Anatomy-Lexicon

Types of arteries

Synonyms

Artery, artery, pulse artery, artery, blood vessel, vessel

English: artery

introduction

After that in the middle layer (Tunica media) the predominant microscopic construction material of the artery, one differentiates between two types of arteries. Arteries of the elastic type are mainly the large arteries near the heart. These include the main artery (aorta) and the pulmonary arteries (Pulmonary arteries) with their large outflows. All other subsequent arteries are of the muscular type. The transition between the two types is fluid and microscopic (histologically) not always precisely delimitable.

Muscular-type arteries (Arteriae myotypicae)

The group of arteries of the muscular type includes all arteries except the largest arteries (aorta and Pulmonary arteries). These arteries are named because there are in the middle layer (Tunica media) mainly smooth musculature is located. Arterial vessels with only one muscle layer are called one Arteriole.

The innermost layer (Intima, tunica intima) is known as Endothelium. This endothelium is a single-layer, complete covering of flat cells. These cells are aligned parallel to the blood flow and thus promote the blood flow. The individual cells in this layer are very closely connected (Tight junctions, zonula occludens) and thus control the barrier between the interior of an artery and the environment.

The smooth surface of the innermost layer (Endothelium) prevents components of the blood (White blood cells, Platelets, Red blood cells) can deposit on the wall. Over the surface of the endothelium, various Proteins released into the blood to counteract the formation of blood clots.
There is also one at the transition from the inner to the middle layer subendothelial Layer. This layer changes with age and is the main reason for Hardening of the arteries (atherosclerotic vasoconstriction) in old age.
The middle layer (Media, Tunica Media) is the widest layer of the arterial wall and consists almost entirely of smooth muscle cells. These muscle cells are arranged in flat spirals and open through tiny openings (Gap junctions) connected with each other. The muscle cells of the media create (synthesize) a two-dimensional wickerwork made of many elastic fibers, the so-called membranes elastica interna. Since this membrane is penetrated by many small openings, it favors the passage (diffusion) of various substances through the vessel wall.
The outermost layer of the artery (Adventitia) consists of connective tissue that firmly anchors the artery to its surroundings. The nerves and blood vessels (Vasa vasorum), which supply the vessel wall, are also located in the adventitia. The inner layers of the vessel wall are supplied directly by the blood flowing through the artery.

Illustration of an artery

Figure small artery: scheme of the wall construction

Outer layer of
Arterial wall -
Tunica externa
Outer elastic layer -
External elastic membrane
Middle layer of the arterial wall -
Tunica media
Inner elastic layer -
Internal elastic membrane
Inner layer of the arterial wall -
Tunica intima
Endothelial cells - Endotheliocyti
Blood vessels in the adventitia -
Vasa vasorum
Autonomous nerve plexus of the
Vessel wall -
Vascular plexus

You can find an overview of all Dr-Gumpert images at: medical illustrations

Elastic-type arteries (arteriae elastotypicae)

Arteries of the elastic type are above all the arteries near the heart such as the main artery (aorta) and pulmonary arteries (arteriae pulmonalis). The decisive difference to arteries of the muscular type is the structure of the middle layer (media). Few muscle cells are found in elastic-type arteries sandwiched between a large layer of elastic lamellae. Depending on how tight the muscle cells are, these arteries are given different degrees of tension.

The different structure of the middle layer (Media) can therefore be explained by the fact that the arteries near the heart fulfill a wind chamber function. At the Heartbeat the blood is pumped out of the heart with great force and hits the vessel walls of the arteries near the heart with relatively great force. Since these vessel walls consist of many elastic lamellae, this strong blood ejection can be cushioned and thus the blood flow can be converted from a turbulent into a continuous flow. This movement of the vessel wall continues through all arteries and is, for example, am wrist felt as a pressure pulse.

Barrier arteries (arteria convolutae)

Barrier arteries can restrict the vessel width so much that little or no blood can flow through the vessel. This can be used to regulate the blood supply to various organs. This regulation of the artery is of particular importance in the human body for the sexual organs and for many endocrine glands.