The heart and the circulatory system are the components of the cardiovascular system. The function of the cardiovascular system is to circulate blood through out the body.The healthy heart beats on average of 100,000 times daily. It receives circulated blood through the veins and pumps blood to the lungs for oxygenation. Oxygenated blood is returned to the heart and pumped through arteries to the entire body.
The Heart
The heart contains four chambers. The upper chambers are the left and right atria. The lower chambers are the left and right ventricles. The septum is a muscle which separates the left side from the right side of the heart.
There are four valves that control the flow of blood within the heart. The tricuspid valve controls the blood flow from the right atrium to the right ventricle. Oxygen poor blood is brought from circulation through the superior vena cava into the right atrium. The pulmonary valve regulates blood flow from the right ventricle to the pulmonary arteries and into the lungs where the blood will receive oxygen. The oxygenated blood passes from the lungs through the mitral valve into the left ventricle. The aortic valve controls the blood flow from the left ventricle into the aorta. Oxygen rich blood is carried from the aorta into circulation by the arteries.
The heart muscle, also referred to as the myocardium, has a conductive system. It is the electrical impulses of the cardiac conductive system that cause the heart to contract. It is the contraction that causes the pumping action of the heart and is felt as a pulse. The sinoartrial node (SA node) is located in the upper portion of the right atrium. The electrical impulse from the SA node travels through a network of cells to the AV node. The AV node is located in the center of the heart between the atria and the ventricles. It functions as a check point allowing the atria to contract before the ventricles are stimulated.
The Veins
The veins are the part of the circulatory system that carry blood from the body back to the heart. The walls of the veins are thinner in composition than the walls of the arteries. The largest vein is the vena cava, which has two branches, the superior vena cava and the inferior vena cava. The superior vena cava carries blood from the head and arms to the right atrium of the heart. The inferior vena cava transports blood that has circulated through the lower parts of the body to the right atria. Major veins that drain into the vena cava are the jugular veins, the brachial and cephalic veins, the femoral veins, and the iliac veins. Four pulmonary veins transport oxygenated blood from the lungs to the left atrium.
The Arteries
The arteries are the blood vessels that carry oxygenated blood from the heart to other parts of the body. Like veins, arteries have three layers, but the middle and inner layers are thicker. This difference allows the arteries to be elastic and accommodate the pressure of blood being pumped from the heart. The aorta is the largest artery in the body and divides into two major blood vessels: the right coronary artery and the left coronary artery. The right coronary artery supplies the right side of the heart and delivers blood to the lungs. The left coronary artery supplies the left side of the heart which supplies oxygenated blood to the body. The left coronary artery branches into the left anterior, descending artery and the circumflex artery. Arterioles are smaller blood vessels that branch from the larger arteries. Capillaries are microscopic blood vessels that branch from arterioles. Capillaries join to form venules. Venules that are located close to the heart merge to form veins.
