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the Heart, a bit similar the form on a pear and, perhaps, main our treasure, tirelessly pumps over blood on all body, supplying bodies and fabrics with a food and oxygen.

Our heart in size about a fist, it is asymmetrically located in a chest cavity behind a breast and almost is completely surrounded by lungs. The heart basis is approximately at armpit level, and it on 4 5 sm is displaced to the left from a median plane of a body.

the Powerful pump

Heart as if the tireless blood pump, regularly pulses, alternately increasing and decreasing in size. Each such cycle of a relaxation-reduction is called as a warm cycle. Heart represents a thick-walled hollow muscular bag. Relaxing, it is filled with blood from the blood vessels named veins, and at each compression with force pushes out blood in other vessels - arteries. Continuously pumped over blood a circle behind circle circulates on a body, carrying oxygen and nutrients in all its corners and deleting dioxide of carbon and an other waste from fabrics.

That heart was not filled with just pushed out blood, the nature has provided in it some valves. These are the rags of a strong elastic fabric attached to its internal walls similar to pockets. In the fullness of time they, as doors, open and slam, forcing blood a leak where to it follows.

Blood Flowing in one direction presses valves to heart walls, and those do not interfere with a blood-groove. But at the slightest attempt of blood to turn back, shutters of valves are inflated and block to it a way. Valves publish familiar to us deaf postukivanie, slamming at each reduction of heart not to let in blood back. And reductions own nervous system of heart - sinusno-predserdnyj knot operates.

Two in one

Our heart - completely not single-chamber pump in the form of a hollow muscular bag. In it in coordination operate the whole two pumps divided by a thick and strong muscular partition.

The Right pump (on the scheme it is shown at the left) forces obeskislorozhennuju blood in lungs on short pulmonary arteries. In lungs blood is sated with oxygen then comes back on short pulmonary veins in other part of heart - left zheludochek. It is more on the size and muskulistee than the right colleague. Its problem - to pump over the blood enriched by oxygen on an aorta and other main arteries in all parts of a body - up to finger-tips on hands and feet. Having given to fabrics the brought oxygen, blood is slowly started up in a way back on the main veins and gets in right zheludochek, ready to the next travel to lungs.

the Pulse rate

Under the pressure of blood, with force pushed out by heart at each reduction, an artery considerably extend. Further pulsing waves of pressure extend on more and more small arteries, and they are easy for probing, for example, on a wrist. Each push of blood, or pulse, is generated with one blow hearts. As the two-line pump operates not only heart as a whole, but also everyone zheludochek separately. The top chamber zheludochka is similar to an elastic thick-walled sack and is called as an auricle. It some kind of a waiting room for blood. Coming back from lungs in the left auricle, and from other organism - in right, blood fills them, as if water - a children's balloon.

Walls of both bottom chambers much more thickly and muskulistee. It also is zheludochki - the main motive power sending blood in travel on arteries.

Between each auricle and zheludochkom the big valve is located. That on the right, is called as three-folding as it is supplied by three pockets or shutters. Left name two-folding or mitralnym.

These valves force blood a leak in the necessary direction. One more steam of valves it is located in confluence places in zheludochki the main arteries. On the right - the valve of a pulmonary trunk (on a way to lungs), and at the left - the aorta valve.

Each warm cycle consists of two phases. At a relaxation zheludochki are unclenched, and from auricles through mitralnyj and three-folding valves in them the next portion of blood arrives. Thus valves of a pulmonary trunk and an aorta slam, blocking blood a way back from the main arteries. This phase of a warm cycle is called diastoloj.

a reduction Phase

The reduction Phase is called as a systole. Being compressed, zheludochki push out blood through valves of a pulmonary trunk and an aorta, and it spreads on all arteries. Thus shutters mitralnogo and three-folding valves are closed not to admit return outflow of blood.

It is useful for Each of us to know that such diastola and a systole as doctors measure pressure of blood in arteries at the reduced and weakened heart. For example, pressure 120/80 means that sistolicheskoe pressure of blood at the maximum reduction of heart is equal to 120 units, and diastolicheskoe - when the weakened heart is filled with blood - to equally 80 units. On blood pressure level, and also after frequency and filling of pulse the doctor judges a condition of heart of the patient.

How many at us blood?

At the adult person about 5 l of blood. Speed of blood circulation depends on frequency and force of warm reductions.

At the baby heart, as a rule, fights more often, than at the adult. The heart of the newborn kid, weight is no more 20 g and size about a strawberry berry, fights with frequency of 120 blows in a minute. By 10 years palpitation is slowed down to 90 blows. Heart of the average adult person weighs 300 g (as 2-3 apples), and at men fights with frequency about 70 blows in a minute, and at women - nearby 80.

With each reduction heart pushes out of 70-80 ml in an artery of blood. Approximately 12 blows are enough to fill with blood a standard litre package from under orange juice. For 15-20 minutes heart can fill with blood the whole bath, and in an hour pumps over without small 350 litres - it will suffice to fill petrol tanks of several cars.

However all these figures are true, if the person is at rest. As soon as you start to move, frequency of warm reductions immediately increases, and with it - and volume of pumped over blood. At the big physical activities heart is reduced with frequency over 150 blows in a minute, pumping over with each blow more than 200 ml of blood. Such heart-worker will have time to fill a bath with blood for any four minutes!

without knowing weariness

The Cardiac muscle on which share the heart great bulk is necessary, is not similar to other muscles of an organism. It is called as a myocardium and works tirelessly, unlike muscles of fingers and a palm which will quickly get tired of regular reductions and relaxations. On the average, for all time of human life the myocardium is reduced more than 2,5 billion times.

Frequency and filling of warm reductions are regulated by two main mechanisms. One is central nervous system, including a wandering nerve. It works automatically, forcing heart to be reduced in the necessary rhythm even during a dream. One group of nerves accelerates palpitation, and another slows down it, operating as a brake.

Other mechanism are hormones, the special substances developed by an organism and transferred by blood. So, a hormone adrenaline forces heart to fight more often, raising the general readiness of an organism for action.

The Myocardium differs from other muscles also that continues to be reduced in itself even without the nervous or hormonal control about 150 times a minute. In a wall of the right auricle there is the special site named the driver of a rhythm. It publishes the weak electric impulses extending on all cardiac muscle. Passing on nervous fibres, they force to be reduced a cardiac muscle. In case of failure of the natural driver of a rhythm, or "Іыхъ=ЁюяЁютюфъш" to the patient can vshit electronic kardiostimuljator, connected to heart by the most thin conductings and forcing it to be reduced in a due rhythm.

When heart plays pranks

Sometimes we feel that about heart fights "ъръ-=ю not =ръ". It starts to beat without restraint from strong affliction, excitement or fear, but can "т№ёъръштр=і from a breast and with happiness, amazement or great love. It occurs because by order of nerves or hormones heart gets off from a habitual rhythm, changing rate and force of blows. The given deviations are usual reaction of an organism on external razdrazhiteli.

Today we know that all these processes co-ordinates and supervises a brain. However before people have understood it, was considered that such emotions as love, the happiness and grief, arise in heart. About the cruel man say that at it "ърьхээюх ёхЁфчх"; about the devoted friend -"тхЁэюх ёхЁфчх"; the person brave allocate "ыітшэ№ь ёхЁфчхь". Loss of love is at the bottom "Ёрчсш=юую ёхЁфчр" cure which only new love can. Happy people were and remain "ьюыюф№ьш ёхЁфчхь". However scientific researches far from romanticism have shown that heart is only the pump reacting to requirements of an organism, and actually all the brain operates.

Smooth sliding

Our tireless heart with each blow that increases, decreases in size. However from these movements do not wear out neither the next lungs, nor blood vessels. They invariably remain smooth and slippery for heart is hidden in a damp bag, or a pericardium, allowing it is easy to it to slide at each expansion and reduction.

The Internal cavity of heart also is protected from influence of blood circulating under a high pressure by the person vystilkoj, named endokardom.

As well as any other part of a body, heart requires own blood supply, bringing to its muscles oxygen, energy and nutrients. Strangely enough, heart cannot take advantage of that blood which it pumps over. The reason partly that blood in heart is under very high pressure. For blood delivery to all fabrics of a cardiac muscle small blood vessels (capillaries), and so a high pressure them simply are necessary would break off. Besides the blood which is passing through right zheludochek, is very poor oxygen and goes for enrichment to lungs.

Therefore heart has own blood vessels - two coronary arteries. They branch off from the main artery, or an aorta, hardly above a place of its connection with heart. As well as all other arteries, coronary vessels branch on a heart surface, forming a dense network.

we Will take care of the main pump

The Majority of bodies of a body use no more than 1/4 oxygen brought by blood. But heart uses 3/4 oxygen, arriving of coronary arteries. From this it is visible, as assiduously it works, without stopping for a second from the first till last day lives and as its safety factor is insignificant.

Therefore in our interests in time to take care of the precious pump - to eat healthy food, regularly to be engaged in gymnastics, to abstain from smoking and alcohol.