The Role of Arteries in the Circulatory System

Supplying the Body with Blood, Oxygen, and Nutrients

Comparison of Arteries (left) & Veins (right).

Arteries are blood vessels that carry blood away from the heart to the rest of the body. They are shaped like tubes and branch into arterioles to reach the organs and tissues. The pumping contractions of the heart propel the blood through the arteries.

Circulation

The main artery of the systemic circulation is the aorta. It is attached to the left ventricle of the heart and carries oxygenated blood.

The aorta branches into arteries that go to different organs and parts of the body. You can feel your pulse in an artery such as the carotid artery in the neck or the radial artery in the wrist.

The pulmonary artery differs from the others in that it is attached to the heart's right ventricle and carries blood that is poor in oxygen to the lungs. There, it branches into arterioles and capillaries so the blood can take on oxygen before returning to the heart via the pulmonary vein. This oxygenated blood enters the left atrium and is pumped to the left ventricle and out through the aorta.

Structure

Arteries contain a high percentage of a special type of muscle, called smooth muscle, that can be controlled by hormones and special signals from the nervous system. The outer layer of an artery is made of collagen fibers. The middle layer has smooth muscle and elastic fibers. The inner layer is the lining called the endothelium.

Blood travels through the hollow center of the arteries. If this hollow center becomes constricted due to overdevelopment of the muscle or the formation of plaques, it can raise blood pressure. Plaque also makes the arteries less flexible. If an artery ruptures or is blocked, such as in a stroke or heart attack, the tissues that it normally supplies will die.

The thick, strong walls of arteries make them able to resist the high pressures that exist near the heart. All of the major organs in the body have their own special kind of arteries which are uniquely structured to deliver the supplies needed.

The heart muscle is supplied by the coronary arteries. The left coronary artery and the right coronary artery branch off of the aorta and the left coronary artery further divides into the circumflex artery and the left anterior descending artery. These four arteries are the ones that may be replaced in coronary artery bypass graft (CABG) surgery. A quadruple bypass replaces all four arteries.

Arterial Health

Hardening of the arteries is the common term for atherosclerosis and peripheral arterial disease (PAD). This occurs when plaque forms from fat, cholesterol, calcium, protein, and inflammatory cells, narrowing or blocking the arteries. When this happens in the arteries of the heart, it is coronary artery disease (CAD). Risk factors for PAD include smoking, diabetes, high blood pressure, and high cholesterol. PAD can lead to heart attack, stroke, transient ischemic attack, renal artery disease, and amputation.

Sources:

Heart & Blood Vessels: Your Coronary Arteries. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/heart-blood-vessels-coronary-arteries.

How Does the Blood Circulatory System Work? ​U.S. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072434/

Peripheral Artery Disease (PAD). Cleveland Clinic. https://my.clevelandclinic.org/health/articles/peripheral-arterial-disease

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