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It's called the heart muscle. The value of biochemical processes in the myocardium. Pain as a sign of diseases of the cardiovascular system

Myocardium, i.e. cardiac muscle is the muscular tissue of the heart, which makes up the bulk of its mass. Measured, coordinated contractions of the atrial and ventricular myocardium are guaranteed by the conduction system of the heart.

It should be noted that the heart represents two separate pumps: the right half of the heart, i.e. the right heart, pumping blood through the lungs, and the left half of the heart, i.e. the left heart pumps blood through the peripheral organs. In turn, the two pumps consist of two pulsating chambers: the ventricle and the atrium. The atrium is a less weak pump and pushes blood into the ventricle. The most important role of the "pump" is played by the ventricles, thanks to them, blood from the right ventricle enters the pulmonary (small) circulation, and from the left - into the systemic (large) circulation.

The structure of the heart muscle

The heart consists of 3 main types of muscle tissue: ventricular myocardium, atrial myocardium, and atypical myocardium of the cardiac conduction system. The heart muscle has a mesh structure, which is formed from muscle fibers. The mesh structure is achieved through the development of bonds between the fibers. Connections are established through lateral bridges, so that the entire network is a narrow-looped syncytium.

Loose connective tissue is located between the muscle fibers of the myocardium. Also, muscle fibers are wrapped around a dense network of blood capillaries.

Dystrophy of the heart muscle

Myocardial dystrophy is a violation of the heart muscle of non-inflammatory passage. It is worth noting that the change in the heart occurs gradually. Any changes can be detected on the ECG. Subsequently, an increase in the size of the heart (a sign of heart failure) is noted. Also, with myocardial dystrophy, rhythm disturbance is observed (atrial fibrillation, extrasystole).

Cardiac muscle dystrophy occurs in many diseases, namely: hypertension, anemia, pathology of the liver, kidneys, dysproteinemia, etc.

With myocardial dystrophy, people experience pain in the region of the heart of any nature that is not associated with physical exertion.

All pain in the chest area is accompanied by a spasm of the heart muscle. As a result, blood does not enter the heart muscle. If this continues for more than 40 minutes, then the heart muscle may die. A person has a myocardial infarction.

Heart spasm can trigger a heart attack. As a rule, the cause is an atherosclerotic plaque that partially covers the artery, and spasm of the artery can cover it completely. At this point, the heart muscle experiences an acute lack of oxygen (ischemia). Initially, it is necessary to remove the spasm of the vessel, i.e. open a vessel for blood flow.

It is important to note that rupture of the heart muscle accounts for 40% of many cases of sudden clinical death. Myocardial rupture in women occurs twice as often as in men. Also, rupture of the heart muscle is observed more often in a primary infarction than in a secondary one. The main age of patients is 60 years and older.
In turn, an increase in the heart muscle entails an excessive effort of the heart to prevent the abnormal reverse flow of blood, as well as the need to expel the blood trapped in the heart and make the blood flow correct. With increased exercise, the heart becomes stronger and thicker.

It should be noted that temporarily an increase in the heart occurs with inflammation of the heart, and permanently with a defect in the heart valves or with the degeneration of muscle tissue.

Depletion of the heart muscle occurs due to a violation of cellular energy nutrition. Since the cells of the heart need daily and complete nutrition. The most common cause of heart failure is stress. Also important is the lack of water in the body, which entails thickening of the blood and increased stress on the heart muscle. This is where a number of problems arise.
Strengthening and restoring the heart muscle is the most important and difficult task. Its value is human life.
Symptoms of myocardial muscle problems:

heartbeat;
dyspnea;
fast fatiguability;
chest pain.

Programs for the restoration of the heart muscle are preventive, restorative and restorative.

Vitamins for the heart muscle

First of all, the “problem” heart needs vitamins and microelements with an antioxidant effect.
The most important vitamins:

vitamin C - strengthens the walls of blood vessels, helps to overcome stress and reduces cholesterol in the blood;
vitamin E - contributes to the regulation of contraction of the heart muscle;
vitamin F - contributes to the destruction of saturated fats, which are responsible for the formation of sclerotic plaques;
vitamin B6 - relieves spasms of blood vessels and normalizes the blood supply to the heart.

Drugs that strengthen the heart muscle:

Asparkam is a complex preparation based on magnesium and potassium. The main indication for use is the restoration of electrolyte balance in the heart muscle.
Riboxin - normalizes the heart rhythm, strengthens the myocardium and improves the blood supply to the coronary vessels.
Rhodiola rosea is a herbal adaptogen that improves the contractility of the heart muscle.

All existing drugs for the heart muscle are recommended to be taken only as directed by a doctor.

The heart is rightfully the most important human organ, because it pumps blood and is responsible for the circulation of dissolved oxygen and other nutrients throughout the body. Stopping it for a few minutes can cause irreversible processes, dystrophy and death of organs. For the same reason, diseases and cardiac arrest are one of the most common causes of death.

What tissue forms the heart

The heart is a hollow organ about the size of a human fist. It is almost completely formed by muscle tissue, so many doubt: is the heart a muscle or an organ? The correct answer to this question is an organ formed by muscle tissue.

The heart muscle is called the myocardium, its structure differs significantly from the rest of the muscle tissue: it is formed by cardiomyocyte cells. Cardiac muscle tissue has a striated structure. It contains thin and thick fibers. Microfibrils are clusters of cells that form muscle fibers, collected in bundles of different lengths.

Properties of the heart muscle - ensuring the contraction of the heart and pumping blood.

Where is the heart muscle located? In the middle, between two thin shells:

epicardium;
Endocardium.

The myocardium accounts for the maximum amount of heart mass.

Mechanisms that provide reduction:

There are two phases in the heart cycle:

Relative, in which cells respond to strong stimuli;
Absolute - when for a certain period of time the muscle tissue does not respond even to very strong stimuli.

Compensation mechanisms

The neuroendocrine system protects the heart muscle from overload and helps maintain health. It provides the transmission of "commands" to the myocardium when it is necessary to increase the heart rate.

The reason for this may be:

A certain state of internal organs;
Reaction to environmental conditions;
Irritants, including nervous.

Usually in these situations, adrenaline and norepinephrine are produced in large quantities, in order to "balance" their action, an increase in the amount of oxygen is required. The faster the heart rate, the more oxygenated blood is carried throughout the body.

Features of the structure of the heart

The heart of an adult weighs approximately 250-330 g. In women, the size of this organ is smaller, as is the volume of pumped blood.

It consists of 4 chambers:

two atria;
Two ventricles.

The pulmonary circulation often passes through the right heart, and the large circle passes through the left. Therefore, the walls of the left ventricle are usually larger: so that in one contraction the heart can push out a larger volume of blood.

The direction and volume of the ejected blood is controlled by the valves:

Bicuspid (mitral) - on the left side, between the left ventricle and the atrium;
Three-leaved - on the right side;
Aortic;
Pulmonary.

Pathological processes in the heart muscle

With small malfunctions in the work of the heart, a compensatory mechanism is activated. But conditions are not uncommon when pathology develops, dystrophy of the heart muscle.

This leads to:

oxygen starvation;
Loss of muscle energy and a number of other factors.

Muscle fibers become thinner, and the lack of volume is replaced by fibrous tissue. Dystrophy usually occurs "in conjunction" with beriberi, intoxication, anemia, and disruption of the endocrine system.

The most common causes of this condition are:

Myocarditis (inflammation of the heart muscle);
atherosclerosis of the aorta;
Increased blood pressure.

If it hurts heart: the most common diseases

There are quite a lot of heart diseases, and they are not always accompanied by pain in this particular organ.

Often in this area pain sensations that occur in other organs are given:

Stomach
Lungs;
With chest trauma.

Causes and nature of pain

Pain in the region of the heart is:

sharp penetrating when it hurts even to breathe. They indicate an acute heart attack, heart attack and other dangerous conditions.
Aching occurs as a reaction to stress, with hypertension, chronic diseases of the cardiovascular system.
Spasm, which gives into the hand or shoulder blade.

Often heart pain is associated with:

Emotional experiences.

But often occurs at rest.

All pain in this area can be divided into two main groups:

Anginal or ischemic- associated with insufficient blood supply to the myocardium. Often occur at the peak of emotional experiences, also in some chronic diseases of angina pectoris, hypertension. It is characterized by a sensation of squeezing or burning of varying intensity, often radiating to the hand.
Cardiac disturb the patient almost constantly. They have a weak whining character. But the pain can become sharp with a deep breath or physical exertion.

The heart is located in the chest cavity as part of the mediastinal organs, displaced to the left. The position and mass of the heart depend on the type of physique, shape of the chest, sex and age of the person. In women, on average, the mass of the heart is less (250 g) than in men (300 g). In athletes and people engaged in physical labor, the size of the heart is larger than in people who are not associated with great physical exertion.

The heart is a hollow muscular organ divided internally into four cavities: the right and left atria, and the right and left ventricles. The wall of the heart consists of three layers: the inner endothelial layer with valves - the endocardium, the middle muscle layer - the myocardium and the outer connective tissue, covered with a single-layer epithelium - the epicardium. Outside, the heart is covered with a pericardial sac - the pericardium. The cavity between the epicardium and the pericardium contains a small amount of serous fluid, which reduces friction during heart contractions. In the left half of the heart, between the atrium and the ventricle, there is a bicuspid (mitral) valve, in the right half - a tricuspid valve. There are semilunar valves at the mouth of the aorta that prevent blood from returning to the ventricle. The middle layer of the heart wall (myocardium) is made up of muscle cells. cardiomyocytes. In the atria, the myocardium is thinner, in the ventricles it is thicker (especially in the left ventricle). The myocardium in structure belongs to the striated muscles, but has a number of features. Cardiomyocytes are tightly connected to each other, forming a functionally single tissue - syncytium, due to which rapid conduction of excitation and simultaneous contraction of the whole heart is carried out. Carrying out excitation in the myocardium to all working cardiomyocytes performs conducting system heart, which is formed by atypical muscle cells.

Thanks to these cells, the myocardium has specific properties:

1) automation– the ability of atypical muscle cells

conductive system to generate pulses without any external influences;

2) conductivity- the ability of the conductive system to transfer excitation;

3) excitability - the ability of heart muscle cells to be excited under the influence of impulses that come through the conduction system of the heart;

4) contractility - the ability to contract under the influence of these impulses.

Impulses arise in the so-called pacemaker (pacemaker), which is located in the right atrium at the mouth of the vena cava - sinoatrial node or first order node. It generates pulses at a frequency of 60 - 80 beats per minute (60 - 80 pulses / min). Second order knot located in the atrioventricular septum atrioventricular node. The speed of excitation conduction from the node of the first order to the node of the second order is 1 m / s, however, in the node of the second order, the speed of conduction drops to 0.02 - 0.05 m / s, resulting in the formation of an interval between atrial contractions and ventricular contractions. Starts from the node of the second order bundle of His, dividing into right and left legs, which further break up into Purkinje fibers in direct contact with myocardial fibers. In the bundle of His, the conduction velocity reaches 5 m/s, and then in the Purkinje fibers, the conduction velocity again decreases to 1 m/s. Legs of the bundle of His can generate contractions with a frequency of 30 - 40 imp/min. Individual Purkinje fibers can generate impulses at a frequency of 20 beats per minute. The decrease in the ability to automatic, starting from the base of the heart to the top, is the so-called decreasing gradient of automation.

Features of excitability and contractility of the heart muscle.

An important feature of the excitability of the heart muscle is the presence of a long refractory period, i.e. a period of decreased sensitivity to excitation, longer than in other striated muscles. The frequency of generation of excitation by the cells of the conduction system and, accordingly, myocardial contractions is determined by the duration of the refractory phase that occurs after each systole and is about 0.3 s in the heart. A long refractory period is of great biological importance for the heart, since it protects the myocardium from too frequent re-excitation and contraction. The heart muscle contracts according to the all-or-nothing law, since it has close contacts between individual muscle cells - the so-called nexus, or areas of close contact (a common part of the membranes), as a result of which excitation goes unhindered from one cell to another. The myocardium is a functionally unified system, so excitation quickly covers the entire muscle and there is a simultaneous contraction of all muscle cells of the ventricles. The work of the heart is directly dependent on oxygen consumption. Delivery of oxygen to the tissues of the heart is carried out through the coronary arteries, which depart from the aorta. During ventricular systole, the valves close the orifices of the coronary arteries, preventing blood from reaching the heart. When the ventricles relax, the sinuses fill with blood, and the valves block its path back to the left ventricle, at the same time the mouths of the coronary arteries open and blood enters the heart. Since the heart needs a continuous supply of sufficiently large amounts of oxygen to the cells, the blockage of the coronary arteries leads to severe disruption of the heart and the rapid development of necrosis foci (myocardial infarction). Having given up oxygen, the venous blood in the wall of the heart is collected in the anterior cardiac veins and the venous sinus, which open into the cavity of the right and left atria.

The amount of blood flow in the vessels of the ventricles during their systole decreases, therefore, the flow of blood, the delivery of oxygen and nutrients to the myocardium is mainly provided during the period of diastole. The heart rate increases mainly due to the reduction of diastole, therefore, with an increase in heart rate, the supply of oxygen to the myocardium decreases.

Muscle of life or myocardium

The beating of the heart, its contraction, becomes possible thanks to the middle one, which is called the myocardium or heart muscle. Recall that the human motor consists of three layers: the outer or cardiac sac (pericardium), which lines all the cavities of the heart, the inner (endocardium), and the middle one, which directly provides contraction and shocks - the myocardium. Agree, there is no more important muscle in the body. Therefore, the myocardium can rightly be called the muscle of life.

All departments of the human "motor": atria, right and left ventricles have myocardium in their structure. If we imagine the wall of the heart in a section, then the cardiac muscle occupies a percentage of 75 to 90% of the entire thickness of the wall. Normally, the thickness of the muscle tissue of the right ventricle is from 3.5 to 6.3 mm, the left ventricle is 11-14 mm, and the atria is 1.8-3 mm. The left ventricle is the most "inflated" in relation to other parts of the heart, since it is he who carries out the main work of expelling blood into the vessels.

2 Composition and structure

The heart muscle consists of fibers that have a striated striation. The fibers themselves, upon closer examination, consist of special cells, which are called cardiomyocytes. These are special, unique cells. They contain one nucleus, often located in the center, many mitochondria and other organelles, as well as myofibrils - contractile elements, due to which contraction occurs. These structures resemble filaments, not homogeneous, but composed of thinner actin filaments and thicker myosin filaments.

The alternation of thicker and thinner threads makes it possible to observe striation in a light microscope. A section of myofibril, 2.5 microns in size, containing such a striation is called a sarcomere. It is he who is the elementary contractile unit of the myocardial cell. Sarcomeres are the bricks that make up a huge building - the myocardium. Myocardial cells are a kind of symbiosis of smooth muscle tissue and skeletal tissue.

The resemblance to the musculature of the skeleton ensures the striation of the myocardium and the mechanism of contraction, and from the smooth cardiomyocytes they “took” involuntariness, lack of control over consciousness and the presence in the structure of the cell of one nucleus, which has the ability to change shape and size, thus adapting to contractions. Cardiomyocytes are extremely "friendly" - they seem to hold hands: each cell fits snugly to each other, and between the cell membranes there is a special bridge - an intercalary disk.

Thus, all cardiac structures are closely interconnected with each other and form a single mechanism, a single network. This unity is very important: it allows excitation to spread extremely quickly from one cell to the next, and also to transmit a signal to other cells. Thanks to these structural features, in 0.4 seconds, the transfer of excitation and the response of the heart muscle in the form of its contraction becomes possible.

The heart muscle is not only cells of a contractile nature, it is also cells that have a unique ability to generate excitation, cells that conduct this excitation, blood vessels, elements of connective tissue. The middle shell of the heart has a complex structure and organization, which together play a crucial role in the operation of our motor.

3 Structural features of the muscles of the upper heart chambers

The upper chambers or atria have a smaller thickness of the heart muscle compared to the lower ones. The myocardium of the upper "floors" of a complex "building" - the heart, has 2 layers. The outer layer is common to both atria, its fibers run horizontally and envelop two chambers at once. The inner layer includes longitudinally arranged fibers, they are already separate for the right and left upper chambers. It should be noted that the muscle tissue of the atria and ventricles is not interconnected, the fibers of these structures are not intertwined, which ensures the possibility of their separate contraction.

4 Features of the structure of the muscles of the lower heart chambers

The lower "floors" of the heart have a more developed myocardium, in which there are as many as three layers. The outer and inner layers are common to both chambers, the outer layer goes obliquely to the apex, forming curls deep into the organ, and the inner layer has a longitudinal orientation. Papillary muscles and trabeculae are elements of the inner layer of the ventricular myocardium. The middle layer is located between the two described above and is formed by fibers, separate for the left and right ventricles, their course is circular or circular. To a greater extent, the interventricular septum is formed from the fibers of the middle layer.

5 IVS or ventricular delimiter

Separates the left ventricle from the right and makes the human “motor” four-chambered, no less important than the heart chambers, the formation is the interventricular septum (IVS). This structure allows the blood of the right and left ventricles not to mix, while maintaining optimal blood circulation. For the most part, in its structure, the IVS consists of myocardial fibers, but its upper section - the membranous part - is represented by fibrous tissue.

Anatomists and physiologists distinguish the following sections of the interventricular septum: input, muscular and output. Already at 20 weeks in the fetus on ultrasound, this anatomical formation can be visualized. Normally, there are no holes in the septum, but if there are any, doctors diagnose a congenital defect - an IVS defect. With defects in this structure, a mixture of blood flowing through the right chambers to the lungs and oxygen-rich blood from the left heart sections occurs.

Because of this, normal blood supply to organs and cells does not occur, heart pathology and other complications develop, which can lead to death. Depending on the size of the hole, defects are distinguished large, medium, small, and defects are also classified by location. Small defects can spontaneously close after birth or in childhood, other defects are dangerous for the development of complications - pulmonary hypertension, circulatory failure, arrhythmias. They require prompt intervention.

6 Functions of the heart muscle

In addition to the most important contractile function, the heart muscle also performs the following:

Automation. In the myocardium there are special cells that are able to generate an impulse on their own, independently of any other organs and systems. These cells are crowded and form special nodes of automatism. The most important node is the sinoatrial node, it ensures the work of the underlying nodes and sets the rhythm and pace of heart contractions.
Conductivity. Normally, in the heart muscle, excitation is carried from the overlying sections to the underlying ones through a special fiber. If the conducting system "jumps", then blockades or other rhythm disturbances occur.
Excitability. This function characterizes the ability of cardiac cells to respond to a source of excitation - an irritant. Representing a single network due to the close connection with each other by intercalary discs, the heart cells instantly catch the stimulus and go into an excited state.

It makes no sense to describe the importance of the contractile function of the cardiac “motor”, its importance is clear even to a child: as long as the human heart beats, life goes on. And this process is impossible if the heart muscle does not work smoothly and clearly. Normally, the upper chambers of the heart contract first, followed by the ventricles. During the contraction of the ventricles, blood is ejected into the most important vessels of the body, and it is the ventricular myocardium that provides the force of expulsion. Atrial contraction is also provided by cardiomyocytes included in the wall of these cardiac sections.

7 Diseases of the main muscle of the body

The main muscle of the heart, alas, is prone to disease. When inflammation of the heart muscle occurs, doctors diagnose myocarditis. Inflammation can be caused by a bacterial or viral infection. If we are talking about non-inflammatory disorders of a predominantly metabolic nature, then myocardial dystrophy may develop. Another medical term for heart muscle disease is cardiomyopathy. The causes of this condition may be different, but cardiomyopathies from alcohol abuse are increasingly common.

Shortness of breath, tachycardia, chest pain, weakness - these symptoms indicate that it is difficult for the heart muscle to cope with its functions and it requires examination. The main examination methods are electrocardiogram, echocardiography, radiography, Holter monitoring, dopplerography, EFI, angiography, CT and MRI. You should not write off auscultation, through which the doctor can suggest one or another pathology of the myocardium. Each method is unique and complements each other.

The main thing is to conduct the necessary examination at the initial stage of the disease, when the heart muscle can still be helped and restore its structure and functions without consequences for human health.

evolutionary development

Prerequisites for the appearance of the heart

For small organisms, there was no problem with the delivery of nutrients and the removal of metabolic products from the body (diffusion rate is sufficient). However, as the size increases, it becomes necessary to meet the ever-increasing needs of the body in the processes of obtaining energy and food and removing the spent. As a result, primitive organisms already have so-called. "hearts" that provide the necessary functions. Further, as for all homologous (similar) organs, there is a decrease in the number of compartments to two (in humans, two for each circle of blood circulation).

chordates

Paleontological findings suggest that the heart first arose in primitive chordates. However, the appearance of a full-fledged organ is noted in fish. The heart here is two-chambered, a valvular apparatus and a heart sac appear.

The heart of all chordates necessarily has a heart bag (pericardium), valvular apparatus. Mollusk hearts can also have valves, have a pericardium, which in gastropods encircles the hindgut. In insects and arthropods, the organs of the circulatory system can be called hearts in the form of peristaltic extensions of the great vessels. In chordates, the heart is an unpaired organ. In mollusks, arthropods and insects, the amount may vary. The concept of the heart does not apply to worms, etc.

The heart of mammals and birds

The heart of mammals and birds is four-chambered. Distinguish (by blood flow): right atrium, right ventricle, left atrium and left ventricle. Between the atria and ventricles are fibromuscular valves - tricuspid on the right, mitral on the left. At the outlet of the ventricles there are connective tissue valves (pulmonary on the right and aortic on the left). From one or two anterior (upper) and posterior (lower) vena cava, blood enters the right atrium, then into the right ventricle, then through the pulmonary circulation, the blood passes through the lungs, where it is enriched with oxygen, enters the left atrium, then into the left ventricle and , further, into the main artery of the body - the aorta (birds have the right aortic arch, mammals - the left).