Cardiac cycle briefly
The heart beats rhythmically and cyclically. One cycle lasts 0.8-0.85 seconds, which is approximately 72-75 contractions (beats) per minute.
Main phases:
Diastole - relaxation of the heart muscle (myocardium). In this case, there is an increase in the own blood supply to the myocardium and metabolic processes in it. During diastole, the cavities of the heart are filled with blood: simultaneously both the atria and the ventricles. It is important to note that blood fills simultaneously and atria, and ventricles, because valves between the atria and ventricles (atrioventricular) are open in diastole.
Complete cardiac cycle
Systole - contraction of the muscle layer (myocardium) and the release of blood from the heart cavities. First, the ears of the heart contract, then the atria and after them the ventricles. The contraction runs through the heart in a wave from the ears to the ventricles. The contraction of the heart muscle is triggered by its excitation, and excitation starts from the sinoatrial node in the upper part of the atria.
From the point of view of the movement of excitation through the heart muscle, the cycle should begin with excitation and contraction of the atria, because. it is on them that the excitation from the main pacemaker of the heart goes - sino-atrial node.
pacemaker
Driver heart rate - This is a special section of the heart muscle, which independently generates electrochemical impulses that excite the heart muscle and lead to its contraction.
In humans, the leading pacemaker is sinoatrial (sinoatrial) node. This is a section of the heart tissue containing "pacemaker" cells , i.e. cells capable of spontaneous excitation. It is located on the arch of the right atrium at the confluence of the superior vena cava into it. The node consists of a small number of heart muscle fibers, innervated by the endings of neurons from the autonomic nervous system. It is important to understand that autonomic innervation does not create an independent rhythm of heart impulses, but only regulates (changes) the rhythm that is set by the pacemaker heart cells themselves. In the sinoatrial node, each wave of excitation of the heart is born, which leads to a contraction of the heart muscle and serves as a stimulus for the emergence of the next wave.
Phases of the cardiac cycle
So, the wave of contraction of the heart provoked by a wave of excitation begins with the atria.
1. Systole (contraction) of the atria (together with ears) - 0.1 s . The atria contract and push the blood already in them into the ventricles. The ventricles also already have blood that has been poured into them from the veins during diastole, passing through the atria and open atrioventricular valves. Due to their contraction, the atria pump additional portions of blood into the ventricles.
2. Diastole (relaxation) of the atria - this is the relaxation of the atria after contraction, it lasts 0,7 seconds. Thus, the resting time of the atria far exceeds the time of their work, and this is important to know. From the ventricles, blood cannot return back to the atria due to special atrioventricular valves between the atria and ventricles (tricuspid on the right and bicuspid, or mitral, on the left). Thus, in diastole, the walls of the atria are relaxed, but blood does not flow into them from the ventricles. During this period, the heart has 2 empty and 2 filled chambers. Blood from the veins begins to flow into the atria. At first, blood slowly fills the relaxed atria. Then, after the contraction of the ventricles and the relaxation that has come in them, it opens the valves with its pressure and enters the ventricles. The atrial diastole has not yet ended.
And finally, a new wave of excitation is born in the sino-atrial node and, under its influence, the atria pass to systole and push the blood accumulated in them into the ventricles.
3. Ventricular systole – 0.3 s . The wave of excitation comes from the atria, as well as along the interventricular septum, and reaches the ventricular myocardium. The stomachs contract. Blood under pressure is ejected from the ventricles into the arteries. From the left - to the aorta to run along big circle circulation, and from the right to the pulmonary trunk to run through the pulmonary circulation. Maximum force and maximum pressure blood is supplied by the left ventricle. It has the most powerful myocardium of all the chambers of the heart.
4. Ventricular diastole - 0.5 s . Note that again rest is longer than work (0.5s vs 0.3s). The ventricles have relaxed, the semilunar valves on their border with the arteries are closed, they do not allow blood to return to the ventricles. Atrioventricular (atrioventricular) valves are open at this time. The filling of the ventricles with blood begins, which enters them from the atria, but so far without atrial contraction. All 4 chambers of the heart, i.e. ventricles and atria are relaxed.
5. Total diastole of the heart 0.4 s . The walls of the atria and ventricles are relaxed. The ventricles are filled with blood flowing into them through the atria from the vena cava, 2/3, and the atria - completely.
6. New cycle . The next cycle begins atrial systole .
Video:Pumping blood to the heart
To consolidate this information, look at the animated diagram of the cardiac cycle:
Animated diagram of the cardiac cycle - I strongly advise you to click and view the details!
Details of the work of the ventricles of the heart
1. Systole.
2. Exile.
3. Diastole
Ventricular systole
1. Systole period , i.e. reduction, consists of two phases:
1) Asynchronous reduction phase – 0.04 s . There is an uneven contraction of the wall of the ventricles. At the same time, there is a contraction of the interventricular septum. Due to this, pressure builds up in the ventricles, and as a result, the atrioventricular valve closes. As a result, the ventricles are isolated from the atria.
2) Isometric contraction phase . This means that the length of the muscles does not change, although their tension increases. The volume of the ventricles also does not change. All valves are closed, the walls of the ventricles contract and tend to shrink. As a result, the walls of the ventricles tense up, but the blood does not move. But at the same time, blood pressure inside the ventricles increases, it opens the semilunar valves of the arteries and an outlet appears for the blood.
2. Period of expulsion of blood – 0.25 s
1) Rapid ejection phase - 0.12 s.
2) Slow ejection phase - 0.13 s.
Ejection (ejection) of blood from the heart
Pressurized blood is forced out of the left ventricle into the aorta. The pressure in the aorta rises sharply, and it expands, taking a large portion of blood. However, due to the elasticity of its wall, the aorta immediately contracts again and drives blood through the arteries. The expansion and contraction of the aorta generates a transverse wave, which propagates at a certain speed through the vessels. This is a wave of expansion and contraction of the walls of blood vessels - a pulse wave. Its speed does not match the speed of blood flow.
Pulse - This is a transverse wave of expansion and contraction of the arterial wall, generated by the expansion and contraction of the aorta when blood is ejected into it from the left ventricle of the heart.
Ventricular diastole
Proto-diastolic period – 0.04 s. From end of ventricular systole to closure semilunar valves. During this period, part of the blood returns to the ventricle from the arteries under the pressure of the blood in the circulatory circles.
Isometric relaxation phase – 0.25 s. All valves are closed, muscle fibers are contracted, they have not yet stretched. But their tension is decreasing. The pressure in the atria becomes higher than in the ventricles, and this blood pressure opens the atrioventricular valves to pass blood from the atria to the ventricles.
Filling phase . There is a general diastole of the heart, in which all its chambers are filled with blood, and at first quickly, and then slowly. Blood transits through the atria and fills the ventricles. The ventricles are filled with blood to 2/3 of the volume. At this moment, the heart is functionally 2-chambered, because only its left and right halves are separated. Anatomically, all 4 chambers are preserved.
presystole . The ventricles are finally filled with blood as a result of atrial systole. The ventricles are still relaxed, while the atria are already contracting.
systole ventricles are usually divided into two periods - the period of tension and the period of expulsion of blood, and diastole- for three periods - the proto-diastolic period, the isometric relaxation period and the filling period.
The systole-diastole cycle of the ventricles is presented in the following form.
- Ventricular systole - 0.33 s.
- Voltage period - 0.08 s: asynchronous reduction phase - 0.05 s; isometric contraction phase - 0.03 s.
- The period of expulsion of blood - 0.25 s: the phase of rapid expulsion - 0.12 s; slow ejection phase - 0.13 s.
- Ventricular diastole - 0.47 s.
- Protodiastolic period - 0.04 s.
- Isometric relaxation period - 0.08 s. The period of filling with blood is 0.35 s; the phase of rapid filling is 0.08 s; slow filling phase - 0.26 s; the filling phase due to atrial systole is 0.1 s.
- Ventricular systole takes 0.33 s.
Ventricular systole
During the period of stress, the pressure inside the ventricles rises, the atrioventricular valves close. This happens when the pressure in the ventricles becomes slightly higher than in the atria. The time interval from the onset of excitation and contraction of ventricular cardiomyocytes to the closing of the atrioventricular valves is called the phase of asynchronous contraction. In the remaining 0.03 s, rapid rise intraventricular pressure: the blood is in a closed space - the atrioventricular valves are closed, and the semilunar valves are not yet open. Due to the incompressibility of blood and the inflexibility of the walls of the ventricles, as a result of the continued contraction of myocardiocytes, pressure increases in the cavities of the ventricles of the heart. This is the isometric contraction phase, at the end of which the semilunar valves open. In the left ventricle, this occurs when the pressure reaches 75-85 mm Hg, i.e. such pressure, which is slightly higher than in the aorta during diastole, and in the right ventricle - 15-20 mm Hg, i.e. slightly higher than in the pulmonary trunk. The opening of the semilunar valves allows the expulsion of blood into the aorta and pulmonary trunk. During the rest of the ventricular systole - 0.25 s - blood is expelled. At the beginning, the process of expulsion occurs quickly - the pressure in the vessels leaving the ventricles (aorta, pulmonary trunk) is relatively small, and in the ventricles it continues to increase: in the left up to 120-130 mm Hg, in the right up to 25-30 mm Hg . The same pressure is created respectively in the aorta and pulmonary trunk. As the aorta and pulmonary trunk are filled with blood leaving the ventricles, the resistance to the outgoing blood flow increases and the fast ejection phase is replaced by a slow ejection phase.
Ventricular diastole
Diastole ventricles takes about 0.47 s. It starts from the period of protodiastole: this is the period of time from the beginning of the decrease in pressure inside the ventricles until the closing of the semilunar valves, i.e. until the pressure in the ventricles becomes less than the pressure in the aorta and pulmonary trunk. This period lasts about 0.04 s. The pressure in the ventricles in the next 0.08 s continues to fall very rapidly. As soon as it drops to almost zero, the atrioventricular valves open and the ventricles fill with blood that has accumulated in the atria. The time from the closing of the semilunar valves to the opening of the atrioventricular valves is called the isometric relaxation period.
The period of filling the ventricles with blood lasts 0.35 s. It begins from the moment the atrioventricular valves open: all the blood (about 33 ml) rushes into the ventricles during the rapid filling phase. Then comes the phase of slow passive filling, or the phase of diastasis, - 0.26 s; during this period, all the blood that enters the atria flows in "transit" immediately from the veins through the atrium into the ventricles.
Atrial systole
At the end, atrial systole sets in, which “squeezes out” an additional 40 ml of blood into the ventricles in 0.1 s. This phase is called presystolic. So, the duration of atrial systole is 0.1 s, the duration of diastole is 0.7 s, in the ventricles, respectively, 0.33 and 0.47 s. These figures indicate that 40% of the time ventricular myocardiocytes are in an active state and 60% are “resting”. With an increase in cardiac activity, for example, during muscular work, with emotional stress, the duration of the cardiac cycle is shortened, primarily due to a reduction in the time of the general pause. A further increase in the load leads to a shortening of the duration of systole.
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Systole and diastole. Ventricular systole
Table of contents for the topic "Excitability of the heart muscle. Cardiac cycle and its phase structure. Heart sounds. Innervation of the heart.":1. Excitability of the heart muscle. Myocardial action potential. Myocardial contraction.
2. Excitation of the myocardium. Myocardial contraction. Conjugation of excitation and contraction of the myocardium.
4. Diastolic period of the ventricles of the heart. Relaxation period. Filling period. Heart preload. Frank-Starling law.
5. Activity of the heart. Cardiogram. Mechanocardiogram. Electrocardiogram (ECG). Electrodes ecg.
6. Heart sounds. First (systolic) heart sound. Second (diastolic) heart sound. Phonocardiogram.
7. Sphygmography. Phlebography. Anacrota. Catacrot. Phlebogram.
8. Cardiac output. regulation of the cardiac cycle. Myogenic mechanisms of regulation of the activity of the heart. The Frank-Starling effect.
9. Innervation of the heart. chronotropic effect. dromotropic effect. inotropic effect. bathmotropic effect.
10. Parasympathetic effects on the heart. Influence on the heart of the vagus nerve. Vagal effects on the heart.
The work of the heart represents a continuous alternation of periods of contraction ( systole) and relaxation ( diastole). Replacing each other systole and diastole constitute cardiac cycle. Since at rest the heart rate is 60-80 cycles per minute, each of them lasts about 0.8 s. At the same time, 0.1 s is occupied by atrial systole, 0.3 s by ventricular systole, and the rest of the time by total diastole of the heart.
To beginning of systole myocardium relaxed, and the heart chambers are filled with blood coming from the veins. Atrioventricular valves at this time are open and the pressure in the atria and ventricles is almost the same. The generation of excitation in the sinoatrial node leads to atrial systole, during which, due to the pressure difference, the end-diastolic volume of the ventricles increases by approximately 15%. With the end of atrial systole, the pressure in them decreases.
Rice. 9.11. Changes in left ventricular volume and pressure fluctuations in the left atrium, left ventricle and aorta during the cardiac cycle. I - beginning of atrial systole; II - the beginning of ventricular systole; III - the moment of opening of the semilunar valves; IV - the end of the systole of the ventricles and the moment of closing of the semilunar valves; V - disclosure of atrioventricular valves. The lowering of the line showing the volume of the ventricles corresponds to the dynamics of their emptying.Since the valves between the main veins and the atria are absent, during atrial systole there is a contraction of the annular muscles surrounding the mouths of the hollow and pulmonary veins, which prevents the outflow of blood from the atria back into the veins. At the same time, atrial systole is accompanied by some increase in pressure in the vena cava. Of great importance is the provision of a turbulent nature of the flow of blood from the atria to the ventricles, which contributes to the slamming of the atrioventricular valves. The maximum and average pressure in the left atrium during systole are 8-15 and 5-7 mm Hg, respectively. Art., in the right atrium - 3-8 and 2-4 mm Hg. Art. (Fig. 9.11).
With transition excitation to the atrioventricular node and the conducting system of the ventricles, the systole of the latter begins. Its initial stage stress period) lasts 0.08 s and consists of two phases. Asynchronous reduction phase(0.05 s) is the process of spreading excitation and contraction through the myocardium. The pressure in the ventricles remains virtually unchanged. In the process of the beginning synchronous contraction of the myocardium of the ventricles, when the pressure in them increases to a value sufficient to close the atrioventricular valves, but insufficient to open the semilunar valves, the phase of isovolumic, or isometric, contraction begins.
Further increase in pressure causes the semilunar valves to open and period of exile blood from the heart, the total duration of which is 0.25 s. This period consists of rapid ejection phases(0.13 s), during which the pressure in the ventricles continues to rise and reaches maximum values, and slow ejection phases(0.13 s), during which the pressure in the ventricles begins to decrease, and after the end of the contraction, it drops sharply. In the main arteries, the pressure decreases much more slowly, which ensures the slamming of the semilunar valves and prevents backflow of blood. The period of time from the beginning of relaxation of the ventricles to the closing of the semilunar valves is called the proto-diastolic period.
Term systole means muscle contraction. Allocate electrical systole - electrical activity, which stimulates the myocardium and causes mechanical systole- contraction of the heart muscle and a decrease in the volume of the heart chambers. Term diastole means muscle relaxation. During the cardiac cycle, there is an increase and decrease in blood pressure, respectively. high pressure during ventricular systole is called systolic, and low during their diastole - diastolic.
The frequency of repetition of the cardiac cycle is called the heart rate, it is set by the pacemaker of the heart.
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Periods and phases of the cardiac cycle
A summary table of periods and phases of the cardiac cycle with approximate pressures in the chambers of the heart and the position of the valves is given at the bottom of the page.
Ventricular systole
Ventricular systole- the period of contraction of the ventricles, which allows you to push the blood into the arterial bed.
In the contraction of the ventricles, several periods and phases can be distinguished:
- Voltage period- characterized by the onset of contraction muscle mass ventricles without changing the volume of blood inside them.
- Asynchronous reduction- the beginning of excitation of the ventricular myocardium, when only individual fibers are involved. The pressure change in the ventricles is enough to close the atrioventricular valves at the end of this phase.
- - almost the entire myocardium of the ventricles is involved, but there is no change in the volume of blood inside them, since the efferent (semilunar - aortic and pulmonary) valves are closed. Term isometric contraction not entirely accurate, since at this time there is a change in the shape (remodeling) of the ventricles, tension of the chords.
- Period of exile characterized by the expulsion of blood from the ventricles.
- Rapid Exile- the period from the opening of the semilunar valves to the achievement of systolic pressure in the cavity of the ventricles - during this period maximum amount blood.
- slow exile- the period when the pressure in the cavity of the ventricles begins to decrease, but is still greater than the diastolic pressure. At this time, the blood from the ventricles continues to move under the action of the kinetic energy imparted to it, until the pressure in the cavity of the ventricles and the efferent vessels is equalized.
In a state of calm, the ventricle of the heart of an adult ejects 50-70 ml of blood for each systole (shock, or systolic, volume). The cardiac cycle lasts up to 1 s, respectively, the heart makes from 60 contractions per minute (heart rate, heart rate). It is easy to calculate that even at rest, the heart pumps 4 liters of blood per minute (minute blood volume, IOC). During maximum load The stroke volume of the heart of a trained person can exceed 200 ml, the pulse can exceed 200 beats per minute, and the blood circulation can reach 40 liters per minute.
Diastole
Diastole The period of time during which the heart relaxes to receive blood. In general, it is characterized by a decrease in pressure in the cavity of the ventricles, the closure of the semilunar valves and the opening of the atrioventricular valves with the advancement of blood into the ventricles.
- Ventricular diastole
- Protodiastole- the period of the onset of myocardial relaxation with a pressure drop lower than in the efferent vessels, which leads to the closure of the semilunar valves.
- - similar to the phase of isovolumetric contraction, but exactly the opposite. There is an elongation of muscle fibers, but without changing the volume of the ventricular cavity. The phase ends with the opening of the atrioventricular (mitral and tricuspid) valves.
- Filling period
- Fast filling- the ventricles rapidly restore their shape in a relaxed state, which significantly reduces the pressure in their cavity and sucks blood from the atria.
- Slow filling- the ventricles have almost completely restored their shape, the blood flows already because of the pressure gradient in the vena cava, where it is higher by 2-3 mm Hg. Art.
Atrial systole
It is the final phase of diastole. At normal frequency In cardiac contractions, the contribution of atrial contraction is small (about 8%), since for a relatively long diastole, the blood already has time to fill the ventricles. However, with an increase in the frequency of contractions, the duration of diastole generally decreases and the contribution of atrial systole to ventricular filling becomes very significant.
External manifestations of cardiac activity
The following groups of manifestations are distinguished:
- Electrical- ECG, ventriculocardiography
- Sound- auscultation, phonocardiography
- Mechanical:
- Apex beat - palpation, apexcardiography
- Pulse wave - palpation, sphygmography, phlebography
- Dynamic effects - changing the center of gravity chest in the cardiac cycle - dynamocardiography
- Ballistic effects - shaking of the body at the time of ejection of blood from the heart - ballistocardiography
- Change in size, position and shape - ultrasound, X-ray kymography
| Period | Phase | t, | AV valves | SL valves | P RV, | P LV, | P atrium, | |
|---|---|---|---|---|---|---|---|---|
| 1 | Atrial systole | 0,1 | O | Z | Start ≈0 | Start ≈0 | Start ≈0 | |
| Voltage period | 2 | Asynchronous reduction | 0,05 | O→W | Z | 6-8→9-10 | 6-8→9-10 | 6-8 |
| 3 | Isovolumetric contraction | 0,03 | Z | B→O | 10→16 | 10→81 | 6-8→0 | |
| Period of exile | 4 | Rapid Exile | 0,12 | Z | O | 16→30 | 81→120 | 0→-1 |
| 5 | slow exile | 0,13 | Z | O | 30→16 | 120→81 | ≈0 | |
| Ventricular diastole | 6 | Protodiastole | 0,04 | Z | O→W | 16→14 | 81→79 | 0-+1 |
| 7 | Isovolumetric relaxation | 0,08 | B→O | Z | 14→0 | 79→0 | ≈+1 | |
| Filling period | 8 | Fast filling | 0,09 | O | Z | ≈0 | ≈0 | ≈0 |
| 9 | Slow filling | 0,16 | O | Z | ≈0 | ≈0 | ≈0 | |
| This table is calculated for normal indicators pressure in large (120/80 mm Hg) and small (30/15 mm Hg) circles of blood circulation, cycle duration 0.8 s. Accepted abbreviations: |
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The heart is the main organ human body. His important function is to sustain life. The processes taking place in this organ excite the heart muscle, starting a process in which contractions and relaxation alternate, which is a vital cycle to maintain rhythmic blood circulation.
The work of the heart is essentially a change of cyclic periods and continues without stopping. The viability of the body depends primarily on the quality of the work of the heart.
According to the mechanism of action, the heart can be compared to a pump that pumps blood flows from the veins into the arteries. These features are provided special properties myocardium, such as excitability, the ability to contract, serve as a conductor, work in automatic mode.
A feature of myocardial movement is its continuity and cyclicity due to the presence of a pressure difference at the ends of the vascular system (venous and arterial), one of the indicators of which in the main veins is 0 mm Hg, while in the aorta it can reach up to 140 mm.
Cycle length (systole and diastole)
In order to understand the essence of the cyclic function of the heart, one should understand what is systole and what is diastole. The first is characterized by the release of the heart from the blood fluid, thus. contraction of the heart muscle is called systole, while diastole is accompanied by the filling of the cavities with blood flow.
The process of alternating systole and diastole of the ventricles and atria, as well as the general relaxation that follows, is called the cycle of cardiac activity.
Those. The opening of the leaf valves occurs at the time of systole. When the leaflet contracts during diastole, blood rushes to the heart. The pause period also has great importance, because the flap valves are closed during this rest time.
Table 1. Cycle duration in humans and animals in comparison
The duration of systole is in humans, essentially the same period as diastole, while in animals this period lasts somewhat longer.
Duration different phases cycle of the heart is determined by the frequency of contractions. Their increase affects the length of all phases, to a greater extent, this applies to diastole, which becomes noticeably smaller. At rest healthy organisms have a heart rate of up to 70 cycles per minute. At the same time, they can have a duration of up to 0.8 s.
Before contractions, the myocardium is relaxed, its chambers are filled with blood fluid from the veins. The difference of this period is the full opening of the valves, and the pressure in the chambers - in the atria and ventricles remains at the same level. The myocardial excitation impulse originates from the atria.
Then it provokes an increase in pressure and, due to the difference, the blood flow is gradually pushed out.
The cyclical work of the heart is distinguished by a unique physiology, because. it independently provides itself with an impulse for muscle activity, through the accumulation of electrical stimulation.
Phase structure with table
To analyze changes in the heart, you also need to know what phases this process consists of. There are such phases as: contraction, expulsion, relaxation, filling. What are the periods, sequence and place in the cycle of the heart certain types each of them can be seen in Table 2.
Table 2. Cardiac cycle indicators
| Systole in the atria | 0.1 s | |
|---|---|---|
| Periods | Phases | |
| Systole in the ventricles 0.33 s | voltage - 0.08 s | asynchronous reduction - 0.05 s |
| isometric contraction - 0.03 s | ||
| expulsion 0.25 s | fast ejection - 0.12 s | |
| slow ejection - 0.13 s | ||
| Ventricular diastole 0.47 s | relaxation - 0.12 s | Protodiastolic interval - 0.04 s |
| isometric relaxation - 0.08 s | ||
| filling - 0.25 s | quick filling - 0.08 s | |
| slow filling - 0.17 s |
K ardiocycle is divided into several phases with a specific purpose and duration, ensuring the correct direction blood flow in order precisely established by nature.
Cycle phase names:
Video: Cardiac cycle
Heart sounds
The activity of the heart is characterized by emitted cyclic sounds, they resemble tapping. The components of each beat are two easily distinguishable tones.
One of them arises from contractions in the ventricles, the impulse of which arises from the slamming valves that close the atrioventricular orifices during myocardial tension, preventing the blood flow from penetrating back into the atria.
The sound at this time appears directly when the free edges are closed. The same blow is produced with the participation of the myocardium, the walls of the pulmonary trunk and aorta, tendon filaments.
The next tone occurs during diastole from the movement of the ventricles, being at the same time a consequence of the activity of the semilunar valves, which prevent the blood flow from penetrating back, acting as a barrier. The knock becomes audible at the moment of connection in the lumen of the edges of the vessels.
In addition to the two most prominent tones in the cycle of the heart, there are two more, called the third and fourth. If a phonendoscope is enough to hear the first two, then the rest can be registered only with a special device.
Listening to heart beats is extremely important for diagnosing his condition and possible changes, allowing to judge the development of pathologies. Some ailments of this organ are characterized by a violation of the cycle, bifurcation of beats, a change in their volume, accompanied by additional tones or other sounds, including squeaks, clicks, noises.
Video: Auscultation of the heart. Basic tones
Cardiac cycle- a unique physiological reaction of the body created by nature, necessary to maintain its vital activity. This cycle has certain patterns, which include periods of muscle contraction and relaxation.
According to the results of the phase analysis of the activity of the heart, it can be concluded that its two main cycles are intervals of activity and rest, i.e. between systole and diastole, essentially about the same.
An important indicator of the health of the human body, determined by the activity of the heart, is the nature of its sounds, in particular, noises, clicks, etc. should cause a wary attitude.
In order to avoid the development of pathologies in the heart, it is necessary to timely undergo diagnostics in medical institution, where the specialist will be able to assess changes in the cardiac cycle according to its objective and accurate indicators.
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