aorta have a layer of smooth muscle cells which allow the artery to expand and contract as blood loses its initial potential energy from the forceful pump of the left ventricle.
 * The heart chamber can extend in both longitudinal and transverse directions because it is made of stratiated cardiac cells which allow for flexibility as the heart pumps blood in and out. The cardiac muscle function relies primarily on an organized assembly of contractile and other sarcomeric proteins.The cardiac cells can grow in length and width.

Here is a good animation of the flow of blood through the heart. http://www.smm.org/heart/heart/pumping.htm