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What is the Biggest Blood Vessel in the Body?

The biggest blood vessel in the body is the aorta, an artery that emerges from the left ventricle of the heart and ultimately, through its various branchings, supplies blood to every organ of the body except the lungs.

  1. Function

    • As an artery, the aorta moves oxygen-rich blood from the heart to cells and tissues elsewhere in the body. It is, in fact, the only artery that leaves the left ventricle of the heart. As such it is the ultimate origin of every other artery in the body, except the pulmonary arteries (which bring deoxygenated blood from the right ventricle of the heart to the lungs, where it is reoxygenated), making it the root of the systemic artery system.

    Segments

    • The aorta is traditionally split into three or four segments. The first of these is the ascending aorta, the segment of the aorta the flows directly out of the heart, flowing upward. The coronary arteries, supplying blood back to the heart, branch off the aorta here. The second segment of the aorta is the aortic arch, which curls around the trachea--the arteries supplying blood to the arms, head and neck branch off of this portion of the aorta. The remainder of the aorta is the descending aorta, which is further divided into the thoracic aorta, the portion above the diaphragm, and the abdominal aorta, the portion below the diaphragm, until the aorta divides into the iliac arteries, supplying blood to the pelvis and legs.

    Features

    • The aorta is considered an elastic systemic artery, which means that it expands and contracts rather significantly with the blood flow through it, it carries oxygenated blood and it carries blood away from the heart. This category applies to most arteries more than 10mm in diameter. The elasticity is essential in these larger vessels to cope with the changes in blood pressure that occur within the vessel. Nowhere is this more true than the aorta, which is directly fed by each heartbeat, and channels blood with the greatest pressure differences as a result.

    Size

    • The average diameter of the aortic root (the aorta at the point where it emerges from the left ventricle of the heart) is around 25mm in men and 22.5mm in women. The aorta decreases in diameter as it continues away from the heart, losing blood to the various arteries that branch away from it to carry blood to different destinations, and is only about 17.5mm in diameter in the lower abdomen. As for length, the ascending aorta averages around 5cm, and the others are even more variable, depending on the actual route the aortic arch takes, and the height of the individual.

    Disorders

    • There are a number of conditions which can afflict the aorta. Perhaps the most common is the aneurysm, which occurs when the aorta bulges or swells in a particular location to significantly more than its usual diameter--typically, around 4cm is considered an aneurysm. Aneurysms themselves can cause a great deal of pain and discomfort, although they can also be asymptomatic. The greatest danger presented by them, though, is the likelihood of rupture that they represent, which can cause extensive internal bleeding and rapid death.

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