The Aorta: Valves & Anatomy

Instructor: Jennifer Szymanski

Jen has taught biology and related fields to students from Kindergarten to University. She has a Master's Degree in Physiology.

The aorta is the largest artery in the body. In this lesson, we'll explore where this important vessel travels in the body, discuss why it's so unique, and look at a few of its diseases.

Introduction

One of the jobs of the circulatory system is to deliver oxygen-rich blood to every cell in the body. It accomplishes this through an amazingly sophisticated network of arteries. Every great journey must have a starting point; and for an oxygenated red blood cell, the journey begins in the vessel called the aorta.

The aorta as visible on the heart
Image

The Aorta's Path

The aorta is the vessel that connects to the heart's left ventricle. Blood that enters the aorta has just finished traveling through the lungs to the heart, and is freshly oxygenated, ready for its journey throughout the body. This blood leaves the muscular left ventricle through a valve called the aortic valve into the ascending aorta, which leads up and away from the heart. Blood from the ascending aorta also enters coronary arteries, vessels that supply the heart muscle itself with blood. The ascending aorta next becomes the aortic arch, which, in turn, leads into several other vessels.

The parts of the aorta
Image

In many cases, arteries are named for where they are taking blood. The vessels that originate at the aortic arch are:

  • The brachiocephalic artery ('brachio' means arm and 'cephalic' means head, so this vessel ultimately takes blood to the right arm and up the right side of the neck to the brain)
  • The left common carotid artery, which leads up the neck to the brain, and
  • The left subclavian artery, which runs below (sub) the clavicle (your 'collar bone,') into the left arm

Blood then passes through the descending aorta, which leads down through the chest all the way into the abdomen, where it branches off into many vessels that go all over the body. The portion of the aorta that is located in the chest is called the thoracic aorta. Once the vessel passes through the diaphragm, (the sheet of muscle located right below the lungs and ribcage,) it's called the abdominal aorta.

This may seem like a lot of names for what really is only one long tube, but all of these names help doctors and surgeons determine exactly where there's a problem if one occurs.

Characteristics of the Aorta

If you think about the job the aorta has to do (take blood under pressure and get it to all parts of the body), then you can probably guess what characteristics it has. The aorta is very elastic, and quite wide - about an inch (2.54 cm) in diameter. Blood is under a great deal of pressure in the aorta. To help the vessel withstand this pressure, the aorta is lined with several layers of smooth muscle. This muscle also contracts to help push the blood forward.

Diseases and Problems of the Aorta

Because the aorta is such an important vessel, problems with it can be life-threatening. Although there are many diseases of the aorta, we'll briefly look at three of them.

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