How to draw a real heart. Basic functions of the myocardium

Heart, cor, It is a hollow muscular organ that receives blood from the venous trunks flowing into it and drives the blood into the arterial system. The heart cavity is divided into 4 chambers: 2 atria and 2 ventricles. The left atrium and left ventricle together constitute the left, or arterial, heart according to the properties of the blood in it; the right atrium and right ventricle make up the right, or venous, heart. The contraction of the walls of the heart chambers is called systole. their relaxation - diastole.

The heart has the shape of a somewhat flattened cone. It distinguishes top, apex, base, basis, anterior superior and inferior surfaces and two edges - right and left, separating these surfaces.

Rounded apex of the heart, apex cordis, facing down, forward and to the left, reaching the fifth intercostal space at a distance of 8 - 9 cm to the left of the midline; the apex of the heart is formed entirely by the left ventricle. Base, basis cordis, facing up, back and to the right. It is formed by the atria, and in front by the aorta and pulmonary trunk. In the upper right corner of the quadrangle formed by the atria, there is a place - the entry of the superior vena cava, in the lower - the inferior vena cava; now the entry points of two right pulmonary veins are located to the left, and on the left edge of the base there are two left pulmonary veins. The anterior, or sternocostal, surface of the heart, facies sternocostalis. facing anteriorly, upward and to the left and lies behind the body of the sternum and the cartilages of the ribs from III to VI. The coronary groove, sulcus coronarius, which runs transversely to the longitudinal axis of the heart and separates the atria from the ventricles, the heart is divided into an upper section formed by the atria and a larger lower section formed by the ventricles. Walking on facies sternocostalis anterior longitudinal groove, sulcus interventricularis anterior. passes along the border between the ventricles, and most the anterior surface forms the right ventricle, the smaller - the left.

The lower, or diaphragmatic, surface, facies diaphragmatica, adjacent to the diaphragm, to its tendon center. It goes through posterior longitudinal groove, sulcus interventricularis posterior. which separates the surface of the left ventricle (larger) from the surface of the right (smaller). The anterior and posterior interventricular grooves of the heart with their lower ends merge with each other and form on the right edge of the heart, immediately to the right of the apex of the heart, heart tenderloin, incisura apicis cordis. The edges of the heart, right and left, are of unequal configuration: the right is sharper; the left edge is rounded, more blunt due to the greater thickness of the wall of the left ventricle.

It is believed that the heart is equal in size the fist of the individual concerned. Its average dimensions are: length 12-13 cm, largest diameter 9-10.5 cm, anteroposterior size 6 - 7 cm. The weight of the heart of a man is on average 300 g (1/215 of body weight), of a woman - 220 g (1/250 body weight).

Anatomy of the heart (illustrations, three-dimensional images, photographs of sections)

Images and anatomical links

Human Heart, Anatomy and Physiology

Human heart is a muscle pump that has been baffling people's minds for hundreds of years. In 2725 BC e. In Egypt, Imhotep came to the conclusion that the pulse was related to cardiac function. In 400 BC e. Hippocrates wrote about the heart as a strong muscle.

In 1628 William Harvey published an explanation of the process of blood circulation. Between 1857 and 1882, Marey and Dudgeon, independently of each other, created a machine for measuring blood pressure when hypertension was detected in a person.

IN last years molecular biology helped to discover even more complex functions of this engineering masterpiece - human heart . which confirms the words of the psalmist that you and I are “wonderfully made” (Psalm 139:14).

The term "cardiovascular" describes the heart and blood vessels of the body. Blood vessels are also sometimes called the vascular tree, or bed. In this article we will look at the structure and functions human heart .

The heart is a hollow muscular organ that is located in the central part of the chest, but most of it is to the left of the midline.

A person's heart consists of two upper chambers called atria and two lower chambers called ventricles. Structurally and functionally, the heart is divided into right and left parts; the right side pumps blood to the lungs, the left side pumps blood throughout the body.

The upper chamber, or atrium, collects blood and pumps it into the ventricle, which then expels it from the human heart into large vessels. To ensure blood flows in one direction, each ventricle has inlet and outlet valves.

Left ventricle.

Blood enters the left ventricle from the left atrium through the mitral valve, which consists of two large leaflets that open when the ventricle is relaxed (diastole).

When the filling of the ventricle is completed and it contracts, the force of contraction “presses” the blood to the bottom of the mitral valve leaflets, causing the valve to close. Thanks to this mechanism, blood flows in one direction - from the ventricle to the aorta.

The outlet valve of the left ventricle is called the aortic valve. It has three leaves, or leaflets, that open when the ventricle contracts, allowing blood to enter big circle blood circulation

As the ventricle relaxes and its pressure drops below the pressure in the aorta, blood begins to flow back (from the aorta into the ventricle).

This reverse flow of blood causes the aortic valve leaflets to fill from above and thus move closer to each other (touching each other) and slam shut. The valve closes and blood does not flow back into the left ventricle.

Right ventricle.

The inlet valve is a tricuspid valve, which by definition consists of three leaflets. It provides one-way blood flow from the right atrium to the right ventricle.

The blood is then released into the pulmonary artery through the pulmonary valve (consists of three leaflets) and flows to the lungs. The tricuspid and pulmonary valves close and open according to the same principles as the mitral and aortic valves, respectively.

The cusps of the mitral and tricuspid valves are attached to the walls of the ventricles by “cords” of tissue and muscle called chordae tendineae and papillary muscles.

These structures keep the valves from opening in reverse side, which would cause the blood to flow in the opposite direction. If these valves, threads or muscles are damaged due to disease processes, then the valves do not close completely and may “leak” (valve insufficiency).

There are also diseases that cause the valves to narrow, which in turn causes a reduction in blood flow through the valves.

As a result human heart The increased resistance is constantly overcome and it increases in size. However, over time, it depletes its reserve of strength and can no longer pump blood as efficiently, which affects the health of the entire body.

The valves can also be affected by both processes at the same time (narrowing and leaking), resulting in weakened cardiac function and impaired circulation.

Cardiac function.

The cardiac function is to pump blood through the systemic circulation (whole body) and the small circulation (pulmonary). Right part The heart pumps blood to the lungs, where carbon dioxide is removed from it and it is saturated with oxygen.

The left side of the heart pumps blood to the rest of the organs; in this way oxygen and nutrients are delivered to them. Waste also enters the bloodstream, but this time through the venous system, so that it is subsequently removed from the body by organs such as the lungs, kidneys and liver.

The contraction and relaxation of the heart is a cardiac cycle that can be felt by feeling the pulsation of blood flowing through the arteries. This can be done by pressing the arteries against the bone, for example in the wrist, lower leg, neck.

Arterial pulsation is created by the build-up of a pressure wave that flows through human arteries from the heart and causes pulsatile expansion of the arterial walls. If we count this pulsation for 60 seconds, we get the pulse rate. In a healthy adult, it is approximately 72 beats per minute (normal range is 65 to 90).

Each cardiac cycle consists of two phases: diastole and systole.

Diastole (or relaxation of the heart muscle) During this phase, the heart muscle relaxes in order to accept a certain volume of flow into the lumen heart, human blood. The atria then contract to move blood into the ventricles.

The next phase is called systole, or ventricular contraction, during which blood is pumped out of the heart. The atria begin to relax in order to accept additional blood to repeat the cycle.

You can not only feel the pulse, but also monitor the cardiac cycle by listening to heart sounds through the chest wall using a stethoscope. These sounds are described as "lub-dub", where the first "lub" sound indicates the closure of the mitral and tricuspid valves, and the second "dub" sound indicates the closure of the aortic and pulmonary valves.

Additional sounds usually indicate some kind of abnormality of the heart valve and/or muscle function. The most common sounds that indicate valve dysfunction are called murmurs.

These sounds are produced when turbulent blood flow occurs due to structural changes in the valve apparatus. Normally, blood flow is smooth, linear and non-turbulent (non-swirling).

Electrical activity of the heart in humans.

In order for the heart to beat in an orderly manner, it is equipped with nerve pacemakers (a collection of nerve cells in the atria) and a special conduction system that delivers nerve impulses to the heart muscle.

Different parts of the conduction system and even parts of the heart itself are capable of beating at different rates. The conduction system provides sequential, coordinated activation from the atria to the ventricles.

This electrical system ensures that impulses reach all parts of the heart muscle. The electrical axis of the heart is determined using electrocardiogram (ECG) data.

If you want to learn how to draw a human heart with a pencil step by step, take a few simple steps.

Step 1. Okay let's start this lesson on the human heart shall we? First draw out some guidelines and shapes so we have a nice workable wireframe to use. Start with a circle for the heart and then draw the bottom of the heart which contains the heart muscle. Three horizontal lines you see drawn there will be plugs on the pulmonary artery, pulmonary veins and left atrium. The lump you see drawn will be for the aorta.

Step 2. Okay, let's draw the actual shape of the aorta, as well as the pipes that come from this part of the heart. You will then draw out the shape for the pulmonary artery like you see here.

Step 3. Now, sketch out the shape of the vena cava that is in the vase while looking at the tube, which is all self-explanatory. The next draw is four pipes. The top tube enters the pulmonary artery, and the last three are the pulmonary veins, which are on the left side. Next sketch out the outer shape of the heart on the left side, which is also part of the heart muscle, and then draw in the veins that lie on the surface of the heart. Finally you will draw the tube for the inferior vena cava, which is located just below the lower left side of the heart.

Step 4. This is your last drawing step and all you need to do is draw out the remaining actual shape of the human heart and then draw in the superficial veins. Lastly, draw the tubes for the pulmonary vein and left atrium. Erase all the guidelines that are visible to clear your drawing of the human heart.

To ensure adequate nutrition internal organs, the heart pumps an average of seven tons of blood per day. Its size is equal to a clenched fist. Throughout life, this organ makes approximately 2.55 billion beats. The final formation of the heart occurs by the 10th week of intrauterine development. After birth, the type of hemodynamics changes dramatically - from feeding on the mother’s placenta to independent, pulmonary breathing.

Read in this article

Muscle fibers (myocardium) are the predominant type of heart cells. They make up its bulk and are located in the middle layer. The outside of the organ is covered with epicardium. It wraps at the level of the attachment of the aorta and pulmonary artery, heading downwards. In this way, the pericardial sac is formed. It contains about 20 - 40 ml of clear liquid, which prevents the leaves from sticking together and being injured during contractions.

The inner membrane (endocardium) folds in half at the transition of the atria into the ventricles, the mouths of the aortic and pulmonary trunk, forming valves. Their valves are attached to a ring of connective tissue, and the free part moves with the blood flow. In order to prevent the parts from everting into the atrium, threads (chords) are attached to them, extending from the papillary muscles of the ventricles.

The heart has the following structure:

three membranes - endocardium, myocardium, epicardium;
pericardial sac;
chambers with arterial blood - left atrium (LA) and ventricle (LV);
sections with venous blood - right atrium (RA) and ventricle (RV);
valves between the LA and LV (mitral) and tricuspid on the right;
two valves separate the ventricles and large vessels (aortic on the left and pulmonary artery on the right);
the septum divides the heart into right and left halves;
efferent vessels, arteries - pulmonary (venous blood from the pancreas), aorta (arterial from the left ventricle);
afferent veins - pulmonary (with arterial blood) enter the LA, vena cava flow into the RA.

Internal anatomy and structural features of valves, atria, ventricles

Each part of the heart has its own function and anatomical features. In general, the LV is more powerful (compared to the right), as it forces blood into the arteries, overcoming the high resistance of the vascular walls. The PP is more developed than the left, it receives blood from the whole body, and the left one only from the lungs.

Which side of a person's heart is on?

In humans, the heart is located on the left side in the center of the chest. The main part is located in this area - 75% of the total volume. One third extends beyond the midline into the right half. In this case, the axis of the heart is inclined (oblique direction). This situation is considered classic, as it occurs in the vast majority of adults. But options are also possible:

dextrocardia (right side);
almost horizontal - with a wide, short chest;
close to vertical - for thin people.

Where is a person's heart located?

The human heart is located in the chest between the lungs. It is adjacent to the sternum from the inside, and is limited below by the diaphragm. It is surrounded by the pericardium, the pericardium. Pain in the heart area appears on the left near the mammary gland. The top is projected there. But with angina, patients feel pain behind the sternum, and it spreads along the left side of the chest.

Where is the heart located in the human body?

The heart in the human body is located in the center of the chest, but its main part goes into the left half, and only one third is located on the right side. For most it has an angle of inclination, but for fat people its position is closer to horizontal, and for thin people it is closer to vertical.

Location of the heart in the human chest

In humans, the heart is located in the chest in such a way that its anterior and lateral surfaces are in contact with the lungs, and its posterior and inferior surfaces are in contact with the diaphragm. The base of the heart (from above) passes into large vessels - the aorta, pulmonary artery. The apex is the lowest part, it approximately corresponds to the 4-5 space between the ribs. It can be found in this area by lowering an imaginary perpendicular from the center of the left collarbone.

The external structure of the heart refers to its chambers; it contains two atria and two ventricles. They are separated by partitions. The pulmonary veins, the vena cava, enter the heart, and the arteries of the lungs, the aorta, carry the blood out. Between the large vessels, at the border of the atria and ventricles of the same name, there are valves:

aortic;
pulmonary artery;
mitral (left);
tricuspid (between the right parts).

The heart is surrounded by a cavity containing a small amount of fluid. It is formed by the pericardial layers.

If you clench your fist, you can imagine exactly the appearance of a heart. In this case, the part that is located at the wrist joint will be its base, and the acute angle between the first and thumb- the top. What is important is that its size is also very close to a clenched fist.

This is what a human heart looks like

Borders of the heart and their projection onto the surface of the chest

The boundaries of the heart are found by percussion, by tapping; radiography or echocardiography helps to determine them more accurately. The projections of the cardiac contour onto the surface of the chest are:

right – 10 mm to the right of the sternum;
left – 2 cm inward from the perpendicular from the center of the collarbone;
apex – 5th intercostal space;
base (upper) – 3rd rib.

What tissues make up the heart?

The heart consists of the following types of tissue:

muscle - the main one, is called the myocardium, and the cells are cardiomyocytes;
connective – valves, chords (threads that hold the valves), outer (epicardial) layer;
epithelium – inner lining (endocardium).

Surfaces of the human heart

The human heart has the following surfaces:

ribs, sternum – anterior;
pulmonary – lateral;
diaphragmatic – lower.

Apex and base of the heart

The apex of the heart is directed down and to the left, its localization is the 5th intercostal space. It represents the top of the cone. Wide part(base) is located on top, closer to the collarbones, and is projected at the level of the 3rd rib.

Human heart shape

The shape of a healthy person's heart is like a cone. Its tip is directed at an acute angle down and to the left of the center of the sternum. The base contains the mouths of large vessels and is located at the level of the 3rd rib.

Right atrium

Receives blood from the vena cava. Next to them is the foramen ovale, which connects the RA and LA in the fetal heart. In a newborn, it closes after the pulmonary blood flow opens, and then completely heals. During systole (contraction), venous blood passes into the pancreas through the tricuspid valve. The RA has a fairly powerful myocardium and a cubic shape.

Left atrium

Arterial blood from the lungs passes into the LA through 4 pulmonary veins and then flows through the opening into the LV. The walls of the LA are 2 times thinner than those of the right one. The shape of the LP is similar to a cylinder.

Right ventricle

It looks like an inverted pyramid. The capacity of the pancreas is about 210 ml. It can be divided into two parts - the arterial (pulmonary) cone and the ventricular cavity itself. In the upper part there are two valves: the tricuspid and the pulmonary trunk.

Left ventricle

It looks like an inverted cone, its lower part forms the top of the heart. The thickness of the myocardium is the largest - 12 mm. There are two openings at the top - for connecting to the aorta and LA. Both of them are covered by valves - the aortic and mitral.

Why are the walls of the atria thinner than the walls of the ventricles?

The thickness of the walls of the atrium is less, they are thinner, since they only need to push blood into the ventricles. The right ventricle follows them in strength; it throws its contents into the neighboring lungs, and the left one is the largest in terms of the size of its walls. It pumps blood to the aorta, where there is high pressure.

Tricuspid valve

The right atrioventricular valve consists of a sealed ring that limits the opening and leaflets; there may be not 3, but from 2 to 6.

Half of the people have a tricuspid configuration.

The function of this valve is to prevent the reflux of blood into the RA during RV systole.

Pulmonary valve

It prevents blood from passing back into the pancreas after it contracts. The composition contains valves similar in shape to a crescent. In the middle of each there is a knot that seals the closure.

Mitral valve

It has two doors, one is in the front and the other is in the back. When the valve is open, blood flows from the LA to the LV. When the ventricle contracts, its parts close together to allow blood to pass into the aorta.

Aortic valve

Formed by three semilunar-shaped flaps. Like the pulmonary one, it does not contain threads that hold the valves in place. In the area where the valve is located, the aorta expands and has depressions called sinuses.

Adult heart weight

Depending on body type and total weight body weight of the heart in an adult varies from 200 to 330 g. In men, it is on average 30-50 g heavier than in women.

Diagram of blood circulation

Gas exchange occurs in the alveoli of the lungs. They receive venous blood from the pulmonary artery emerging from the pancreas. Despite the name, the pulmonary arteries carry venous blood. After the release of carbon dioxide and oxygen saturation through the pulmonary veins, the blood passes into the left atrium. This is how a small circle of blood flow, called pulmonary, is formed.

The large circle covers the entire body as a whole. From the LV, arterial blood spreads to all vessels, nourishing the tissues. Deprived of oxygen, venous blood flows from the vena cava into the RA, then into the RV. The circles close together, ensuring a continuous flow.

In order for blood to enter the myocardium, it must first pass into the aorta and then into the two coronary arteries. They are named so because of the shape of the branches, reminiscent of a crown (crown). Venous blood from the heart muscle predominantly enters the coronary sinus. It opens into the right atrium. This circle of blood circulation is considered the third, coronary.

Watch the video about the structure of the human heart:

What is special about the structure of a child’s heart?

Until the age of six, the heart is spherical due to the large atria. Its walls are easily stretched, they are much thinner than those of adults. A network of tendon threads is gradually formed, fixing the valve leaflets and papillary muscles. Full development of all heart structures ends by age 20.

The position of the newborn's heart in the chest is initially oblique, adjacent to the anterior surface. This is caused by an increase in the volume of lung tissue and a decrease in the mass of the thymus gland.

Until two years of age, the heart impulse forms the right ventricle, and then part of the left. The atria are the leaders in growth rate up to 2 years, and the ventricles after 10 years. Up to ten years, the LV is ahead of the right.

Basic functions of the myocardium

The heart muscle differs in structure from all others, as it has several unique properties:

Automatism is excitation under the influence of one’s own bioelectric impulses. They first form in the sinus node. He is the main pacemaker, generating about 60 - 80 signals per minute. The underlying cells of the conducting system are nodes of the 2nd and 3rd order.
Conduction - impulses from the site of formation can spread from the sinus node to the RA, LA, atrioventricular node, and along the ventricular myocardium.
Excitability - in response to external and internal stimuli, the myocardium is activated.
Contractility is the ability to contract when excited. This function creates the pumping capabilities of the heart. The force with which the myocardium reacts to an electrical stimulus depends on the pressure in the aorta, the degree of stretching of the fibers in diastole, and the volume of blood in the chambers.

The functioning of the heart goes through three stages:

Contraction of the RA, LA and relaxation of the RV and LV with the opening of the valves between them. Transition of blood into the ventricles.
Ventricular systole - the valves of the blood vessels open, blood flows into the aorta and pulmonary artery.
General relaxation (diastole) - blood fills the atria and presses on the valves (mitral and tricuspid) until they open.

During the period of contraction of the ventricles, the valves between them and the atria are closed by blood pressure. In diastole, the pressure in the ventricles drops, it becomes lower than in large vessels, then parts of the pulmonary and aortic valves close so that the blood flow does not return.

Heart cycle

There are 2 stages in the heart cycle: contraction and relaxation. The first is called systole and also includes 2 phases:

compression of the atria to fill the ventricles (lasts 0.1 sec.);
the work of the ventricular part and the release of blood into large vessels (about 0.5 sec.).

Then comes relaxation - diastole (0.36 sec). Cells change polarity to respond to the next impulse (repolarization), and the blood vessels of the myocardium bring nutrition. During this period, the atria begin to fill.

The heart ensures the movement of blood through the large and small circles thanks to the coordinated work of the atria, ventricles, great vessels and valves. The myocardium has the ability to generate an electrical impulse and conduct it from the nodes of automaticity to the cells of the ventricles. In response to the signal, muscle fibers become active and contract. Cardiac cycle consists of a systolic and diastolic period.

Useful video

Watch the video about the work of the human heart:

Functions of the heart - why do we need a heart?

Our blood provides the entire body with oxygen and nutrients. In addition, it also has a cleansing function, helping in the removal of metabolic waste.

The function of the heart is to pump blood through blood vessels.

How much blood does the human heart pump?

The human heart pumps from 7,000 to 10,000 liters of blood in one day. This amounts to approximately 3 million liters per year. That works out to 200 million liters over a lifetime!

The amount of blood pumped within a minute depends on the current physical and emotional load - the greater the load, the more blood the body requires. So the heart can conduct from 5 to 30 liters through itself in one minute.

The circulatory system consists of about 65 thousand vessels, their total length is about 100 thousand kilometers! Yes, we didn't make a mistake.

Circulatory system

The human cardiovascular system is formed by two circles of blood circulation. With each heartbeat, blood moves in both circles at once.

Pulmonary circulation

Deoxygenated blood from the superior and inferior vena cava enters the right atrium and then into the right ventricle.
From the right ventricle, blood is pushed into the pulmonary trunk. The pulmonary arteries carry blood directly to the lungs (to the pulmonary capillaries), where it receives oxygen and releases carbon dioxide.
Having received enough oxygen, the blood returns to the left atrium of the heart through the pulmonary veins.

Systemic circulation

From the left atrium, blood moves into the left ventricle, from where it is subsequently pumped through the aorta into the systemic circulation.
After going through a difficult path, the blood again arrives through the vena cava to the right atrium of the heart.

Normally, the amount of blood pushed out of the ventricles of the heart is the same with each contraction. Thus, an equal volume of blood simultaneously enters the greater and lesser circulation.

What is the difference between veins and arteries?

Veins are designed to transport blood to the heart, and the job of arteries is to supply blood in the opposite direction.
In veins, blood pressure is lower than in arteries. Accordingly, the walls of arteries are more elastic and dense.
Arteries saturate “fresh” tissue, and veins take away “waste” blood.
In the case of vascular damage, arterial or venous bleeding can be distinguished by its intensity and the color of the blood. Arterial - strong, pulsating, beating like a “fountain”, the color of the blood is bright. Venous - bleeding of constant intensity (continuous flow), the color of the blood is dark.

The weight of a human heart is only about 300 grams (on average 250 grams for women and 330 grams for men). Despite the relatively low weight, this is undoubtedly main muscle in the human body and the basis of its life activity. The size of the heart is indeed approximately equal to a human fist. Athletes' hearts can be one and a half times larger than those of the average person.

Anatomical structure

The heart is located in the middle of the chest at the level of 5-8 vertebrae.

Normally, the lower part of the heart is located mostly in the left side of the chest. There is a variant of congenital pathology in which all organs are mirrored. It is called transposition of internal organs. The lung, next to which the heart is located (normally the left one), is smaller in size relative to the other half.

The back surface of the heart is located near the spinal column, and the front surface is reliably protected by the sternum and ribs.

The human heart consists of four independent cavities (chambers) divided by partitions:

two upper ones - the left and right atria;
and two lower ones - the left and right ventricles.

The right side of the heart includes the right atrium and ventricle. The left half of the heart is represented, respectively, by the left ventricle and atrium.

The inferior and superior vena cava enter the right atrium, and the pulmonary veins enter the left atrium. From right ventricle the pulmonary arteries (also called the pulmonary trunk) emerge. From left ventricle the ascending aorta rises.

The heart has protection from overstretching and other organs, which is called the pericardium or pericardial sac (a kind of membrane in which the organ is enclosed). It has two layers: an outer dense, durable connective tissue called fibrous membrane of the pericardium and internal ( serous pericardium).

Thus, the heart itself consists of three layers: epicardium, myocardium, endocardium. It is the contraction of the myocardium that pumps blood through the vessels of the body.

The walls of the left ventricle are approximately three times larger than the walls of the right! Explained this fact in that the function of the left ventricle is to push blood into the systemic circulation, where the resistance and pressure are much higher than in the pulmonary circulation.

The device of heart valves

Special heart valves allow you to constantly maintain blood flow in the correct (unidirectional) direction. The valves alternately open and close, either letting blood through or blocking its path. Interestingly, all four valves are located along the same plane.

Between the right atrium and the right ventricle is located tricuspid (tricuspid) valve. It contains three special leaflet plates that, during contraction of the right ventricle, can provide protection from the reverse flow (regurgitation) of blood into the atrium.

Works in a similar way mitral valve, only it is located on the left side of the heart and is bicuspid in its structure.

Aortic valve prevents the reverse flow of blood from the aorta into the left ventricle. Interestingly, when the left ventricle contracts, the aortic valve opens as a result of blood pressure on it, so it moves into the aorta. After which, during diastole (the period of relaxation of the heart), the reverse flow of blood from the artery promotes the closure of the valves.

Normally, the aortic valve has three leaflets. The most common congenital heart abnormality is bicuspid aortic valve. This pathology occurs in 2% of the human population.

Pulmonary valve at the moment of contraction of the right ventricle, it allows blood to flow into the pulmonary trunk, and during diastole it does not allow it to flow in the opposite direction. It also consists of three doors.

Cardiac vessels and coronary circulation

The human heart requires nutrition and oxygen, just like any other organ. The vessels that supply (nourish) the heart with blood are called coronary or coronary. These vessels branch from the base of the aorta.

The coronary arteries supply the heart with blood, and the coronary veins remove deoxygenated blood. Those arteries that are located on the surface of the heart are called epicardial. Subendocardial arteries are called coronary arteries hidden deep in the myocardium.

Most of the blood outflow from the myocardium occurs through three cardiac veins: large, middle and small. Forming the coronary sinus, they flow into the right atrium. The anterior and small veins of the heart deliver blood directly to the right atrium.

Coronary arteries are divided into two types - right and left. The latter consists of the anterior interventricular and circumflex arteries. The great cardiac vein branches into the posterior, middle and small veins of the heart.

Even absolutely healthy people have their own unique features coronary circulation. In reality, the vessels may look and be located differently than shown in the picture.

How does the heart develop (form)?

Pulse path

This system ensures automatism of the heart - excitation of impulses generated in cardiomyocytes without an external stimulus. In a healthy heart main source impulses - sinoatrial (sinus) node. He is the leader and blocks the impulses from all other pacemakers. But if any disease occurs that leads to sick sinus syndrome, then other parts of the heart take over its function. Thus, the atrioventricular node (automatic center of the second order) and the His bundle (AC of the third order) are able to activate when the sinus node is weak. There are cases when secondary nodes enhance their own automaticity even during normal operation of the sinus node.

Sinus node located in the superior posterior wall of the right atrium in close proximity from the mouth of the superior vena cava. This node initiates pulses with a frequency of approximately 80-100 times per minute.

Atrioventricular node (AV) located in the lower part of the right atrium in the atrioventricular septum. This septum prevents the impulse from propagating directly into the ventricles, bypassing the AV node. If the sinus node is weakened, then the atrioventricular node will take over its function and begin to transmit impulses to the heart muscle at a frequency of 40-60 contractions per minute.

Next, the atrioventricular node passes into His bundle(atrioventricular bundle divided into two legs). The right leg rushes towards the right ventricle. The left leg is divided into two more halves.

The situation with the left bundle branch has not been fully studied. It is believed that the left leg with fibers from the anterior branch rushes to the anterior and lateral wall of the left ventricle, and the posterior branch supplies fibers to the posterior wall of the left ventricle and the lower parts of the lateral wall.

In case of weakness of the sinus node and atrioventricular block, the His bundle is capable of creating impulses at a speed of 30-40 per minute.

The conducting system deepens and further branches into smaller branches, eventually moving into Purkinje fibers, which penetrate the entire myocardium and serve as a transmission mechanism for contraction of the ventricular muscles. Purkinje fibers are capable of initiating impulses at a frequency of 15-20 per minute.

Exceptionally trained athletes can have normal resting heart rates down to the lowest recorded figure of just 28 beats per minute! However, for the average person, even one leading a very active lifestyle, a heart rate below 50 beats per minute may be a sign of bradycardia. If your heart rate is this low, you should be examined by a cardiologist.

Heartbeat

A newborn's heart rate may be around 120 beats per minute. As a person gets older, the pulse stabilizes between 60 and 100 beats per minute. Well trained athletes we're talking about about people with well-trained cardiovascular and respiratory systems) have a pulse of 40 to 100 beats per minute.

Controls heart rhythm nervous system- the sympathetic strengthens contractions, and the parasympathetic weakens.

Cardiac activity, to a certain extent, depends on the content of calcium and potassium ions in the blood. Other biologically active substances also contribute to the regulation of heart rhythm. Our heart may begin to beat faster under the influence of endorphins and hormones released when listening to our favorite music or kissing.

In addition, the endocrine system can have a significant impact on the heart rhythm - both the frequency of contractions and their strength. For example, the release of the well-known adrenaline by the adrenal glands causes an increase in heart rate. The hormone with the opposite effect is acetylcholine.

Heart sounds

One of the most simple methods diagnosing heart disease is by listening to the chest using a stethoscope (auscultation).

In a healthy heart, during standard auscultation, only two heart sounds are heard - they are called S1 and S2:

S1 is the sound heard when the atrioventricular (mitral and tricuspid) valves close during ventricular systole (contraction).
S2 - the sound heard when the semilunar (aortic and pulmonary) valves close during diastole (relaxation) of the ventricles.

Each sound consists of two components, but to the human ear they merge into one due to the very short period of time between them. If, under normal conditions of auscultation, additional tones become audible, this may indicate some kind of disease of the cardiovascular system.

Sometimes additional abnormal sounds may be heard in the heart, called a heart murmur. As a rule, the presence of murmurs indicates some kind of heart pathology. For example, noise can cause blood to flow back in the opposite direction (regurgitation) due to malfunction or damage to a valve. However, noise is not always a symptom of a disease. To clarify the reasons for the appearance of additional sounds in the heart, it is worth doing echocardiography (ultrasound of the heart).

Heart diseases

It is not surprising that the number of cardiovascular diseases. The heart is a complex organ that actually rests (if it can be called rest) only in the intervals between heartbeats. Any complex and constantly working mechanism itself requires as much as possible careful attitude and ongoing prevention.

Just imagine what a monstrous burden falls on the heart given our lifestyle and low-quality, abundant nutrition. Interestingly, mortality from cardiovascular diseases is quite high in countries with high level income.

The huge amounts of food consumed by the population of wealthy countries and the endless pursuit of money, as well as the associated stress, destroy our hearts. Another reason for the spread of cardiovascular diseases is physical inactivity - catastrophically low physical activity, destroying the entire body. Or, on the contrary, an illiterate passion for heavy physical exercise, often occurring in the background, the presence of which people do not even suspect and manage to die right during “health” activities.

Lifestyle and heart health

The main factors that increase the risk of developing cardiovascular diseases are:

Obesity.
High blood pressure.
Increased blood cholesterol levels.
Physical inactivity or excessive physical activity.
Abundant, low-quality food.
Depressed emotional condition and stress.

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