for serviceable work fuel, and a human body here not an exception is required to Any car. Our main fuel oxygen - is carried by blood to all bodies and fabrics on highways of rather effective transport network - systems blood circulations.
Blood Circulating in vessels not only supplies an organism with fresh oxygen and necessary nutrients, but also deletes potentially harmful products of an exchange, including carbonic gas from cages. This process of delivery-removal should occur continuously. The matter is that all 5-litre stock of blood of the average adult person contains no more litre of oxygen. It will suffice for maintenance of a life within 4 minutes at rest and only 1 minutes - at physical activities. Besides blood cannot give to fabrics all oxygen, therefore, delivering it to the address and having taken away cargo of a waste, it immediately starts on a journey after new portion.
blood circulation System
The Major component of blood circulation - heart. It consists of two separate muscular pumps - right and left. Right pumps over blood through lungs where it is enriched by oxygen. Then blood arrives in the left part of heart, whence goes to a way on all fabrics of an organism. The blood sated with oxygen flows on thick-walled vessels which name arteries. From large arteries narrower branch off arterioly. Their strong walls penetrated by muscular fibres extend and narrowed, regulating speed of a blood-groove. Further they are divided into more and more small vessels up to the most thin capillaries. Their diameter does not exceed also the 100-th share of millimetre, but only here blood can perform the work.
Unlike all other vessels, a wall of capillaries pronitsaemy, and through them fabrics are supplied with oxygen and nutrients in exchange for a waste. The total area of capillary vessels of our organism makes over 6000 m - and it is too much them, that it was possible to fill all with blood at once. Therefore capillaries open and closed as required.
Having given to fabrics oxygen, blood darkens. From capillaries it gets in hardly the big vessels named nepulami which, in turn, run into veins, and those deliver blood to heart. Brain blood supply even at sharp decrease in a blood pressure, for example, in case of heavy krovopoteri.
In a network of blood vessels, as well as in any closed system, the constant quantity of a liquid should circulate. Hardly blood will start to follow from a wound, as the curling mechanism immediately will join to reduce to a minimum krovopoterju. Curling begins at contact of blood cells with air or damage of fabrics, but sometimes occurs and in blood system. This unsystematic process is called as a thrombosis. Fortunately, if the blood vessel is blocked by a blood clot, blood quite often finds roundabout a way in process kollateralnogo blood circulations. Sometimes blood clots are dissolved in vessels. If it does not occur a natural way, it is necessary to resort to surgical operation.
the Blood pressure
With each blow of the warm pump pressure of blood in arteries and arteriolah changes also. At reduction of heart it reaches the peak, or sistolicheskogo pressure, and then slowly goes down to a minimum named diastolicheskim pressure, and so a cycle behind a cycle. Pressure of blood is always expressed by two figures. At the healthy young man it usually does not exceed 120/80. Thus 120 - an indicator sistolicheskogo pressure, and 80 - diastolicheskogo. Both indicators are measured in millimetres of a mercury column. At strong excitement or heavy physical activity pressure can raise for a short while, but soon settles into shape. The blood elevated pressure is constant happens a consequence of some illnesses or gradual ageing of an organism. At physicians it is considered to be the person the hypertensive person if it sistolicheskoe pressure constantly exceeds level 100 plus age of the patient, and diastolicheskoe - it is invariable above 100. The bottom limit of norm for the healthy adult person considers an indicator 80/40. Low pressure is abnormal arises at strong krovopotere, heart attack or at a terminal stage of many diseases. The lowest pressure of blood means that in a brain and other major bodies not enough blood arrives, and with it both oxygen, and the person is on the threshold of death. It can to be admitted, having entered the patient the medicines narrowing walls of blood vessels and raising pressure until the original cause of its recession, for example, by blood transfusion after heavy krovopoteri will be eliminated.
The Reason be abnormal a high blood pressure the tumour of adrenal glands for at this illness in blood superfluous adrenaline arrives can. This hormone is developed nadpochechnymi by glands located over the top poles of kidneys. It stimulates warm activity, raises pressure and strengthens blood supply of muscles. Usually its development increases at sharp physical activities or a strong fright, but constant presence at blood of the big dose of adrenaline conducts to hypertension development. Pressure of blood can raise and in case of damage of one or both kidneys when they develop surplus renina - enzima, supporting their blood supply.
The High pressure injures artery walls, and in places of the begun to live traumas hems narrowing a gleam are formed. As a result pressure continues to grow, and blood supply of fabrics is broken. Suffered from shortage of blood the kidney starts to develop more repina and brings the mite in pressure growth. Total action of these factors is capable to lead to a heart attack for at a high pressure heart does not cope with swapping of blood from lungs in other bodies of a body.
From a high pressure the blood vessel in an eye or a brain that means blindness or a stroke can burst. Treatment of this illness at the earliest stages considerably reduces risk of complications. To result pressure in norm it is possible, having removed a tumour of an adrenal gland or one sick kidney. Other forms of a hypertension are treated by means of medicines.
The Population of the rich western countries with their high standard of living and abundance of products subjects the arteries to an extra risk. arterioskleroz, pli loss of elasticity of walls of arteries, begins as a result of occurrence on them of fatty adjournment, mainly in the form of cholesterol. In process of its accumulation internal walls of vessels become covered by plaques to which the small blood cells named trombotsitami stick. Walls of arteries are gradually condensed and lose elasticity, their gleam is narrowed, and the blood-groove weakens. All is process leads to blood pressure growth though also itself partly can be its consequence. At arterioskleroza there is no unique reason, but it, apparently, is a hereditary illness and is more often meets at people excess weight, at those who conducts an inactive way of life, uses fat food, is exposed to stresses or smokes.