Where does the systemic circulation originate from? Circles of blood circulation. Complete Lessons - Knowledge Hypermarket

Small circle of blood circulation

Circles of blood circulation- this concept is conditional, since only in fish the circle of blood circulation is completely closed. In all other animals, the end of a large circle of blood circulation is the beginning of a small one and vice versa, which makes it impossible to speak of their complete isolation. In fact, both circles of blood circulation make up a single whole bloodstream, in two parts of which (right and left heart), kinetic energy is imparted to the blood.

circulatory circle- This is a vascular path that has its beginning and end in the heart.

Large (systemic) circulation

Structure

It begins with the left ventricle, which ejects blood into the aorta during systole. Numerous arteries depart from the aorta, as a result, the blood flow is distributed over several parallel regional vascular networks, each of which supplies blood to a separate organ. Further division of the arteries occurs into arterioles and capillaries. The total area of all capillaries in the human body is approximately 1000 m².

After passing through the organ, the process of fusion of capillaries into venules begins, which in turn gather into veins. Two vena cava approach the heart: the upper and lower, which, when merged, form part of the right atrium of the heart, which is the end of the systemic circulation. The circulation of blood in the systemic circulation occurs in 24 seconds.

Exceptions in structure

Circulation of the spleen and intestines. The general structure does not include blood circulation in the intestines and spleen, since after the formation of the splenic and intestinal veins, they merge to form the portal vein. The portal vein re-disintegrates in the liver into a capillary network, and only after that the blood enters the heart.
Kidney circulation. In the kidney, there are also two capillary networks - the arteries break up into the Shumlyansky-Bowman capsules that bring arterioles, each of which breaks up into capillaries and collects into the efferent arteriole. The efferent arteriole reaches the convoluted tubule of the nephron and re-disintegrates into a capillary network.

Functions

Blood supply to all organs of the human body, including the lungs.

Small (pulmonary) circulation

Structure

It begins in the right ventricle, which ejects blood into the pulmonary trunk. The pulmonary trunk divides into the right and left pulmonary arteries. Arteries are dichotomously divided into lobar, segmental and subsegmental arteries. Subsegmental arteries divide into arterioles, which break up into capillaries. The outflow of blood goes through the veins, going in the reverse order, which in the amount of 4 pieces flow into the left atrium. The circulation of blood in the pulmonary circulation occurs in 4 seconds.

The pulmonary circulation was first described by Miguel Servet in the 16th century in the book Restoration of Christianity.

Functions

Heat dissipation

Small circle function is not nourishment of the lung tissue.

"Additional" circles of blood circulation

Depending on the physiological state of the body, as well as practical expediency, additional circles of blood circulation are sometimes distinguished:

placental,
cordial.

Placental circulation

It exists in the fetus in the uterus.

Blood that is not fully oxygenated leaves through the umbilical vein, which runs in the umbilical cord. From here, most of the blood flows through the ductus venosus into the inferior vena cava, mixing with unoxygenated blood from the lower body. A smaller portion of blood enters the left branch of the portal vein, passes through the liver and hepatic veins, and enters the inferior vena cava.

Mixed blood flows through the inferior vena cava, the saturation of which with oxygen is about 60%. Almost all of this blood flows through the foramen ovale in the wall of the right atrium into the left atrium. From the left ventricle, blood is ejected into the systemic circulation.

Blood from the superior vena cava first enters the right ventricle and pulmonary trunk. Since the lungs are in a collapsed state, the pressure in the pulmonary arteries is greater than in the aorta, and almost all the blood passes through the arterial (Botallov) duct into the aorta. The arterial duct flows into the aorta after the arteries of the head and upper limbs leave it, which provides them with more enriched blood. A very small amount of blood enters the lungs, which then enters the left atrium.

Part of the blood (~60%) from the systemic circulation enters the placenta through two umbilical arteries; the rest - to the organs of the lower body.

Cardiac circulation or coronary circulation

Structurally, it is part of the systemic circulation, but due to the importance of the organ and its blood supply, this circle can sometimes be found in the literature.

Arterial blood flows to the heart through the right and left coronary arteries. They begin at the aorta above its semilunar valves. Smaller branches depart from them, which enter the muscle wall and branch to the capillaries. The outflow of venous blood occurs in 3 veins: large, medium, small, vein of the heart. Merging, they form the coronary sinus and it opens into the right atrium.

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The human body is permeated with vessels through which blood circulates continuously. This is an important condition for the life of tissues and organs. The movement of blood through the vessels depends on nervous regulation and is provided by the heart, which acts as a pump.

The structure of the circulatory system

The circulatory system includes:

veins;
arteries;
capillaries.

The liquid constantly circulates in two closed circles. Small supplies the vascular tubes of the brain, neck, upper body. Large - vessels of the lower body, legs. In addition, there are placental (available during fetal development) and coronary circulation.

The structure of the heart

The heart is a hollow cone made up of muscle tissue. In all people, the body is slightly different in shape, sometimes in structure.. It has 4 departments - the right ventricle (RV), the left ventricle (LV), the right atrium (RA) and the left atrium (LA), which communicate with each other by openings.

The holes are covered with valves. Between the left sections - the mitral valve, between the right - tricuspid.

The pancreas pushes fluid into the pulmonary circulation - through the pulmonary valve to the pulmonary trunk. The LV has denser walls, as it pushes blood to the systemic circulation, through the aortic valve, that is, it must create sufficient pressure.

After a portion of the liquid is ejected from the department, the valve is closed, which ensures the movement of the liquid in one direction.

Functions of the arteries

The arteries supply oxygenated blood. Through them, it is transported to all tissues and internal organs. The walls of the vessels are thick and highly elastic. Fluid is ejected into the artery under high pressure - 110 mm Hg. Art., and elasticity is a vital quality that keeps the vascular tubes intact.

The artery has three sheaths that ensure its ability to perform its functions. The middle shell consists of smooth muscle tissue, which allows the walls to change the lumen depending on body temperature, the needs of individual tissues, or under high pressure. Penetrating into the tissues, the arteries narrow, passing into the capillaries.

Functions of capillaries

Capillaries penetrate all tissues of the body, except for the cornea and epidermis, carry oxygen and nutrients to them. The exchange is possible due to the very thin wall of the vessels. Their diameter does not exceed the thickness of the hair. Gradually, the arterial capillaries pass into the venous ones.

Functions of the veins

Veins carry blood to the heart. They are larger than arteries and contain about 70% of the total blood volume. Along the course of the venous system there are valves that work on the principle of the heart. They allow blood to pass through and close behind it to prevent its outflow. Veins are divided into superficial, located directly under the skin, and deep - passing in the muscles.

The main task of the veins is to transport blood to the heart, in which there is no longer oxygen and decay products are present. Only the pulmonary veins carry oxygenated blood to the heart. There is an upward movement. In case of violation of the normal operation of the valves, the blood stagnates in the vessels, stretching them and deforming the walls.

What are the reasons for the movement of blood in the vessels:

myocardial contraction;
contraction of the smooth muscle layer of blood vessels;
difference in blood pressure between arteries and veins.

The movement of blood through the vessels

Blood moves through the vessels continuously. Somewhere faster, somewhere slower, it depends on the diameter of the vessel and the pressure under which blood is ejected from the heart. The speed of movement through the capillaries is very low, due to which metabolic processes are possible.

The blood moves in a vortex, bringing oxygen along the entire diameter of the vessel wall. Due to such movements, oxygen bubbles seem to be pushed out of the boundaries of the vascular tube.

The blood of a healthy person flows in one direction, the outflow volume is always equal to the inflow volume. The reason for the continuous movement is due to the elasticity of the vascular tubes and the resistance that the fluid has to overcome. When blood enters, the aorta with the artery stretches, then narrows, gradually passing fluid further. Thus, it does not move in jerks, as the heart contracts.

Small circle of blood circulation

The small circle diagram is shown below. Where, RV — right ventricle, LS — pulmonary trunk, RLA — right pulmonary artery, LLA — left pulmonary artery, LV — pulmonary veins, LA — left atrium.

Through the pulmonary circulation, the fluid passes to the pulmonary capillaries, where it receives oxygen bubbles. The oxygenated fluid is called arterial. From the LP, it passes to the LV, where the bodily circulation originates.

Systemic circulation

Scheme of the corporal circle of blood circulation, where: 1. Left - left ventricle.

2. Ao - aorta.

3. Art - arteries of the trunk and limbs.

4. B - veins.

5. PV - vena cava (right and left).

6. PP - right atrium.

The bodily circle is aimed at spreading a liquid full of oxygen bubbles throughout the body. It carries O 2 , nutrients to the tissues, collecting decay products and CO 2 along the way. After that, there is a movement along the route: PZH - LP. And then it starts again through the pulmonary circulation.

Personal circulation of the heart

The heart is an "autonomous republic" of the body. It has its own system of innervation, which sets the muscles of the organ in motion. And its own circle of blood circulation, which is made up of coronary arteries with veins. The coronary arteries independently regulate the blood supply to the heart tissues, which is important for the continuous functioning of the organ.

The structure of the vascular tubes is not identical. Most people have two coronary arteries, but there is a third. The heart can be fed from the right or left coronary artery. Because of this, it is difficult to establish the norms of cardiac circulation. depends on the load, physical fitness, age of the person.

Placental circulation

Placental circulation is inherent in every person at the stage of fetal development. The fetus receives blood from the mother through the placenta, which forms after conception. From the placenta, it moves to the umbilical vein of the child, from where it goes to the liver. This explains the large size of the latter.

The arterial fluid enters the vena cava, where it mixes with the venous fluid, then goes to the left atrium. From it, blood flows to the left ventricle through a special hole, after which it goes directly to the aorta.

The movement of blood in the human body in a small circle begins only after birth. With the first breath, the vessels of the lungs expand, and they develop for a couple of days. The oval hole in the heart can persist for a year.

Circulatory pathologies

Blood circulation is carried out in a closed system. Changes and pathologies in the capillaries can adversely affect the functioning of the heart. Gradually, the problem will worsen and develop into a serious disease. Factors affecting the movement of blood:

Pathologies of the heart and large vessels lead to the fact that the blood flows to the periphery in insufficient volume. Toxins stagnate in the tissues, they do not receive proper oxygen supply and gradually begin to break down.
Blood pathologies such as thrombosis, stasis, embolism lead to blockage of blood vessels. Movement through the arteries and veins becomes difficult, which deforms the walls of blood vessels and slows down the flow of blood.
vascular deformity. The walls can become thinner, stretch, change their permeability and lose elasticity.
Hormonal pathologies. Hormones are able to increase blood flow, which leads to a strong filling of blood vessels.
Compression of blood vessels. When the blood vessels are compressed, the blood supply to the tissues stops, which leads to cell death.
Violations of the innervation of organs and injuries can lead to the destruction of the walls of arterioles and provoke bleeding. Also, a violation of normal innervation leads to a disorder of the entire circulatory system.
Infectious diseases of the heart. For example, endocarditis, in which the valves of the heart are affected. The valves do not close tightly, which contributes to the backflow of blood.
Damage to the vessels of the brain.
Diseases of the veins in which the valves are affected.

Also, the way of life of a person affects the movement of blood. Athletes have a more stable circulatory system, so they are more enduring and even fast running will not immediately speed up the heart rate.

The average person can undergo changes in blood circulation even from smoking a cigarette. With injuries and ruptures of blood vessels, the circulatory system is able to create new anastomoses in order to provide blood to the "lost" areas.

Regulation of blood circulation

Any process in the body is controlled. There is also regulation of blood circulation. The activity of the heart is activated by two pairs of nerves - sympathetic and vagus. The first excite the heart, the second slow down, as if controlling each other. Severe stimulation of the vagus nerve can stop the heart.

A change in the diameter of the vessels also occurs due to nerve impulses from the medulla oblongata. The heart rate increases or decreases depending on signals received from external irritation, such as pain, temperature changes, etc.

In addition, the regulation of cardiac work occurs due to substances contained in the blood. For example, adrenaline increases the frequency of myocardial contractions and at the same time constricts blood vessels. Acetylcholine has the opposite effect.

All these mechanisms are needed to maintain constant uninterrupted work in the body, regardless of changes in the external environment.

The cardiovascular system

The above is only a brief description of the human circulatory system. The body contains a huge number of blood vessels. The movement of blood in a large circle passes throughout the body, providing blood to every organ.

The cardiovascular system also includes the organs of the lymphatic system. This mechanism works in concert, under the control of neuro-reflex regulation. The type of movement in the vessels can be direct, which excludes the possibility of metabolic processes, or vortex.

The movement of blood depends on the work of each system in the human body and cannot be described by a constant value. It varies depending on many external and internal factors. For different organisms that exist in different conditions, there are their own norms of blood circulation, under which normal life will not be in danger.

Lesson Objectives

Explain the concept of blood circulation, the causes of blood movement.

Features of the structure of the circulatory organs in connection with their functions, to consolidate students' knowledge of the large and small circles of blood circulation.

Lesson objectives

generalization and deepening of knowledge on the topic “Circulation of blood circulation”
activating the attention of students on the structural features of the circulatory organs
implementation of the practical application of existing knowledge, skills and abilities (work with tables, reference materials)
development of students' cognitive interest in subjects of the natural cycle
development of mental operations of analysis, synthesis
formation of reflective qualities (introspection, self-correction)
development of communication skills
creating a psychologically comfortable environment

Basic terms

Circulation - the movement of blood through the circulatory system, providing metabolism.
Heart (from Greek ἀνα- - again, from above and τέμνω - “I cut”, “cut”) - the central organ of the circulatory system, the contractions of which circulate blood through the vessels
Valves:

tricuspid (between the right atrium and the right ventricle), pulmonary valve, bicuspid (mitral) between the left atrium and the left ventricle of the heart, aortic valve.

arteries (lat. arteria) - vessels that carry blood from the heart.

Vienna - Vessels that carry blood to the heart.
capillaries (from lat. capillaris - hair) - microscopic vessels that are in tissues and connect arterioles with veins, carry out the exchange of substances between blood and tissues.

Homework repetition

Testing students' knowledge

Subjects > Biology > Biology Grade 8

A person has a closed circulatory system, the central place in it is occupied by a four-chambered heart. Regardless of the composition of the blood, all vessels that come to the heart are considered to be veins, and those leaving it are considered arteries. The blood in the human body moves through the large, small and cardiac circles of blood circulation.

Small circle of blood circulation (pulmonary). Venous blood from the right atrium through the right atrioventricular opening passes into the right ventricle, which, contracting, pushes the blood into the pulmonary trunk. The latter is divided into the right and left pulmonary arteries passing through the gates of the lungs. In the lung tissue, the arteries divide into capillaries surrounding each alveolus. After the erythrocytes release carbon dioxide and enrich them with oxygen, venous blood turns into arterial blood. Arterial blood through four pulmonary veins (two veins in each lung) is collected in the left atrium, and then through the left atrioventricular opening passes into the left ventricle. The systemic circulation begins from the left ventricle.

Systemic circulation. Arterial blood from the left ventricle during its contraction is ejected into the aorta. The aorta splits into arteries that supply blood to the head, neck, limbs, torso and all internal organs, in which they end in capillaries. Nutrients, water, salts and oxygen are released from the blood of capillaries into the tissues, metabolic products and carbon dioxide are resorbed. Capillaries gather into venules, where the venous vascular system begins, representing the roots of the superior and inferior vena cava. Venous blood through these veins enters the right atrium, where the systemic circulation ends.

Cardiac circulation. This circle of blood circulation begins from the aorta with two coronary cardiac arteries, through which blood enters all layers and parts of the heart, and then is collected through small veins into the coronary sinus. This vessel with a wide mouth opens into the right atrium of the heart. Part of the small veins of the heart wall opens into the cavity of the right atrium and ventricle of the heart independently.

Thus, only after passing through the pulmonary circulation, blood enters the large circle, and it moves through a closed system. The speed of the blood circulation in a small circle is 4-5 seconds, in a large one - 22 seconds.

Criteria for assessing the activity of the cardiovascular system.

To assess the work of the CCC, its following characteristics are examined - pressure, pulse, electrical work of the heart.

ECG. Electrical phenomena observed in tissues during excitation are called action currents. They also occur in the beating heart, since the excited area becomes electronegative with respect to the unexcited one. You can register them using an electrocardiograph.

Our body is a liquid conductor, i.e., a conductor of the second kind, the so-called ionic one, therefore the biocurrents of the heart are conducted throughout the body and they can be recorded from the surface of the skin. In order not to interfere with the currents of the action of skeletal muscles, a person is laid on a couch, asked to lie still and electrodes are applied.

To register three standard bipolar leads from the extremities, electrodes are applied to the skin of the right and left hands - I lead, the right hand and left leg - II lead and the left hand and left leg - III lead.

When registering thoracic (pericardial) unipolar leads, denoted by the letter V, one electrode, which is inactive (indifferent), is applied to the skin of the left leg, and the second - active - to certain points of the anterior surface of the chest (V1, V2, V3, V4, v5, V6). These leads help to determine the localization of damage to the heart muscle. The recording curve of the biocurrents of the heart is called an electrocardiogram (ECG). The ECG of a healthy person has five teeth: P, Q, R, S, T. The P, R and T waves, as a rule, are directed upwards (positive teeth), Q and S - down (negative teeth). The P wave reflects atrial excitation. At the time when the excitation reaches the muscles of the ventricles and spreads through them, a QRS wave occurs. The T wave reflects the process of termination of excitation (repolarization) in the ventricles. Thus, the P wave makes up the atrial part of the ECG, and the Q, R, S, T wave complex makes up the ventricular part.

Electrocardiography makes it possible to study in detail changes in the heart rhythm, impaired conduction of excitation through the conduction system of the heart, the occurrence of an additional focus of excitation when extrasystoles appear, ischemia, heart attack.

Blood pressure. The value of blood pressure is an important characteristic of the activity of the cardiovascular system. An indispensable condition for the movement of blood through the system of blood vessels is the difference in blood pressure in the arteries and veins, which is created and maintained by the heart. With each systole of the heart, a certain volume of blood is pumped into the arteries. Due to the high resistance in the arterioles and capillaries, until the next systole, only part of the blood has time to pass into the veins and the pressure in the arteries does not drop to zero.

The level of pressure in the arteries should be determined by the value of the systolic volume of the heart and the resistance in the peripheral vessels: the more forcefully the heart contracts and the more narrowed the arterioles and capillaries, the higher the blood pressure. In addition to these two factors: the work of the heart and peripheral resistance, blood pressure is affected by the volume of circulating blood and its viscosity.

The highest pressure observed during systole is called the maximum, or systolic, pressure. The lowest pressure during diastole is called minimum, or diastolic. The amount of pressure depends on age. In children, the walls of the arteries are more elastic, so their pressure is lower than in adults. In healthy adults, the maximum pressure is normally 110 - 120 mm Hg. Art., and the minimum 70 - 80 mm Hg. Art. By old age, when the elasticity of the vascular walls decreases as a result of sclerotic changes, the level of blood pressure rises.

The difference between the maximum and minimum pressure is called pulse pressure. It is equal to 40 - 50 mm Hg. Art.

The value of blood pressure can be measured by two methods - direct and indirect. When measuring in a direct, or bloody, way, a glass cannula is tied into the central end of the artery or a hollow needle is inserted, which is connected with a rubber tube to a measuring device, such as a mercury manometer. In a direct way, a person’s pressure is recorded during major operations, for example, on the heart, when pressure must be continuously monitored.

To determine the pressure by an indirect, or indirect, method, the external pressure is found that is sufficient to occlude the artery. In medical practice, blood pressure in the brachial artery is usually measured by the Korotkoff indirect sound method using a Riva-Rocci mercury sphygmomanometer or a spring tonometer. A hollow rubber cuff is placed on the shoulder, which is connected to an injection rubber bulb and a pressure gauge showing the pressure in the cuff. When air is forced into the cuff, it presses on the tissues of the shoulder and compresses the brachial artery, and the pressure gauge shows the value of this pressure. Vascular tones are heard with a phonendoscope above the ulnar artery, below the cuff. S. Korotkov found that in an uncompressed artery there are no sounds during the movement of blood. If you raise the pressure above the systolic level, then the cuff completely occludes the lumen of the artery and the blood flow in it stops. There are also no sounds. If now we gradually release air from the cuff and reduce the pressure in it, then at the moment when it becomes slightly lower than systolic, the blood during systole will break through the squeezed area with great force and below the cuff in the ulnar artery a vascular tone will be heard. The pressure in the cuff at which the first vascular sounds appear corresponds to the maximum, or systolic, pressure. With further release of air from the cuff, i.e., a decrease in pressure in it, the tones increase, and then either sharply weaken or disappear. This moment corresponds to diastolic pressure.

Pulse. The pulse is called the rhythmic fluctuations in the diameter of arterial vessels that occur during the work of the heart. At the moment of expulsion of blood from the heart, the pressure in the aorta rises, and a wave of increased pressure propagates along the arteries to the capillaries. It is easy to feel the pulsation of the arteries that lie on the bone (radial, superficial temporal, dorsal artery of the foot, etc.). Most often examine the pulse on the radial artery. Feeling and counting the pulse, you can determine the heart rate, their strength, as well as the degree of elasticity of the vessels. An experienced doctor, by pressing on the artery until the pulsation stops completely, can quite accurately determine the height of blood pressure. In a healthy person, the pulse is rhythmic, i.e. strikes follow at regular intervals. In diseases of the heart, rhythm disturbances - arrhythmia - can be observed. In addition, such characteristics of the pulse as tension (pressure in the vessels), filling (amount of blood in the bloodstream) are also taken into account.

In our body blood continuously moves along a closed system of vessels in a strictly defined direction. This continuous movement of blood is called blood circulation. Circulatory system a person is closed and has 2 circles of blood circulation: large and small. The main organ that ensures the movement of blood is the heart.

The circulatory system is made up of hearts and vessels. Vessels are of three types: arteries, veins, capillaries.

Heart- a hollow muscular organ (weighing about 300 grams) about the size of a fist, located in the chest cavity on the left. The heart is surrounded by a pericardial sac formed by connective tissue. Between the heart and the pericardial sac is a fluid that reduces friction. Humans have a four-chambered heart. The transverse septum divides it into left and right halves, each of which is separated by valves neither an atrium and a ventricle. The walls of the atria are thinner than the walls of the ventricles. The walls of the left ventricle are thicker than the walls of the right ventricle, as it does a lot of work, pushing blood into the systemic circulation. At the border between the atria and ventricles, there are cuspid valves that prevent the backflow of blood.

The heart is surrounded by a pericardial sac (pericardium). The left atrium is separated from the left ventricle by a bicuspid valve, and the right atrium is separated from the right ventricle by a tricuspid valve.

Strong tendon filaments are attached to the valve leaflets from the side of the ventricles. Their design does not allow blood to move from the ventricles to the atrium during the contraction of the ventricle. At the base of the pulmonary artery and aorta are the semilunar valves, which prevent blood from flowing back from the arteries back into the ventricles.

The right atrium receives venous blood from the systemic circulation, while the left atrium receives arterial blood from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, to the left - arterial from the lungs. Since the left ventricle supplies blood to all organs of the systemic circulation, its walls are about three times thicker than the walls of the right ventricle. The cardiac muscle is a special type of striated muscle in which the muscle fibers grow together at the ends and form a complex network. This structure of the muscle increases its strength and accelerates the passage of the nerve impulse (the entire muscle reacts simultaneously). Cardiac muscle differs from skeletal muscles in its ability to contract rhythmically in response to impulses originating in the heart itself. This phenomenon is called automation.

arteries Vessels that carry blood away from the heart. Arteries are thick-walled vessels, the middle layer of which is represented by elastic and smooth muscles, so the arteries are able to withstand significant blood pressure and not rupture, but only stretch.

The smooth muscles of the arteries perform not only a structural role, but its contractions contribute to the fastest blood flow, since the power of only one heart would not be enough for normal blood circulation. There are no valves inside the arteries, the blood flows quickly.

Vienna- Vessels that carry blood to the heart. The walls of the veins also have valves that prevent backflow of blood.

Veins are thinner-walled than arteries and have fewer elastic fibers and muscle elements in the middle layer.

The blood through the veins does not flow completely passively, the surrounding muscles make pulsating movements and drive the blood through the vessels to the heart. Capillaries are the smallest blood vessels, through which blood plasma exchanges nutrients with tissue fluid. The capillary wall consists of a single layer of flat cells. The membranes of these cells have multi-membered tiny holes that facilitate the passage of substances involved in the exchange through the capillary wall.

Blood movement occurs in two circles of blood circulation.

Systemic circulation- this is the path of blood from the left ventricle to the right atrium: left ventricle aorta thoracic aorta abdominal aorta arteries capillaries in organs (gas exchange in tissues) veins superior (inferior) vena cava right atrium

Small circle of blood circulation- the path from the right ventricle to the left atrium: right ventricle pulmonary trunk artery right (left) pulmonary capillaries in the lungs gas exchange in the lungs pulmonary veins left atrium

In the pulmonary circulation, venous blood moves through the pulmonary arteries, and arterial blood moves through the pulmonary veins after gas exchange in the lungs.