General angiology

The blood circulating in the vascular system, carries nutrients from the intestines and oxygen from the lungs to every cell of the body, where are the processes of oxidation and metabolism. The metabolic products (metabolites) also come from the tissues into the blood and through the excretory organs leave the body. In the blood are necessary for life hormones and enzymes. The life of the body is possible in the case if there will be continued delivery of blood essential nutrients and oxygen to the cells and as a continuous removal of metabolic products and carbon dioxide. Nutrition, breathing, and the selection is a necessary function of cells. They unthinkable without moving substances in the body through the blood and lymph systems. Therefore, the study of ways of conducting of blood and lymph circulation of blood vessels and the heart which move blood through a closed circuit of pipes, is important not only in theoretical terms, but is dictated by practical requests medicine. This is due to the fact that the defeat of the various parts of the cardiovascular system of the pathological processes are quite frequent. Sometimes these changes are so significant that they should be conservative or surgical treatment of patients.
It is now established that in the process developed and functioning of human body cardiovascular system depending on the functions of organs and systems continuously rebuilt structurally and functionally. Therefore physicians of various specialties, you need to know morphological and physiological features of the heart and blood vessels. A clear diagnosis of the disease of the heart, arteries or veins are quite difficult, because these violations are multifaceted. They can be expressed in various destructive lesions valves, muscles and blood vessels of the heart, violations of hemodynamics in large, medium and small arterial and venous vessels, change of permeability and innervation of the vascular wall and others On the development of various vascular diseases have a huge impact diseases of blood and blood rheological properties, for vessels and their contents are in close functional relationship. Consequently, the structure of the heart and blood vessels, the distribution of blood vessels in the organs, topography and their projection on the surface of the body, are an issue that is required in the preparation of a doctor.
The value in the circulation of the heart, arteries, arterioles, capillaries, venules, veins and the degree of their participation different.
Heart, Contracting rhythmically, causes the movement of blood through the arteries, capillaries and veins. Capillaries and arteriovenous anastomoses combined arterial and venous vessels. Metabolism and nutrition of tissues are made by penetration through endothelial capillary walls in the tissue of nutrients and oxygen. From the tissues into the capillaries do different metabolites metabolism.
Among the arteries and veins there are major vessels: the aorta, pulmonary trunk, upper and lower hollow vein and smaller vessels, which are the branches of the great vessels. The branches of the great vessels are divided into neorganika and blood. Neorganika vessels go from major vessel to the place of confluence of the body. As a rule, neorganika vessels presents no one, and sometimes multiple trunks. Blood vessels consistently branched on artery 1 St, 2 nd, 3 rd, 4-th and 5-th order; the last order branch ends with the arterioles. The number of orders branching artery subject to fluctuations. Some authorities, such as in lungs, kidneys and other, from these arteries begin a major branch named segment. Arterioles disintegrate into a capillary network from which are formed venules, which is the beginning of the venous system.
Vienna formed by the merger of venules in Vienna on 1-St order. Vienna 1-th order drawn in Vienna of 2-nd, 3 rd, 4-th, 5-th order, etc. a person total number and total capacity of the venous system in 3 - 4 times more than arteries. This is because for a time unit in the arteries passes more blood than through the veins. The veins are not only perform the function of carrying out blood from the periphery to the heart, but are depot for venous blood. Many arteries of the limbs and trunk often accompanied by two veins or even form a venous plexus around arteries. Characteristic of the arteries is reduction of diameter as they branching, and in the venous system as a merger of small veins are formed larger venous vessels.
A characteristic feature of the vascular system are collaterals. When a well-developed collaterals and blood plexus in cases of circulatory disorders provides better blood supply of organs. The closer to the arterioles, capillaries and venules, the more is revealed in the vascular system anteriormedially. arteriovenous and venous-venous anastomoses.
Anteriormedially anastomoses are of mutual connection of the arteries of different caliber, originating from different arterial sources. Thanks to these anastomoses possible collateral (bypass) road blood circulation to the body or body part. These anastomoses well expressed in the vascular plexus around joints, internal organs (intestines, complex gland). Significantly develop collateral vessels in cases where one of the main sources of blood supply to the organ trombones or long squeezed. To compensate for the blood flow to the organ anastomoses blood vessels dilate and communicate with other vessels, creating additional sources of blood supply.
Arteriovenous anastomoses mainly detected between arterioles and veins, representing another feature than anteriormedially anastomoses. Through arteriovenous anastomoses rapid transition blood (bypassing the capillaries) from arteries to veins. The availability of such communications is a good compensatory mechanism to ensure the adaptability of the vascular system to a rapid redistribution of blood flow in the body.
Venous-venous anastomoses are between venules and larger veins. As a result of these compounds in the thickness of the body or in the tissue surrounding the body, formed venous plexus, acting depot blood.
All parts of the vascular system (large trunks, extraorgan and intraorgan vessels, arterioles, capillaries and venules) are in close functional unity, established by the vegetative nervous system and hormones in the endocrine system. To do this, the body has a very sensitive and delicate mechanisms of blood pressure regulation. Depending on the level of metabolism is supported and certain blood pressure with the necessary capacity vascular system, with an appropriate number of functional capillaries. But in other organs, where the currency is low, the blood vessels are narrowed and capillaries sopostavit. This constant regulation of circulation is ensured by reflex activity of vegetative parts of the nervous system. In the vascular wall sympathetic (vasoconstrictor) fibers form plexus, which nerviruet smooth muscles, causing them to fall. When you turn off or inhibition of sympathetic innervation dilate blood vessels. It is expected that some vessels, in addition to the sympathetic innervation, and they are innervated by the vasodilator (parasympathetic) fibers, irritation which leads to dilation of blood vessels.
The impulses from the Central nervous system, formed in vasomotor center, which operates under the control of impulses, coming to the vessels on the autonomic nerves, and make the reflexes of the cardiovascular system. Vasomotor center is a functional set of nerve cells within the brain stem, which are connected with blood vessels afferent nerve fibers - Baro-, chemo-, Intero - and exteroreceptors. The peripheral end of afferent nerve fibers, such as baroreceptor, originates in the walls of blood vessels (arch of the aorta, thoracic and abdominal aorta, place of division of the common carotid artery, pulmonary artery, and the lower hollow vein and others). When high blood pressure in the blood vessels comes irritation of nerve endings afferent nerves that leads to reflex decrease or increase blood pressure using a vasodilator or sossoudossoujiwate nerves.
In the process of life is constantly reflex changes of the heart that causes and reflex restructuring the tone of the vascular system.
In the walls of blood vessels also laid afferent fibers of chemoreceptors that react to the presence in the blood of different chemicals and hormones. When irritation of the nerves of the chemoreceptor impulses are transmitted to the Central nervous system, where the vessels receive a reflex response in the form of a vasoconstrictor or vasodilator pulse. In addition to the impulses emanating from the cardiovascular system, you experience a return reflexes (paired) at the irritation of the receptors located outside the cardiovascular system. Reaching sensitive centers, they switch on the vasomotor center. The pulse of the centre cause certain functional changes in the cardiovascular system.