The heart is a pump with four chambers; the top chambers, the left and right atria, are the entry point into the heart for blood. After blood moves down into the left and right ventricles, it's pumped out and away from the heart. Blood leaves the ventricles via two arteries, the aorta from the left ventricle and the pulmonary artery from the right ventricle.
Aorta
The aorta is the artery that carries blood from the left ventricle of the heart. The aorta is the largest blood vessel in the body, understandable because it supplies the entire body with oxygenated blood. The aorta is attached to the left ventricle of the heart, which is filled with newly oxygenated blood from the lungs.
The aorta forms an arch with three branches that supply the upper body exiting the top: the brachiocephalic, sometimes called the innominate artery, the subclavian and left common carotid arteries. These three branches supply the head and upper body. As the aorta turns downward, toward the abdomen, it's called the descending aorta; this artery branches out to supply the internal organs and then the entire lower body with oxygen.
Coronary Artery
The coronary artery branches off the aorta right after it leaves the heart. The coronary arteries return oxygenated blood to the heart muscle and tissues. Coronary arteries are the arteries associated with heart disease. Coronary arteries are the blood vessels that can become clogged with plaque made up of fat, calcium and dead cells, explains KidsHealth, the online website of the Nemours Foundation. The clogging of the blood vessels hinders blood flow and can cause coronary artery disease. Coronary artery disease can lead to myocardial infarction, or heart attack.
The coronary artery divides into two branches, the left main coronary artery and the right coronary artery. The left main coronary artery branches into the anterior descending artery, or LAD, and the circumflex artery.
Pulmonary Artery
The pulmonary artery is the only artery in the body that doesn't carry oxygenated blood; instead, it returns carbon dioxide-laden, de-oxygenated blood from the right ventricle to the lungs, according to the Merck Manual. The pulmonary artery, which is tucked underneath the aortic arch, splits almost immediately after leaving the right ventricle into the left and right pulmonary arteries, which branch into smaller vessels called arterioles. Carbon dioxide is released and oxygen picked up in the capillaries, the smallest blood vessels.
