heart and blood vessel disorders
Biology of the Heart
Blood Supply of the Heart
Like all organs, the heart needs a constant supply of oxygen-rich blood. Even though the heart chambers are full of blood, the heart muscle needs its own dedicated blood supply which is called the Coronary circulation The coronary circulation is the system of arteries and veins that supplies the heart muscle (myocardium) with oxygen-rich blood and then returns oxygen-depleted blood to the right atrium. The right coronary artery and the left coronary artery branch off the aorta (just after it leaves the heart) to deliver oxygen-rich blood to the heart muscle. These two arteries branch into other arteries that also supply blood to the heart. The cardiac veins collect blood from the heart muscle and empty it into a large vein on the back surface of the heart called the coronary sinus, which returns the blood to the right atrium. Because of the great pressure exerted in the heart as it contracts, most blood flows through the coronary circulation only while the ventricles are relaxing between beats (during diastole). Like any other tissue in the body, the muscle of the heart must receive oxygen-rich blood and have waste products removed by the blood. The right coronary artery and the left coronary artery, which branch off the aorta just after it leaves the heart, deliver oxygen-rich blood to the heart muscle. The right coronary artery branches into the marginal artery and the posterior interventricular artery, located on the back surface of the heart. The left coronary artery (typically called the left main coronary artery) branches into the circumflex and the left anterior descending artery. The cardiac veins collect blood containing waste products from the heart muscle and empty it into a large vein on the back surface of the heart called the coronary sinus, which returns the blood to the right atrium. 