Aorta: Structure, Function & Diseases

Without it nothing works: the aorta, medically also called aorta, forms the outflow tract from the heart to the branching into the pelvic and leg arteries and works, so to speak, “at high pressure” on the blood supply of the entire organism, around the clock, 365 days a year, for many decades. One should therefore take care of one’s aorta, so that even in old age this task passes by reasonably without a trace.

What is the aorta?

The aorta is the largest artery in the human body and the starting point of the entire blood supply. It arises from the left ventricle of the heart, is then about 2.5-3.5 cm wide in diameter in adults, and runs in a “walking stick” shape for a length of 30-40 cm until it branches into the iliac arteries. All of the body’s blood must pass through this blood vessel before it is then further distributed to the head, arms, abdomen and legs.

Anatomy and structure

The anatomy is the same in all people except for minor variations: The aorta originates in the left ventricle, the “high-pressure system” of the heart, and initially runs headward, where it then arcs above the heart in the middle of the chest to the left side of the body and eventually slopes downward and passes downward through the chest and abdomen on the left side in front of the spine. The first blood vessels to leave the aorta are the coronary arteries, and then along the aortic arch the supplying vessels for the arms and head depart upward. In its further course, the aorta supplies the individual rib segments and the entire abdominal cavity with blood via defined outlets before it divides into the right and left iliac arteries at the so-called “aortic bifurcation” at about the level of the navel. These then continue downward to reach the pelvic cavity and legs.

Function and Tasks

The function of the aorta is to supply blood to the entire body, in which oxygen and nutrients are delivered and metabolic waste products can be removed. In order to be able to ensure this supply even against the force of gravity into the head or during the heaviest physical exertion down to the last muscle cell, the heart must build up a tremendous pressure, the arterial blood pressure. In a healthy adult, this should be around 120/80 mmHg, i.e. a maximum of 120 centimeters on the mercury column, a historically medical measuring instrument. The aorta now has to withstand this pressure and carry it away to the periphery, if possible without major reductions. For this purpose, the wall of the aorta is somewhat expandable, especially in its arcuate course, so that it can build up a kind of pressure reservoir even in the millisecond intervals when the heart is not actively pumping. The wall’s distensibility is thus important to ensure function and is severely compromised by calcification of the vessel wall (arteriosclerosis).

Diseases and ailments

The insidious thing about diseases of the aorta is that the affected person often does not notice them until it is already too late. They are mostly asymptomatic, meaning “without symptoms.” The basis of these life-threatening clinical pictures is mostly arteriosclerosis and high blood pressure. Calcification of the arterial wall impairs its distensibility, narrows its diameter and possibly displaces vascular branches to vital organs, such as those of the abdominal cavity. The latter can lead, for example, to regularly recurring abdominal pain after eating, i.e., when the intestine needs a lot of blood for digestion and cannot get it due to the narrowed vessel. The calcification and narrowing of the aorta then subsequently leads to a reaction of the heart, which increases blood pressure in order to still ensure the supply of blood to the body through the narrowed aorta. This, in turn, damages the vessel wall even more – creating a vicious cycle. Two immediately life-threatening emergencies are “aortic dissection” and “ruptured aortic aneurysm.” In dissection, blood burrows through calcified wall districts into the vessel wall, obstructing both the vascular outlets to the brain and the aorta itself. Sudden onset of sharp chest or back pain with no previous history is an urgent reason to call an emergency physician immediately! An aortic aneurysm, on the other hand, is a bulging of the vessel wall due to high blood pressure, which usually develops in the abdomen and often goes unnoticed for years.However, the bulge thins the vessel wall of the aorta so that it eventually tears, i.e. “ruptures”. A possible consequence is internal bleeding, which only becomes noticeable through pain when it is already too late. Risk factors such as high blood pressure, high blood lipid levels, smoking and diabetes mellitus should be avoided or treated for this reason.