Synonyms
- Latin: vas
- Greek: angio
Definition
A vessel in a body is comparable to a tube that transports the body fluids lymph and blood. Depending on which fluid flows through this pipe system, a distinction is made between: All pipe systems in which other body fluids are transported are called “ductus” (lat. Ductus). This includes for example the lacrimal duct, glandular ducts, etc.
- Blood vessels and
- Lymph vessels.
Blood vessel
The blood vessel can be imagined as a flexible tube in which the blood of the body is transported. The individual blood vessels in the human body join together to form the complex blood circuit. The heart pumps oxygen- and nutrient-rich blood through these vessels to the periphery and from there the oxygen- and nutrient-poor blood returns to the heart.
Classification
The blood vessels are divided into:
- Aorta (main artery),
- Arteries (arteries),
- Arterioles (small arteries),
- Capillaries (hair vessels),
- Venules (small veins),
- Veins (blood vessels),
- Upper/lower caval veins (superior/inferior vena cava)
The vessel wall of larger blood vessels is basically made up of three different layers: Capillaries have a simpler structure. Around the thin endothelium pericytes branch out, which are slightly modified contractile cells of the connective tissue. They also have the property of permeability, which other blood vessels do not have.
This means that they are permeable for certain blood cells and molecules. Intima: This is the innermost layer of the vascular wall of the arteries, veins and lymph vessels. It consists of endothelial cells that have arranged themselves longitudinally towards the vessel.
Their task is the exchange of gas, fluid and substances between blood and surrounding tissue. In addition, there is a subendothelial layer and a fenestrated or elastic layer (lat Membrana elastica interna). Veins still have a venous valve, which consists of two crescent-shaped sails that have their own connective tissue layer.
The venous valves catch the blood flowing backwards and thus ensure a continuous flow of blood to the heart. The media: It is composed of smooth muscle cells, elastic fibers and collagen. Depending on the type of vessel, the tunica media has a more or less pronounced muscle layer, which is delimited inside and outside by a sheath of elastic connective tissue.
Two types of arteries can now be distinguished: Above the media lies the Membrana elastica externa as a demarcation to the adventitia. The veins are actually the same in structure as the media. The only difference is the much thinner muscle layer.
The adventitia: It serves to embed and stabilize the vessel in its environment. For the most part it consists only of loose connective tissue, except in larger vessels it contains thin blood vessels, Latin Vasa vasorum, which are responsible for supplying the vascular wall. This is not necessary for smaller blood vessels, as the supply comes from the lumen of the vessel itself.
- Tunica intima – Intima
- Tunica media – Media
- Tunica externa or tunica adventitia – Adventitia
- The arteries close to the heart of the elastic type, which are important for the wind chamber function and
- The arteries further away from the heart of the muscular type.
