Human heart art. Morphological features of the heart

When there is eternal spring in the soul, there is no way to contain the high spirits: it is bursting from the chest to splash out with sweet creativity. How to draw, or better yet, both together? Take a simple pencil Blank sheet paper - now you will find out everything.

Lesson #1: How to draw a heart with a pencil

We will draw a heart of roses. Draw a regular circle and divide it in half with a line. Exactly on the horizontal line, draw an uneven oval, similar to a deflated balloon. Attach a couple of curves to it at the top and bottom, like the red lines shown in the example figure.

In the lesson explaining how to draw a heart, first of all, pay attention to the red lines of the sample - these are new fragments that need to be repeated on your version of the original heart.

Draw some kind of snail in the very center of the future masterpiece. First, simply divide the uneven oval almost in half with a convex curved line. Add a few strokes: in the form of the letter “P” and from its top regular line, limited by the same oval. Don't forget to add one more stroke, very small, in the upper petal. This inverted “comma” will add volume to the drawing.

A very easy step creative process entitled "How to Draw a Heart": draw two symmetrical petals, top part which he seems to repeat invisible lines heart.

All that's left is to add three petals at the bottom of the heart. If you didn't skip math classes at school, then you know how to draw curly braces. This acquired skill will help you easily cope with the task: a couple of curves on the left and right and another, final one, with an “arrow” down the center. By the way, if you look closely at the sample, you will see that the last petal you drew will be boring without a small detail - a convex stroke that adds volume.

Erase all auxiliary, erroneous and unnecessary lines. Lesson “How to draw a heart” is completed!

Lesson #2: Heart surrounded by roses

Let’s complicate the task: let’s draw in a scarlet round dance:

Draw arbitrary contour hearts, for example, like this:

Make the first sketches of three buds at once, distributing them evenly. Start with curls, work from there lateral lines according to the example:

Each flower has its own individual uniform, which appears thanks to simple curved lines. Take a closer look and repeat them in your drawing, there is nothing complicated about it:

Let's complete the drawing of the roses by adding three or four graceful outlines to each bud.

The human heart has four chambers: two ventricles and two atria. Arterial blood flows through the left sections, venous blood flows through the right. The main function is transport; the heart muscle works like a pump, pumping blood to peripheral tissues, supplying them with oxygen and nutrients. When cardiac arrest occurs, it is diagnosed clinical death. If this condition continues for more than 5 minutes, the brain shuts down and the person dies. This is the whole importance of the proper functioning of the heart; without it, the body is not viable.

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Diagram of the structure of the heart

The heart is an organ consisting of to a greater extent from muscle tissue, it provides blood supply to all organs and tissues and has the following anatomy. Located in the left half of the chest at the level of the second to fifth rib, the average weight is 350 grams. The base of the heart is formed by the atria, pulmonary trunk and aorta, turned towards the spine, and the vessels that make up the base fix the heart in the chest cavity. The apex is formed by the left ventricle and is a rounded area facing down and to the left towards the ribs.

In addition, the heart has four surfaces:

Anterior or sternocostal.
Lower or diaphragmatic.
And two pulmonary: right and left.

The structure of the human heart is quite complex, but it can be described schematically as follows. Functionally, it is divided into two sections: right and left or venous and arterial. The four-chamber structure ensures the division of the blood supply into small and big circle. The atria are separated from the ventricles by valves that open only in the direction of blood flow. The right and left ventricles are separated by the interventricular septum, and the interatrial septum is located between the atria.

The heart wall has three layers:

The epicardium is the outer shell, tightly fused with the myocardium, and covered on top by the pericardial sac - the pericardium, which separates the heart from other organs and, due to the content of a small amount of fluid between its leaves, ensures a reduction in friction during contraction.
Myocardium - consists of muscle tissue, which is unique in its structure; it provides contraction and carries out excitation and conduction of impulses. In addition, some cells have automatism, that is, they are able to independently generate impulses that are transmitted along pathways throughout the myocardium. Muscle contraction occurs - systole.
Endocardium - covers inner surface atria and ventricles and forms the heart valves, which are folds of the endocardium consisting of connective tissue with a high content of elastic and collagen fibers.

The structure of the myocardium

The thickest layer of the heart is the muscular layer; in the area of the left ventricle it reaches a thickness of 11 to 14 mm, which is 2 times greater than the wall of the right ventricle (4 to 6 mm). In the area of the atria, the muscle layer is even smaller - 2–3 mm. The myocardium of the atria and ventricles is separated by a fibrous ring; it surrounds the right and left atrioventricular orifices. The structure of the myocardium of the atria and ventricles is also different; the former have two muscle layers, and the latter three. This indicates a greater functional load on the lower parts of the heart.

The muscle fibers of the atria form the so-called ears, which are a continuation of the chambers of the upper parts of the heart. The right and left ears are distinguished. The ventricular myocardium forms papillary muscles, from which chords extend to the mitral and tricuspid valves. They are needed so that the high pressure of the ventricles does not bend the valve leaflets into the atria and does not push blood in the opposite direction.

The interatrial and interventricular septum are formed by muscle tissue. Only the latter has a membranous part, in which there are practically no muscle fibers; it occupies 1/5 of the entire surface, the remaining 4/5 of the surface is the muscular section, reaching a thickness of up to 11 mm.

Heart valves and hemodynamics

Diagram of blood flow through the chambers of the heart

To ensure the correct sequence of blood flow, valves are placed between the chambers. The right atrium and ventricle are separated by the tricuspid valve (tricuspid), and the left by the mitral valve (bicuspid). In addition, there are valves in both the pulmonary trunk and the aorta, their function is the same - to prevent the reverse flow of blood from the arteries to the heart.

When the atria contract, blood is pushed into the ventricles, after which the tricuspid and mitral valves close, and the latter begin to contract, carrying blood into the pulmonary trunk and aorta. This is how the large and small circles of blood circulation begin, the hemodynamic mechanism for them looks as follows.

The pulmonary trunk emerges from the right ventricle, it divides into the right and left pulmonary arteries, they carry venous blood to the lungs for oxygenation. The oxygenated blood then returns through the four pulmonary veins to the left atrium. This is what the pulmonary circulation looks like.

The division of vessels into arteries and veins depends not on what kind of blood they carry, but on the direction relative to the heart. An artery is any vessel coming from the heart, and a vein is called any vessel leading to it. Therefore, in the pulmonary circulation, arteries carry venous blood, and veins carry arterial blood.

Then from the left atrium the blood enters the left ventricle, and from it into the aorta - the beginning of the great circle. Blood carries oxygen and nutrients through the arteries to the tissues; as it approaches the periphery, the diameter of the vessels decreases and gas exchange and release of nutrients occur at the capillary level. After these processes, the blood becomes venous and is directed through the veins to the heart. Two vena cava flow into the right atrium - superior and inferior. And the big circle ends.

The heart has about 60–80 such cycles per minute, with a volume of about 5–6 liters. During its entire life, it carries about 6 million liters of blood. This is a colossal work performed every second to ensure the normal life of the body.

Conducting system

Conduction system of the heart

The conduction system is responsible for the correct and consistent contraction of the myocardium by transmitting excitation along muscle fibers. It consists of a complex of formations consisting of atypical muscle cells capable of automaticity, conduction and excitation. Includes the following entities:

Sinus node (Kisa-Flaca) - it is located in the right atrium at the mouth of the vena cava, and is the main pacemaker of the human heart. It consists of specialized muscle cells (Pacemakers) capable of generating impulses at a frequency of 60–80 per minute.
Three internodal tracts and one interatrial tract arise from the sinus node (SU). The first ones transmit the impulse from the suture block to the atrioventricular one, and the second one ensures its conduction to the left atrium.
Atrioventricular node (AVN) - its task is to transmit excitation to the ventricles, but it does not do this immediately, but after such a phenomenon as atrioventricular delay. It is necessary so that the atria and ventricles do not contract at the same time, since the latter simply will not have anything to pump into the vessels.
The Hiss bundles are divided into right and left according to their location in the heart. The first innervates the right ventricle, and the left is divided into two branches - anterior and posterior and is responsible for excitation of the left ventricle.
The latest and greatest small elements The conduction system is Purkinje fibers - they are diffusely separated in the thickness of the myocardium and directly transmit the impulse to the muscle fiber.

The existence of such a clear sequence ensures normal cardiac cycle and blood supply to tissues.

Blood supply to the myocardium

Coronary arteries

The heart is an organ like others, and it also needs blood, the myocardium does not feed on blood from the cavities of the heart, for this there is a separate circulatory system, which some authors even call the third circle of blood circulation. At the beginning of the aorta, two coronary (coronary) arteries branch off to the heart: the right and left. They divide dichotomously and give off smaller branches to the myocardium. The left coronary artery supplies the anterior wall of the heart, the interventricular septum and the apex, while the right one supplies the posterolateral part of the myocardium. The outflow of blood occurs through the capillaries and then through the coronary veins to the right atrium.

A feature of the coronary circulation is that the arteries fill at the moment the myocardium relaxes, so during diastole the heart not only “rests”, but also nourishes. Disturbances in the blood flow of the heart lead to diseases such as coronary heart disease, angina pectoris and myocardial infarction.

Work of the heart

The cardiac cycle (CC) is the successive phases of systole (contraction), diastole (relaxation) and the subsequent general pause. During diastole, the heart fills with blood, first the atria and then the ventricles. After which myocardial contraction occurs, and the chambers are freed of blood. On average, the duration of atrial systole is from 0.1 to 0.17 seconds, and ventricular systole is 0.33–0.47 seconds.

Phases of the cardiac cycle

The ventricles account for more hard work, since they must push blood into vessels of smaller diameter and with such force that it reaches the periphery. Therefore, the muscle wall in them is much thicker.

The duration of the cardiac cycle depends on the number of heartbeats. So at rest it will be larger, but at physical activity less. On average, one SP lasts 0.8 seconds if the heart rate is 75 beats per minute.

Schematically, this process can be described as follows: from the superior and inferior vena cava and pulmonary veins, blood enters the atria, where pressure begins to increase and the myocardium stretches. Under the influence of these factors, atrial systole occurs. Next, the blood enters the ventricles and, according to the same principle, is pushed into the pulmonary trunk and aorta.

When the ventricles contract, the atrium is in diastole, and vice versa. But there is also certain time, in which both the ventricles and atria are simultaneously in the relaxation phase, and then in a general pause.

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.

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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

Heart shaped healthy person looks 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 connection with 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: