The human body consists of biological tissues permeated with a mass of blood vessels. They are responsible for the nutrition of cells and the removal of metabolites, supporting their vital activity. Arteries are a type of blood vessels that carry blood directly to the capillaries. All cells of the body receive solutes from them through the interstitial fluid.
Morphology
An anatomical structure in the form of an elastic tube with a wall and a lumen is called an artery. It passes in body cavities or connective tissue veins of parenchymal organs, where it constantly gives off small branches to nourish the surrounding tissues. An artery is a vessel that constantly conducts a pulse wave.
In large vessels, its distribution is achieved mainly due to the elastic qualities of the wall, and in small ones - due to muscle contraction. Like the heart, arterial vessels are constantly in good shape andexperience periods of expansion and contraction. The muscular wall also alternates periods of contraction with relaxation.
Histological structure
Any artery is a formation with a multilayered wall, which consists of elastic fibers intertwined with each other and muscle cells embedded between them. This is how the middle wall of the vessel is arranged, which is covered with a connective tissue membrane from the inside. It is based on the endothelial layer, facing the inside of the vessel. It is a single-layer protozoan epithelium, the cells of which fit tightly with their edges in order to prevent platelet cells from reaching the connective tissue membrane. The latter contains platelet adhesion receptors, which is the basis of the mechanism of thrombus formation in case of damage to the endothelial layer.
Outside the middle shell, represented by smooth muscle cells woven into an elastic network, there is another layer of connective tissue. It serves to ensure the mechanical strength of the artery. What is it in terms of histology? This sheath is a strong network of collagen fibers embedded with single cells. It is connected to a looser adventitia that connects the artery to the stromal tissue of the parenchymal organs.
Regulation of arterial tone
All arterial vessels of the body have their own circulation, since only the endothelium can feed on the blood in their lumen. These vessels and nerves pass through the outer connective tissueshell and blood supply to the middle layer - muscle cells. The smallest nerves of the autonomic system also go to them. They transmit sympathetic impulses that accelerate the conduction of the pulse wave as the heart rate increases.
In addition, the artery is a hormone-dependent structure that expands or contracts depending on the presence of humoral factors: adrenaline, dopamine, norepinephrine. Through them, the body regulates the tone of the entire vascular system. The main goal is to quickly increase blood flow to the muscles by dilating the blood vessels of the periphery in case of suprathreshold stress. This is an evolutionary mechanism for saving the life of an organism by fleeing from danger.
Main arteries of the body
The largest artery that can withstand maximum pressure is the aorta - the main vessel from which regional branches depart. The aorta originates in the left outflow tract of the corresponding ventricle. The pulmonary artery originates in the right outflow tract of the heart. This system demonstrates the separation of circulation circles: the aorta carries blood into a large circle, and the pulmonary trunk into a small one. Both of these vessels take blood away from the heart, and the veins deliver it to it, where the circulatory system is crossed.
Among the most important arteries of the body are the renal, carotid, subclavian, mesenteric, iliac arteries and vessels of the extremities. Albeit not the largest, but extremely important for the body, coronary arteries stand separately. What does this mean and why are theyspecial? Firstly, they nourish the heart and form two mutually perpendicular circles of blood circulation of this organ. Secondly, they are special because they are the only arterial vessels that fill in ventricular diastole before the development of the pulse wave of the ascending aorta.
