Many substances must be distributed throughout the body for the maintenance of vital functions. Since these substances are unable to make their way within a time compatible with life on their own, nature created blood for this task. This is a fluid that circulates through the body in a fixed vascular system, distributing oxygen and other substances throughout the body. In this circulation, from a functional and anatomical point of view, physicians distinguish two types of vessels: Arteries and Veins.
What are arteries?
Arteries basically have the task of transporting oxygen-rich blood, which is expelled by the heart, to the remote regions of the body. There, the oxygen is delivered to the surrounding tissues, as the cells need it to perform their function and not die. These processes produce carbon dioxide, which is absorbed into the blood in exchange for oxygen and transported to the lungs, where it is subsequently exhaled. This return transport of blood to the central regions of the body takes place through the veins. They contain 80 percent of the total blood volume, which is normally four to six liters. So, conversely, only 20 percent of the blood is in the arterial system at the same time.
Anatomy and structure
The arterial system can be anatomically divided into large and small arteries, into arterioles and into capillaries. Characteristically, as it progresses to the periphery, the diameter of the arteries continuously decreases until scientists eventually speak of arterioles, which at the terminus of the arterial system merge into the capillaries, which in turn serve to exchange substances with the surrounding tissue. If you look at the cross-section of an artery under a microscope, you can see that they are made up of three layers. Inside, i.e. closest to the blood, there is a simple layer of cells, which in technical terms is called the endothelium. Around the endothelium, a muscle layer can be seen as the second layer, which is bordered on the outside by connective tissue. This represents the third layer in the construction of an artery. The muscular layer plays an important role in the function of an artery and varies, depending on the distance from the heart. Arteries close to the heart are extremely elastic due to stretchable elements called filaments, which are found in the muscular layer. Far from the heart, contractile elements predominate, so arteries are said to be of the muscular type.
Functions and tasks
Arteries, of course, serve to carry oxygen-rich blood to the periphery of the body. This is done under the high pressure built up by the heart, which is also called blood pressure. The arteries near the heart are extremely elastic, as discussed above, so that they can absorb excessive fluctuations in blood pressure, which damage the arteries in the long term. The scientific name of this effect, which can be observed mainly in the aorta, is the Windkessel effect. The arteries located far from the heart are mainly classified as muscular type. The capillaries would burst at the high blood pressure that prevails in the aorta. Therefore, it must be lowered by the muscular arteries far from the heart and consequently these are called resistance vessels. The capillaries now have the task of mass transfer. Oxygen and carbon dioxide are exchanged with the surrounding tissue. In addition, the liquid components of the blood, the blood plasma, pass into the tissues. From this point on, the plasma is called lymph and has the task of supplying cells that do not have a direct connection to the vascular system.
Diseases
A very significant disease of the arteries is called arteriosclerosis. This occurs, for example, in connection with cigarette consumption, stress or malnutrition. Over the years, deposits occur inside the arteries, which reduce the elasticity of the vessel and decrease the cross-section. One consequence of these two effects, for example, is the potentially fatal heart attack, in which clogged coronary arteries prevent parts of the heart muscle from being supplied with oxygen. In addition, atherosclerosis can lead to high blood pressure, which over the years increases the risk of vessels bursting. This can happen in the brain, for example.In this case, one speaks of a stroke, which can lead to paralysis, sensory deficits and in the last consequence also to death.
Typical and common diseases
- Arterial circulatory disorders in the feet and legs.
- Arterial hypertension
- Arterial occlusive disease
- Peripheral arterial occlusive disease
