Circulation

  • Circulatory insufficiency
  • Treatment of heart failure
  • Artificial circulation
  • Circulation is the movement of blood through the circulatory system (in arteries, capillaries, veins).
    Circulation provides the gas exchange between the body tissues and the external environment, metabolism, humoral regulation of currency and transfer formed in the body heat. The circulation is necessary for normal activity of all body systems. For the movement of blood through the vessels of the required energy. Its main source is the activity of the heart. Some of the kinetic energy, resulting in ventricular systole, spent on the movement of blood, the rest of the energy is converted to the potential shape and are used for stretching the walls of the arteries. Eviction is from a blood system, a continuous flow of blood in the capillaries and moving it in venous bed achieved through blood pressure. Blood flow through the veins caused mainly by the work of the heart, and periodic fluctuations of pressure in the chest and abdominal cavities due to the work of respiratory muscles and changes in external pressure on the wall of peripheral veins by skeletal muscles. Important role in venous circulation play venous valves prevent backward flow of blood through the veins. Diagram of human blood - see Fig. 7.

    the circulatory system of the man in the pictures
    Fig. 7. Diagram of human blood: 1 - capillary network of head and neck; 2 - aorta; 3 - capillary network of the upper limb; 4 - pulmonary vein; 5 - capillary network of light; 6 - capillary network stomach; 7 - capillary network spleen; 8 - capillary network of bowels; 9 - capillary network of the lower limbs; 10 - capillary network kidneys; 11 - portal vein; 12 - capillary network, liver; 13 - the lower hollow vein; 14 - the left ventricle; 15 - right ventricle of the heart; 16 - the right atrium; 17 - left atrium; 18 - pulmonary trunk; 19 - the superior Vena cava.
    the scheme portal circulation
    Fig. 8. The scheme portal circulation:
    1 - splenic vein; 2 - the inferior mesenteric vein; 3 - upper mesenteric vein; 4 - portal vein; 5 - branching of blood vessels in the liver; 6 - liver Vienna; 7 - the lower hollow vein.



    The circulation is regulated by diverse reflex mechanisms, among which the most important are depressant reflexes arising from the irritation special cardiotonic and sinocarotidna receptor areas. Impulses from these zones enters the vasomotor centre and the centre for regulation of cardiac activity lying in the medulla. The increase of blood pressure in the aorta and carotid sinus leads to reflex reduction in the incidence of activity in the sympathetic and strong in the parasympathetic nerves. This leads to decrease the frequency and force of heart contractions and reduced tonus of vessels (particularly arterioles), which ultimately leads to a fall in blood pressure. A significant role in the regulation of blood circulation play reflexes with chemoreceptor zones of the aorta. Adequate annoyance for them are changes in the partial pressure of oxygen, carbon dioxide and hydrogen ions in the blood. The reduced oxygen levels and increased levels of carbon dioxide and hydrogen ions causes a reflex stimulation of the heart. Coordination circulation is carried out by the Central nervous system. An important place in the regulation of blood flow belongs to the highest vegetative and bulbar centers regulation of cardiac and vascular tone. Among the adaptive changes of blood circulation includes the use of blood depots. Blood depot is the authorities, which have in their vessels significant number of red blood cells, not taking part in circulation. In situations that require higher oxygen supply to tissues, erythrocytes from the vessels of these bodies arrive at the overall flow.
    Adaptive mechanism in the circulatory system is collateral circulation. Collateral circulation - circulation of the body (bypassing off vessels) due to the formation of a new or significant expansion of existing vascular network. The adaptive mechanisms is the increase cardiac output and change of regional blood circulation. Minute volume - the amount of blood in litres coming in 1 minute from the left ventricle to the aorta and equals systolic volume on the number of heartbeats per 1 minute. Systolic volume - the amount of blood pumped by the heart ventricle with each systole (contraction). Regional circulation - blood circulation in certain organs and tissues. An example of regional blood flow can serve as the portal circulation to the liver (portal circulation). The portal circulation system to supply blood to the internal organs of the abdominal cavity (Fig. 8). Arterial blood abdominal organs are supplied with celiac, mesenteric and the splenic artery. Then the blood passing through the capillaries of the intestines, stomach, pancreas and spleen, goes into the portal vein. From the portal vein, passing through the hepatic circulation, the blood is sent into the inferior Vena cava. The portal circulation is the most important blood depots in the body.
    Disorders of blood circulation diverse. They boil down to the fact that the circulatory system is unable to provide the organs and tissues of the necessary amount of blood. This disproportion between blood circulation and metabolism increases with increased activity of the vital processes - with muscular tension, pregnancy, etc., there are three types of heart failure - Central, peripheral and General. The Central circulatory insufficiency is associated with infringement of function or structure of the heart muscle. Peripheral circulatory failure occurs when a violation of the functional state of cardiovascular system. Finally, the overall cardiovascular circulatory failure is the result of a disorder of activity throughout the cardiovascular system as a whole.