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The cardiovascular system
The presentation was made by Elena Shakhova, an 8th grade student

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The cardiovascular system consists of the circulatory and lymphatic systems. The circulatory system consists of the heart and blood vessels. The vessels that carry blood from the heart to the organs are arteries, and the vessels that bring blood to the heart are veins. The lymphatic system consists of organs of the immune system and lymphatic pathways.

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Heart
a hollow muscular organ weighing 240-330 g, cone-shaped, pumping blood into the arteries and receiving venous blood. The heart is located in the chest cavity between the lungs, in the lower mediastinum. has two atria, two ventricles and four valves; receives blood from two vena cava and four pulmonary veins, and throws it into the aorta and pulmonary trunk. The heart pumps 9 liters of blood per day, making from 60 to 160 beats per minute. There are pericardium, myocardium and endocardium. The heart is located in the cardiac sac - the pericardium. Cardiac muscle - the myocardium consists of several layers of muscle fibers; there are more of them in the ventricles than in the atria. These fibers, contracting, push blood from the atria into the ventricles and from the ventricles into the vessels. The internal cavities of the heart and valves are lined by the endocardium.

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Inside, the heart is divided by partitions into four chambers. The two atria are divided by the interatrial septum into the left and right atria. The left and right ventricles of the heart are separated by the interventricular septum. Normally, the left and right parts of the heart are completely separate. The atria and ventricles have different functions. The atria store blood that flows into the heart. When the volume of this blood is sufficient, it is pushed into the ventricles. And the ventricles push blood into the arteries, through which it moves throughout the body. The ventricles have to do more hard work, so the muscle layer in the ventricles is much thicker than in the atria. The atria and ventricles on each side of the heart are connected by the atrioventricular orifice. Blood moves through the heart in only one direction. In the large circle of blood circulation from the left part of the heart (left atrium and left ventricle) to the right, and in the small circle from the right to the left. The correct direction is ensured by the valve apparatus of the heart: tricuspid pulmonary mitral aortic valves.

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Systemic and pulmonary circulation
The systemic circulation begins in the left ventricle, passes through all internal organs and ends in the right atrium. The pulmonary circulation begins in the right ventricle, passes through the lungs and ends in the left atrium.

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Vessels of the systemic circulation
The systemic circulation begins with the largest vessel – the aorta. The aorta is divided into the ascending part, the aortic arch and the descending part. The ascending section begins with a significant expansion - the aortic bulb. The length of this section is about 6 cm. It lies behind the pulmonary trunk and, together with it, is covered by the pericardium. Aortic arch - at the level of the manubrium of the sternum, the aorta bends posteriorly and to the left, spreading over the left main bronchus. The descending section begins at the level of the IV thoracic vertebra. It lies in the posterior mediastinum, at the beginning to the left of the spinal column, gradually deviating to the right, at the level of the XII thoracic vertebra, located anterior to the spine, along the midline. There are two sections of the descending aorta: the thoracic aorta and the abdominal aorta, the division takes place along the aortic notch of the diaphragm. At the level of the IV lumbar vertebra, the descending aorta is divided into its terminal branches - the right and left common iliac arteries, the so-called aortic bifurcation. From the aorta, blood flows through its numerous paired and unpaired branches - arteries - to all parts of the body.

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Vessels of the pulmonary circulation
The pulmonary circulation includes: the pulmonary trunk, the right and left pulmonary arteries and their branches, the microcircular bed of the lungs, two right and two left pulmonary veins.

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Coronary circle of blood circulation
The coronary circle of blood circulation is cardiac. It includes the vessels of the heart itself to supply blood to the heart muscle. The coronary circle is characterized by the following features: V High pressure, since the coronary vessels begin from the aorta. The coronary vessels form a dense capillary network in the heart muscle with many end-type vessels, which poses a danger if they become blocked, especially in old age. Blood enters the coronary vessels during diastole. This is due to the fact that in the systole phase the mouths of the capillaries are closed by the semilunar valves of the aorta, and also because during systole the myocardium contracts, the coronary vessels are compressed and the flow of blood into them is difficult. During diastole, the myoglobin of the heart muscle is saturated with oxygen, which it very easily gives to the heart in phase. The presence of arteriolovenular anastomoses and arteriolosinusoidal shunts V Special regulation of the tone of the coronary vessels

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Arteries
The blood in the arteries is under high pressure. The presence of elastic fibers allows the arteries to pulsate - expand with each heartbeat and collapse when blood pressure drops. Large arteries are divided into medium and small (arterioles), the wall of which has a muscular layer innervated by autonomic vasoconstrictor and vasodilator nerves. The wall of the arteries consists of the inner, middle and outer membranes. The middle shell is separated by an internal elastic membrane from the inner shell and an outer elastic membrane from the outer shell.

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Vienna
Having entered the capillaries from the arteries and passed through them, the blood enters the venous system. It first enters very small vessels called venules, which are equivalent to arterioles. The blood continues its journey through small veins and returns to the heart through veins that are large enough to be visible under the skin. These veins contain valves that prevent blood from returning to the tissues. The valves are shaped like a small crescent moon protruding into the lumen of the duct, causing blood to flow in only one direction. Blood enters the venous system, passing through the smallest vessels - capillaries. Exchanges between blood and extracellular fluid occur through the walls of capillaries. Most of the tissue fluid returns to the venous capillaries, and some enters the lymphatic channel. Larger venous vessels can contract or dilate, regulating the flow of blood into them. The movement of the veins is largely due to the tone of the skeletal muscles surrounding the veins, which contract and compress the veins. The pulsation of the arteries adjacent to the veins has a pump effect.

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Lymphatic system
The lymphatic system is a part of the vascular system that complements the cardiovascular system. It plays an important role in metabolism and cleansing of body cells and tissues. Unlike the circulatory system, the lymphatic system is not closed and does not have a central pump. The lymph circulating in it moves slowly and under low pressure. The lymphatic system begins in the periphery with “blind” lymphatic capillaries, which become thin lymphatic vessels, which connect into collecting ducts that empty into large veins at the base of the neck. Lymph flowing through the lymphatic vessels is “filtered” in the lymph nodes, which are located along the path of the lymphatic vessels.

THE CARDIOVASCULAR SYSTEM

1. Structure

cardiovascular

• Heart.
• Blood vessels.

2. Work of the heart and blood vessels:

• Cardiac cycle
• Circulation circles
• Blood pressure
• Pulse

Structure of the cardiovascular system. The cardiovascular system is formed by:

• Heart
• Blood vessels

In humans, the heart is located near the center of the chest cavity, it is shifted 2/3 to the left side. The weight of a man's heart is on average 300g, a woman's - 250g.

The heart has the shape of a cone, flattened in the anteroposterior direction. It distinguishes between the top and the base. The apex is the pointed part of the heart, directed down and to the left and slightly forward. The base is the expanded part of the heart, facing up and to the right and slightly back. It consists of strong elastic tissue - the heart muscle (myocardium), which contracts rhythmically throughout life, sending blood through the arteries and capillaries to the tissues of the body.

Structure of the heart

The HEART is a powerful muscular organ that pumps blood through a system of cavities (chambers) and valves into a closed distribution system called the circulatory system.

The heart wall consists of three layers:

internal - endocardium,

middle - myocardium and

external - epicardium.

Endocardium Endocardium It lines the inside surface of the chambers of the heart; it is formed by a special type of epithelial tissue - endothelium. The endothelium has a very smooth, shiny surface, which reduces friction as blood moves through the heart. Myocardium makes up the bulk of the heart wall. It is formed by striated cardiac muscle tissue, the fibers of which, in turn, are arranged in several layers. The atrial myocardium is much thinner than the ventricular myocardium. The myocardium of the left ventricle is three times thicker than the myocardium of the right ventricle. The degree of development of the myocardium depends on the amount of work performed by the chambers of the heart. The myocardium of the atria and ventricles is separated by a layer of connective tissue (annulus fibrosus), which makes it possible to alternately contract the atria and ventricles. Epicard- This is a special serous membrane of the heart, formed by connective and epithelial tissue. Heart chambers Heart valves

The functioning of the heart valves ensures one-way movement

in heart.

Blood vessels are a closed system of hollow elastic tubes of various structures, diameters and mechanical properties. Vessels of the circulatory system Arteries carry blood from the heart, and veins return blood to the heart. Between the arterial and venous sections of the circulatory system there is a microvasculature connecting them, including arterioles, venules, and capillaries.

CAPILLARIES

ARTERIES The wall of the artery consists of three membranes: inner, middle and outer. The inner lining is the endothelium (squamous epithelium with a very smooth surface). The middle layer is formed by smooth muscle tissue and contains well-developed elastic fibers. Smooth muscle fibers change the lumen of the artery. Elastic fibers provide firmness, elasticity and strength to the walls of arteries. The outer shell consists of loose fibrous connective tissue, which plays a protective role and helps fix the arteries in a certain position. As they move away from the heart, the arteries branch strongly, eventually forming the smallest ones - arterioles. CAPILLARIES The thin wall of capillaries is formed by only one layer of flat endothelial cells. Blood gases, metabolic products, nutrients, vitamins, hormones and white blood cells (if necessary) easily pass through it. Veins The second feature of veins is the large number of venous valves on the inner wall. They are arranged in pairs in the form of two semilunar folds. Venous valves prevent blood from flowing back in the veins when skeletal muscles work. There are no venous valves in the superior vena cava, pulmonary veins, veins of the brain and heart.

The structure of the wall of veins is fundamentally the same as that of arteries. But the peculiarity is the significantly smaller wall thickness due to the thinness of the middle layer. It has much less muscle and elastic fibers due to low blood pressure in the veins.

CIRCLES OF BLOOD CIRCULATION Cardiac cycle. The sequence of contractions of the chambers of the heart is called the cardiac cycle. During the cycle, each of the four chambers goes through not only a contraction phase (systole), but also a relaxation phase (diastole). The atria contract first: first the right one, almost immediately followed by the left one. These contractions ensure that the relaxed ventricles are quickly filled with blood. Then the ventricles contract, forcefully pushing out the blood they contain. At this time, the atria relax and fill with blood from the veins. Each such cycle lasts on average 6/7 seconds. Heart work in numbers In children and adults, the heart contracts at different frequencies: in children under one year old - 100-200 beats per minute, at 10 years old - 90, and at 20 years old and older - 60-70; after 60 years, the number of contractions becomes more frequent and reaches 90-95. For athletes-runners, while running at sports competitions, the heart rate can reach up to 250 per minute; when the running is over, the heart gradually calms down, and soon its normal rhythm of contractions is established. With each contraction, the heart throws out about 60–75 ml of blood, and per minute (with an average contraction frequency of 70 per minute) – 4–5 liters. Over 70 years, the heart produces more than 2.5 billion contractions and pumps approximately 156 million liters of blood. The work of the heart, like any other work, is measured by multiplying the weight of the lifted load (in kilograms) by the height (in meters). Let's try to determine its work. During the day, if a person does not do hard work, the heart contracts over 100,000 times; per year - about 40,000,000 times, and over 70 years of life - almost 3,000,000,000 times. What an impressive figure - three billion cuts! Now multiply the heart rate by the amount of blood ejected, and you will see what a huge amount of it it pumps. After making the calculation, you will be convinced that in an hour the heart pumps about 300 liters of blood, in a day - over 7000 liters, in a year - 2,500,000, and in 70 years of life - 175,000,000 liters. The blood pumped by the heart during a person's life can fill 4,375 railway tanks. If the heart pumped not blood, but water, then from the water it pumped over 70 years it would be possible to create a lake 2.5 m deep, 7 km wide and 10 km long. The work of the heart is very significant. So, with one beat, work is done with the help of which you can lift a load of 200 g to a height of 1 m. In 1 minute, the heart would lift this load 70 m, i.e. to the height of almost a twenty-story building. If it were possible to use the work of the heart, then in 8 hours it would be possible to lift a person to the height of the Moscow University building (about 240 m), and in 30-31 days to the top of Chomolungma - the highest point on the globe (8848 m)! BLOOD PRESSURE The rhythmic work of the heart creates and maintains a pressure difference in the blood vessels. When the heart contracts, blood is forced into the arteries under pressure. During the passage of blood through the vessels, pressure energy is wasted. Therefore, blood pressure gradually decreases. In the aorta it is highest 120-150 mmHg, in arteries - up to 120 mmHg, in capillaries up to 20, and in the vena cava from 3-8 mmHg. to minimum (-5) (below atmospheric). According to the law of physics, liquid moves from an area with higher pressure to an area with lower pressure. Arterial blood pressure is not a constant value. It pulsates in time with the contractions of the heart: at the moment of systole, the pressure rises to 120-130 mmHg. (systolic pressure), and during diastole it decreases to 80-90 mmHg. (diastolic). These pulse pressure fluctuations occur simultaneously with pulse fluctuations of the arterial wall. A person's blood pressure is measured in the brachial artery, comparing it with atmospheric pressure. HOW TO MEASURE BLOOD PRESSURE Air is pumped into the pressure gauge cuff until the pulse on the wrist disappears. Now the brachial artery is compressed by great external pressure and blood does not flow through it. Then, gradually releasing air from the cuff, watch for the appearance of a pulse. At this moment, the pressure in the artery becomes slightly greater than the pressure in the cuff, and the blood, and with it the pulse wave, begins to reach the wrist. The pressure gauge readings at this time will characterize the blood pressure in the brachial artery. PULSE Pulse. When the ventricles contract, blood is ejected into the aorta, increasing its pressure. The wave that arises in its wall propagates at a certain speed from the aorta to the arteries. Rhythmic oscillations of the arterial wall. Caused by an increase in pressure in the aorta during systole, called the pulse.

The pulse can be detected in places where large arteries come close to the surface of the body (wrist, temples, sides of the neck).

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. The main function of the cardiovascular system is to ensure constant movement of blood through the vessels

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The cardiovascular system is represented by the heart, blood vessels, lymphatic vessels

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. HEART

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. sternum apex of the heart base of the heart midline 2/3 1/3 200 g - F 250 g - M

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. The heart is located in the pericardial sac - pericardium pericardium (outer layer) pericardium epicardium pericardial cavity Epicardium (inner layer)

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. Covers of the heart Epicardium (outer) Endocardium (inner) Myocardium (middle)

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; 3) protection from invading microorganisms and foreign cells. Chambers of the heart Right ventricle Left ventricle Right atrium Left atrium The human heart has four chambers: two atria - left and right and two ventricles - left and right. The atria are located above the ventricles.

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages RA LP RV LV Aorta Pulmonary arteries SVC IVC 4 pulmonary veins

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Valve - formed by the folds of its inner lining, ensures unidirectional blood flow by blocking the venous and arterial passages. Heart valves are formed by folds of the endocardium (inner lining of the heart). tricuspid valve - between the RA and RV bicuspid valve (mitral) - between the LA and LV semilunar valves - between the ventricles and the arteries of the RV LV RA LP aorta pulmonary artery

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ensure the movement of blood in one direction: from the atria to the ventricles, from the ventricles to the arteries Functions of heart valves

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transport of nutrients, gases, hormones and metabolic products to and from cells; 2) regulation of body temperature; m Blood supply to the heart Oxygen and nutrients enter the heart with blood through the coronary arteries Coronary arteries

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The valve, formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. The conduction system of the heart consists of special neuromuscular cells. Featured: Fiber Bundles Nodes

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages Gradient of heart automation Sinus node (in the left atrium) Bundles Fibers Atrioventricular node 40-50 30-40 10-20 decrease in the ability of automaticity in cells of the conduction system of the heart as they move away from the sinus node 60-80

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due to the blocking of venous and arterial passages. Thanks to impulses arising in the sinus node - the natural pacemaker, the heart contracts at a frequency of 60-80 times per minute. Every year, about 600,000 devices are installed in the world. When the heartbeat slows down, the patient is given an artificial pacemaker - an electric pacemaker. This is a medical device that generates electrical impulses at a given frequency and is designed to maintain heart rhythm.

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Work of the heart The heart, working as a pump, ensures constant blood circulation in the body. The contractile activity of the heart is associated with the work of the valves and the pressure in its cavities. Contraction of the heart muscle is called systole, and relaxation is called diastole. In 1 minute the heart pumps 6 liters of blood

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The valve, formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Phase 3 is a general pause of the heart. Flap valves are closed. The chambers of the heart are in diastole. From the veins, blood enters the atria. During this phase, the heart itself receives oxygen and nutrients. Phase 1 – atrial systole. Blood from the atria passes into the ventricles. Ventricular diastole. Phase 2 – ventricular systole. The blood pressure in the cavities of the ventricles increases; the leaflet valves slam shut under the pressure of blood; the semilunar valves open; blood from the right ventricle passes into the pulmonary arteries, and from the left into the aorta. Atrial diastole. RA LA RV LV Aorta Pulmonary arteries SVC IVC Pulmonary veins Cycle duration 0.8 s

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Blood vessels

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Blood vessels Arteries are vessels through which blood flows from the heart. Veins are vessels through which blood flows to the heart. Veins lie more superficially, almost parallel to the arteries. Capillaries located in the intercellular spaces

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Features of the structure of blood vessels Arteries Veins The capillary wall contains many muscle and elastic fibers. wall contain fewer muscle and elastic fibers. On the inner wall there are valves in the form of pockets that prevent the reverse flow of blood. do not have muscle or elastic fibers. The wall consists of a single layer of cells. 5mm 4mm 0.006mm valve

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Metabolism of substances and gases in capillaries. The capillary wall has pores through which the exchange of substances and gases occurs between blood and tissue cells. pores red blood cell

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Circulatory circles Blood in the body moves through a closed circulatory system, which consists of the systemic and pulmonary circulation.

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CO₂ O₂ CO₂ O₂ RV Pulmonary arteries Pulmonary capillaries 4 pulmonary veins LA Pulmonary circulation LV Aorta Arteries Organ capillaries Superior and inferior vena cava RA Systemic circulation

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages Lymphatic vessels

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Valve - formed by the folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages. Lymphatic vessels: are found in all parts of the body, with the exception of the central nervous system, bones, cartilage and teeth; pass next to arteries and veins.; collect excess fluid (lymph) from tissues; have valves that prevent lymph from flowing in the opposite direction.

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages BLOOD

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folds of its inner shell, ensures unidirectional blood flow by blocking the venous and arterial passages Deposited Circulating Facilitates the work of the heart Amount of blood 4-6 liters 40% Participate in maintaining a constant amount of circulating blood. 60%

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages 1. Transport (oxygen, carbon dioxide, metabolic products, hormones). 2. Regulatory (ensures the constancy of the internal environment of the body and maintains body temperature). 3. Protective (provides immunity and blood clotting). Blood functions

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages Blood is a liquid tissue consisting of plasma and blood cells suspended in it Plasma vessel Leukocytes Red blood cells Platelets 45% 55%

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages Blood plasma - water - proteins other substances: electrolytes, metabolic products 92% 7% 1%

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages Blood serum Blood plasma devoid of the fibrinogen protein is called blood serum. It is obtained by settling blood without an anticoagulant. Blood serum is used to treat most infectious diseases and poisonings.

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7-8 µm Erythrocytes red blood cells top view side view 7-8 µm They have the shape of biconcave discs. They don't have a core. 1 ml of blood contains 5 million red blood cells

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages. The lifespan of red blood cells is 3-4 months. Red blood cells are formed in the red bone marrow. 320 billion red blood cells are produced per day. Red blood cells are destroyed in the liver and spleen. Every second, from 2 to 10 million red blood cells are destroyed.

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages. Red blood cells contain hemoglobin Globin (protein part) Heme (non-protein part, contains an iron atom) Hemoglobin Red blood cell

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages. Functions of red blood cells Transfer of O₂ from the lungs to the cells of the body and CO₂ from the cells to the lungs. Artery Vein Capillary Red blood cell with O₂ Red blood cell with CO₂

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages Leukocytes white blood cells 1 ml of blood contains 4-8 thousand leukocytes leukocytes are not the same in structure and function; easily change shape and can penetrate the wall of a blood vessel to the location of a foreign body. 8-10 µm monocyte lymphocyte eosinophil basophil neutrophil leukopenia leukocytosis

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages. The lifespan of leukocytes is several days to 5 months. Leukocytes are formed: in the red bone marrow, lymph nodes, spleen, thymus Leukocytes are destroyed in the liver, spleen, in areas of inflammation

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folds of its inner membrane, ensures unidirectional blood flow by blocking the venous and arterial passages Functions of leukocytes Provide immunity Phagocytosis Production of antibodies

“Muscle work” - Leg muscles. The structure and function of skeletal muscles. Which letter represents smooth and striated muscles? Physical inactivity. Muscles of the torso at the back. Presentation for 8th grade Protsenko L.V. A-; B-. What is indicated by the numbers 1-; 2-; 3-; 4-. Basic concepts. Independent work: p. 69, Motor unit (MU).

"The Growth of Man" - Judgment Day: Friday, November 13, 2026. Coherence? Possible biological basis of the “Global Crisis”. H. von Foester. …”. I.S. Shklovsky, 1980. N = C / (2025-T) billions, where T is the current time, C is a constant (186 people*years). Nt = 186953/(38 - t). Biological basis of the “Global Crisis”.

“Analyzers” - Studying new material. XI. Temperature. What is the structure of the analyzer? XII. Teaching methods. VIII. Lesson plan. List the analyzers you know. "Brain Tentacles" Tactile.

“Internal environment of the body” - The internal environment of the body has a relative constancy of composition and physicochemical properties. Blood Lymph. The relationship between the components of the internal environment of the body. Tissue fluid. Internal environment of the body Tissue Blood Lymph (intercellular) fluid. Blood Plasma Formed elements: Blood platelets platelets Cells Erythrocytes Leukocytes.

“Bid structure” - Internodes. Opposite (ash, lilac, elderberry). A flower bud is the germ of a reproductive shoot. (Example: elderberry, lilac, willow). Knot. Oak. The structure of a vegetative shoot. Whorled (elodea). Selezneva Alena. Linden. Leaf mosaic. Internal structure of the kidney. Green leaves. Internal structure of a vegetative bud.

“Endocrine glands” - Hormones of the sex glands. ENDOCRINE SYSTEM. Glands of internal and mixed secretion. Thyroid. SIMULATOR 1. Pituitary gland 2. Adrenal glands 3. Thyroid gland 4. Pancreas 5. Sex glands. Municipal educational institution Kazachinskaya secondary school. Lesson plan. Lesson objectives. Insulin Adrenaline Thyroxine Norepinephrine Vasopressin Estradiol Testosterone Endorphin.

The heart has the shape of a cone, flattened in the anteroposterior direction. It distinguishes between the top and the base. The apex is the pointed part of the heart, directed down and to the left and slightly forward. The base is the expanded part of the heart, facing up and to the right and slightly back. It consists of strong elastic tissue - the heart muscle (myocardium), which contracts rhythmically throughout life, sending blood through the arteries and capillaries to the tissues of the body.

Structure of the Heart The HEART is a powerful muscular organ that pumps blood through a system of cavities (chambers) and valves into a closed distribution system called the circulatory system. The wall of the heart consists of three layers: the internal endocardium, the middle endocardium - the myocardium and the outer myocardium - the epicardium. epicardium

The endocardium lines the inside surface of the chambers of the heart; it is formed by a special type of epithelial tissue - endothelium. The endothelium has a very smooth, shiny surface, which reduces friction as blood moves through the heart. The myocardium makes up the bulk of the heart wall. It is formed by striated cardiac muscle tissue, the fibers of which, in turn, are arranged in several layers. The atrial myocardium is much thinner than the ventricular myocardium. The myocardium of the left ventricle is three times thicker than the myocardium of the right ventricle. The degree of development of the myocardium depends on the amount of work performed by the chambers of the heart. The myocardium of the atria and ventricles is separated by a layer of connective tissue (annulus fibrosus), which makes it possible to alternately contract the atria and ventricles. The epicardium is a special serous membrane of the heart, formed by connective and epithelial tissue.

Vessels of the circulatory system Arteries carry blood from the heart, and veins return blood to the heart. Between the arterial and venous sections of the circulatory system there is a microvasculature connecting them, including arterioles, venules, and capillaries. ARTERIES CAPILLARIES VEINS

ARTERIES The wall of the artery consists of three membranes: inner, middle and outer. The inner lining is the endothelium (squamous epithelium with a very smooth surface). The middle layer is formed by smooth muscle tissue and contains well-developed elastic fibers. Smooth muscle fibers change the lumen of the artery. Elastic fibers provide firmness, elasticity and strength to the walls of arteries. The outer shell consists of loose fibrous connective tissue, which plays a protective role and helps fix the arteries in a certain position. As they move away from the heart, the arteries branch strongly, eventually forming the smallest ones - arterioles.

Veins The second feature of veins is the large number of venous valves on the inner wall. They are arranged in pairs in the form of two semilunar folds. Venous valves prevent blood from flowing back in the veins when skeletal muscles work. There are no venous valves in the superior vena cava, pulmonary veins, veins of the brain and heart. The structure of the wall of veins is fundamentally the same as that of arteries. But the peculiarity is the significantly smaller wall thickness due to the thinness of the middle layer. It has much less muscle and elastic fibers due to low blood pressure in the veins.

Cardiac cycle. The sequence of contractions of the chambers of the heart is called the cardiac cycle. During the cycle, each of the four chambers goes through not only a contraction phase (systole), but also a relaxation phase (diastole). The atria contract first: first the right one, almost immediately followed by the left one. These contractions ensure that the relaxed ventricles are quickly filled with blood. Then the ventricles contract, forcefully pushing out the blood they contain. At this time, the atria relax and fill with blood from the veins. Each such cycle lasts on average 6/7 seconds.

Heart work in numbers In children and adults, the heart contracts at different frequencies: in children under one year of contractions per minute, at 10 years old 90, and at 20 years old and older 6070; after 60 years, the number of contractions becomes more frequent and reaches In athletes-runners, while running at sports competitions, the heart rate can reach up to 250 per minute; after running, the heart gradually calms down, and soon its normal rhythm of contractions is established. With each contraction, the heart throws out about 60–75 ml of blood, and per minute (with an average contraction frequency of 70 per minute) – 4–5 liters. Over 70 years, the heart produces more than 2.5 billion contractions and pumps approximately 156 million liters of blood. The work of the heart, like any other work, is measured by multiplying the weight of the lifted load (in kilograms) by the height (in meters). Let's try to determine its work. During the day, if a person does not do hard work, the heart contracts more than once; per year about once, and in 70 years of life almost once. What an impressive figure of three billion cuts! Now multiply the heart rate by the amount of blood ejected, and you will see what a huge amount of it it pumps. After making the calculation, you will be convinced that in an hour the heart pumps about 300 liters of blood, in a day over 7000 liters, in a year, and in 70 years of life liters. The blood pumped by the heart during a person's life can fill 4,375 railway tanks. If the heart pumped not blood, but water, then from the water it pumped over 70 years it would be possible to create a lake 2.5 m deep, 7 km wide and 10 km long. The work of the heart is very significant. So, with one beat, work is done with the help of which you can lift a load of 200 g to a height of 1 m. In 1 minute, the heart would lift this load 70 m, i.e. to the height of almost a twenty-story building. If it were possible to use the work of the heart, then in 8 hours it would be possible to lift a person to the height of the building of Moscow University (about 240 m), and in 3031 days to the top of Chomolungma, the highest point on the globe (8848 m)!

BLOOD PRESSURE The rhythmic work of the heart creates and maintains a pressure difference in the blood vessels. When the heart contracts, blood is forced into the arteries under pressure. During the passage of blood through the vessels, pressure energy is wasted. Therefore, blood pressure gradually decreases. In the aorta it is highest mm.Hg, in arteries – up to 120 mmHg, in capillaries up to 20, and in the vena cava from 3-8 mmHg. to minimum (-5) (below atmospheric). According to the law of physics, liquid moves from an area with higher pressure to an area with lower pressure. Arterial blood pressure is not a constant value. It pulsates in time with the contractions of the heart: at the moment of systole, the pressure rises to mmHg. (systolic pressure), and during diastole it decreases to mmHg. (diastolic). These pulse pressure fluctuations occur simultaneously with pulse fluctuations of the arterial wall. A person's blood pressure is measured. A person's blood pressure is measured in the brachial artery, comparing it with atmospheric pressure. A person's blood pressure is measured

HOW TO MEASURE BLOOD PRESSURE Air is pumped into the pressure gauge cuff until the pulse on the wrist disappears. Now the brachial artery is compressed by great external pressure and blood does not flow through it. Then, gradually releasing air from the cuff, watch for the appearance of a pulse. At this moment, the pressure in the artery becomes slightly greater than the pressure in the cuff, and the blood, and with it the pulse wave, begins to reach the wrist. The pressure gauge readings at this time will characterize the blood pressure in the brachial artery.

PULSE Pulse. When the ventricles contract, blood is ejected into the aorta, increasing its pressure. The wave that arises in its wall propagates at a certain speed from the aorta to the arteries. Rhythmic oscillations of the arterial wall. Caused by an increase in pressure in the aorta during systole, called the pulse. The pulse can be detected in places where large arteries come close to the surface of the body (wrist, temples, sides of the neck).