Arteries - blood vessels, going from the heart to the organs and carrying blood to them, are called arteries (aeg - air, tereo - contain; on corpses the arteries are empty, which is why in the old days they were considered air tubes).
The wall of the arteries consists of three membranes. Inner shell, tunica intima, lined on the side of the lumen of the vessel with endothelium, under which lie the subendothelium and internal elastic membrane; middle, tunica media, built from fibers of non-striated muscle tissue, myocytes, alternating with elastic fibers; outer shell, tunica externa, contains connective woven fibers.
The elastic elements of the arterial wall form a single elastic frame that works like a spring and determines the elasticity of the arteries. As they move away from the heart, the arteries divide into branches and become smaller and smaller.
The arteries closest to the heart (the aorta and its large branches) primarily perform the function of conducting blood. In them, counteraction to stretching by the mass of blood, which is ejected by the heart impulse, comes to the fore. Therefore, structures of a mechanical nature, i.e., elastic fibers and membranes, are relatively more developed in their walls. Such arteries are called elastic arteries.
In medium and small arteries, in which the inertia of the cardiac impulse weakens and the own contraction of the vascular wall is required for further movement of blood, the contractile function predominates. It is ensured by a relatively large development of muscle tissue in the vascular wall. Such arteries are called muscular arteries. Individual arteries supply blood to entire organs or parts thereof.
In relation to an organ, there are arteries that go outside the organ, before entering it - extraorgan arteries, and their continuations that branch inside it - intraorgan, or itpraorgan, arteries. Lateral branches of the same trunk or branches of different trunks can connect to each other. This connection of vessels before they break up into capillaries is called anastomosis, or anastomosis (stoma - mouth). The arteries that form anastomoses are called anastomosing (they are the majority).
Arteries that do not have anastomoses with neighboring trunks before they become capillaries are called terminal arteries (for example, in the spleen). Terminal, or terminal, arteries are more easily blocked by a blood plug (thrombus) and predispose to the formation of a heart attack (local death of the organ). The last branches of the arteries become thin and small and are therefore called arterioles. An arteriole differs from an artery in that its wall has only one layer of muscle cells, thanks to which it carries out a regulatory function. The arteriole continues directly into the precapillary, in which muscle cells scattered and do not form a continuous layer. The precapillary also differs from the arteriole in that it is not accompanied by a venule. Numerous capillaries extend from the precapillary.
Development of arteries. Reflecting the transition in the process of phylogenesis from the gill circulation to the pulmonary circulation, in humans, in the process of ontogenesis, the aortic arches are first formed, which are then transformed into the arteries of the pulmonary and body circulation. In a 3-week-old embryo, the truncus arteriosus, emerging from the heart, gives rise to two arterial trunks, called the ventral aortas (right and left). The ventral aortas go in an ascending direction, then turn back to the dorsal side of the embryo; here they, passing on the sides of the chord, go in a descending direction and are called dorsal aortas. The dorsal aortas gradually move closer to each other and in the middle section of the embryo merge into one unpaired descending aorta. As the branchial arches develop at the head end of the embryo, the so-called aortic arch, or artery, is formed in each of them; these arteries connect the ventral and dorsal aortas on each side.
Thus, in the region of the branchial arches, the ventral (ascending) and dorsal (descending) aortas are connected to each other using 6 pairs of aortic arches. Subsequently, part of the aortic arches and part of the dorsal aortas, especially the right one, are reduced, and from the remaining primary vessels large pericardial and main arteries develop, namely: truncus arteriosus, as noted above, is divided by the frontal septum into the ventral part, from which the pulmonary trunk is formed, and dorsal, which turns into the ascending aorta. This explains the location of the aorta behind the pulmonary trunk.
It should be noted that the last pair of aortic arches along the blood flow, which in lungfishes and amphibians acquires a connection with the lungs, also turns into two pulmonary arteries in humans - the right and left, branches of the truncus pulmonalis. Moreover, if the right sixth aortic arch is preserved only on a small proximal segment, then the left one remains along its entire length, forming a ductus arteriosus, which connects the pulmonary trunk with the end of the aortic arch, which is important for the blood circulation of the fetus. The fourth pair of aortic arches is preserved on both sides throughout its entire length, but gives rise to various vessels. The left 4th aortic arch, together with the left ventral aorta and part of the left dorsal aorta, form the aortic arch, arcus aortae. The proximal segment of the right ventral aorta turns into the brachiocephalic trunk, truncus blachiocephalicus, the right 4th aortic arch turns into the beginning of the right subclavian artery, a. subclavia dextra. The left subclavian artery arises from the left dorsal aorta caudal to the last aortic arch.
The dorsal aortas in the area between the 3rd and 4th aortic arches are obliterated; in addition, the right dorsal aorta is also obliterated from the origin of the right subclavian artery to its confluence with the left dorsal aorta. Both ventral aortas in the area between the fourth and third aortic arches are transformed into the common carotid arteries, aa. carotides communes, and due to the above transformations of the proximal ventral aorta, the right common carotid artery turns out to arise from the brachiocephalic trunk, and the left one - directly from the arcus aortae. Further along the ventral aortas turn into the external carotid arteries, aa. carotides externae. The third pair of aortic arches and the dorsal aortas in the segment from the third to the first branchial arch develop into the internal carotid arteries, aa. carotides internae, which explains that the internal carotid arteries lie more laterally in adults than the external ones. The second pair of aortic arches turns into aa. linguales et pharyngeae, and the first pair - into the maxillary, facial and temporal arteries. When the normal course of development is disrupted, various anomalies occur.
From the dorsal aortas arise a series of small paired vessels running dorsally on both sides of the neural tube. Because these vessels extend at regular intervals into the loose mesenchymal tissue located between the somites, they are called dorsal intersegmental arteries. In the neck area, they are early connected on both sides of the body by a series of anastomoses, forming longitudinal vessels - the vertebral arteries. At the level of the 6th, 7th and 8th cervical intersegmental arteries, the kidneys of the upper extremities are formed. One of the arteries, usually the 7th, grows into the upper limb and increases with the development of the arm, forming the distal section of the subclavian artery (its proximal section develops, as already indicated, on the right from the 4th aortic arch, on the left it grows from the left dorsal aorta, with with which the 7th intersegmental arteries are connected). Subsequently, the cervical intersegmental arteries are obliterated, as a result of which the vertebral arteries appear to arise from the subclavian ones. The thoracic and lumbar intersegmental arteries give rise to the aa. intercostales posteriores and aa. lumbales.
Visceral arteries abdominal cavity develop partly from aa. omphalomesentericae (yolk-mesenteric circulation) and partly from the aorta. The arteries of the limbs are initially laid along the nerve trunks in the form of loops. Some of these loops (along the n. femoralis) develop into the main arteries of the limbs, others (along the n. medianus, n. ischiadicus) remain companions of the nerves.
Which doctors should I contact to examine the Arteries:
Cardiologist
Cardiac surgeon
Heart - most important organ to maintain life human body. Through its rhythmic contractions, it distributes blood throughout the body, providing nutrition to all elements.
The coronary arteries are responsible for saturating the heart with oxygen.. Another common name for them is coronary vessels.
Cyclic repetition of this process ensures uninterrupted blood supply, which keeps the heart in working condition.
Coronaries are a whole group of vessels that supply blood to the heart muscle (myocardium). They carry oxygen-rich blood to all parts of the heart.
The outflow of (venous) blood depleted of its content is carried out by 2/3 of the large, middle and small veins, which are woven into a single vast vessel - the coronary sinus. The remainder is excreted by the anterior and basal veins.
When the heart ventricles contract, the shutter seals off the arterial valve. The coronary artery at this moment is almost completely blocked and blood circulation in this area stops.
The flow of blood is resumed after the opening of the entrances to the arteries. Filling of the aortic sinuses occurs due to the impossibility of blood returning to the cavity of the left ventricle after its relaxation, because at this time the dampers close.
Important! The coronary arteries are the only possible source of blood supply for the myocardium, so any violation of their integrity or operating mechanism is very dangerous.
Scheme of the structure of coronary vessels
The structure of the coronary network has a branched structure: several large branches and many smaller ones.
The arterial branches originate from the aortic bulb, immediately after the aortic valve valve and, bending around the surface of the heart, supply blood to its different parts.
These heart vessels consist of three layers:
- Initial – endothelium;
- Muscle fibrous layer;
- Adventitia.
This multi-layering makes the walls of blood vessels very elastic and durable.. This promotes proper blood flow even under conditions of high stress on the cardiovascular system, including intense sports, which increase the speed of blood movement up to five times.
Types of coronary arteries
All vessels that make up a single arterial network, based on the anatomical details of their location, are divided into:
- Basic (epicardial)
- Subordinate (remaining branches):
- Right coronary artery. Its main responsibility is to nourish the right heart ventricle. Partially supplies oxygen to the wall of the left cardiac ventricle and the common septum.
- Left coronary artery. Provides blood flow to all other parts of the heart. It is a branching into several parts, the number of which depends on the personal characteristics of a particular organism.
- Enveloping branch. It is a branch from the left side and supplies the septum of the corresponding ventricle. It is subject to increased thinning in the presence of the slightest damage.
- Anterior descending(major interventricular) branch. It also comes from the left artery. Forms the basis for admission nutrients for the heart and the septum between the ventricles.
- Subendocardial arteries. They are considered part of the general coronary system, but pass deep into the heart muscle (myocardium), and not on the surface itself.
All arteries are located directly on the surface of the heart itself (except for the subendocardial vessels). Their work is regulated by their own internal processes, which also control the exact volume of blood supplied to the myocardium. Options for dominant blood supply
The dominant arteries supplying the posterior descending branch of the artery, which can be either right or left.
Define general type blood supply to the heart:
- The right blood supply is dominant if this branch arises from the corresponding vessel;
- The left type of power supply is possible if posterior artery– this is a branch from the circumflex vessel;
- Blood flow can be considered balanced if it comes simultaneously from the right trunk and from the left circumflex branch coronary artery.
Reference. The predominant source of nutrition is determined based on the total flow of blood flow to the atrioventricular node.
In the vast majority of cases (about 70%), a person has a dominant right blood supply. Equal work of both arteries is present in 20% of people. Left dominant nutrition through the blood appears only in the remaining 10% of cases.
What is coronary heart disease?
Coronary heart disease (CHD), also called coronary artery disease (CHD), is any disease associated with sharp deterioration blood supply to the heart due to insufficient activity of the coronary system.
IHD can have both an acute and chronic form. Most often it manifests itself against the background of atherosclerosis of the arteries, which occurs due to general thinning or disruption of the integrity of the vessel.
A plaque forms at the site of damage, which gradually increases in size, narrows the lumen and thereby interferes with the normal flow of blood.
The list of coronary diseases includes:
- Angina;
- Arrhythmia;
- Embolism;
- Arteritis;
- Heart attack;
- Distortion of the coronary arteries;
- Death due to cardiac arrest.
For coronary disease characterized by wave-like jumps in the general condition, in which the chronic phase rapidly turns into acute phase and vice versa.
How are pathologies determined?
Coronary diseases manifest themselves as severe pathologies, initial form which is angina pectoris. Subsequently, it develops into more serious diseases and the onset of attacks no longer requires strong nervous or physical stress.
Angina pectoris
Scheme of changes in the coronary artery In everyday life, such a manifestation of IHD is sometimes called a “toad on the chest.” This is due to the occurrence of attacks of suffocation, which are accompanied by pain.
Initially, symptoms make themselves felt in the chest area, after which they spread to left side back, shoulder blade, collarbone and lower jaw (rarely).
Painful sensations are the result of oxygen starvation of the myocardium, which is aggravated during physical, mental work, anxiety or overeating.
Myocardial infarction
Cardiac infarction is a very serious condition accompanied by the death of individual parts of the myocardium (necrosis). This occurs due to a complete cessation or incomplete flow of blood into the organ, which most often occurs against the background of the formation of a blood clot in the coronary vessels.
Blocked coronary artery - Acute chest pain that radiates to neighboring areas;
- Heaviness, difficulty breathing;
- Trembling, muscle weakness, sweating;
- Coronary pressure is greatly reduced;
- Attacks of nausea, vomiting;
- Fear, sudden panic attacks.
The part of the heart that has undergone necrosis does not perform its functions, and the remaining half continues to function as before. This may cause the dead section to rupture. If a person is not provided with urgent medical assistance, then the risk of death is high.
Heart rhythm disturbance
It is provoked by a spasmodic artery or untimely impulses that arise against the background of impaired conductivity of the coronary vessels.
Main symptoms:
- Feeling of tremors in the heart area;
- Abrupt fading of contractions of the heart muscle;
- Dizziness, blurriness, darkness in the eyes;
- Heaviness of breathing;
- Unusual manifestation of passivity (in children);
- Lethargy in the body, constant fatigue;
- Pressing and prolonged (sometimes acute) pain in the heart.
Rhythm disturbances often occur due to a slowdown in metabolic processes, if endocrine system not okay. Also, its catalyst can be long-term use of many medications.
This concept is a definition of insufficient activity of the heart, which causes a lack of blood supply to the entire body.
Pathology can develop as chronic complication arrhythmias, heart attack, weakening of the heart muscle.
Acute manifestations are most often associated with the intake of toxic substances, injuries and a sharp deterioration in the course of other heart diseases.
This condition requires urgent treatment, otherwise there is a high risk of death.
The development of heart failure is often diagnosed against the background of coronary vascular diseases. Main symptoms:
- Heart rhythm disturbances;
- Difficulty breathing;
- Coughing attacks;
- Clouding and darkening of the eyes;
- Swelling of the veins in the neck;
- Swelling of the legs, accompanied by painful sensations;
- Blackout;
- Severe fatigue.
Often this condition is accompanied by ascites (accumulation of water in the abdominal cavity) and liver enlargement. If the patient has persistent hypertension or diabetes mellitus, then it is impossible to make a diagnosis.
Coronary insufficiency
Heart coronary insufficiency– the most common type of ischemic disease. It is diagnosed if the circulatory system has partially or completely stopped supplying blood to the coronary arteries.
Main symptoms:
- Strong painful sensations in the region of the heart;
- Feeling of “not enough space” in the chest;
- Discoloration of urine and increased excretion;
- Pallor of the skin, change in its shade;
- The severity of the lungs;
- Sialorrhea (intense salivation);
- Nausea, vomiting, rejection of usual food.
In its acute form, the disease manifests itself as an attack of sudden cardiac hypoxia, which occurs due to spasm of the arteries. A chronic course is possible due to angina pectoris against the background of accumulation of atherosclerotic plaques.
There are three stages of the disease:
- Initial (mild);
- Expressed;
- A severe stage, which without proper treatment can lead to death.
Causes of vascular problems
There are several factors contributing to the development of IHD. Many of them are a manifestation of insufficient care for one’s health.
Important! Today, according to medical statistics, cardiovascular diseases are the No. 1 cause of death in the world.
Every year, more than two million people die from ischemic heart disease, most of whom are part of the population of “prosperous” countries with a comfortable sedentary lifestyle. The main causes of ischemic disease can be considered:
- Tobacco smoking, incl. passive smoke inhalation;
- Eating foods rich in cholesterol;
- Having excess weight (obesity);
- Physical inactivity, as a consequence of a systematic lack of movement;
- Exceeding the normal blood sugar level;
- Frequent nervous tension;
- Arterial hypertension.
There are also factors independent of a person that influence the condition of blood vessels: age, heredity and gender.
Women endure such illnesses more steadfastly and therefore they are characterized by a long course of the disease. And men more often suffer from acute forms of pathologies that end in death.
Methods of treatment and prevention of the disease
Correction of the condition or complete cure (in rare cases) is possible only after a detailed study of the causes of the disease.
To do this, carry out the necessary laboratory and instrumental studies. After this, a treatment plan is drawn up, the basis of which is medications.
Treatment involves the use of the following medications:
Surgical intervention is prescribed in case of ineffectiveness traditional therapy. To better nourish the myocardium, coronary bypass surgery is used - the coronary and external veins are connected where the intact portion of the vessels is located.
Coronary bypass surgery is a complex method that is performed on open heart, therefore it is used only in difficult situations, when it is impossible to do without replacing narrowed sections of the artery. Dilatation may be performed if the disease is associated with overproduction of the layer of the arterial wall. This intervention involves the introduction of a special balloon into the lumen of the vessel, expanding it in places where the membrane is thickened or damaged.
Heart before and after chamber dilatation Reducing the risk of complications
Own preventive measures reduce the risk of coronary artery disease. They also minimize Negative consequences V rehabilitation period after treatment or surgery.
The most simple tips, available to everyone:
- Refusal bad habits;
- Balanced diet ( Special attention for Mg and K);
- Daily walks in the fresh air;
- Physical activity;
- Control of blood sugar and cholesterol;
- Hardening and sound sleep.
The coronary system is a very complex mechanism that needs to be treated with care. Once manifested, the pathology steadily progresses, accumulating new symptoms and worsening the quality of life, so the recommendations of specialists and compliance with basic health standards should not be neglected.
Systematic strengthening of cardio-vascular system will keep your body and soul energetic for many years.
Video. Angina pectoris. Myocardial infarction. Heart failure. How to protect your heart.
Content
The human circulatory system is a complex mechanism consisting of a four-chamber muscular pump and many channels. The vessels that supply blood to organs are called arteries. These include the common carotid artery, which transports blood from the heart to the brain. Normal operation the body is impossible without effective blood circulation, since it carries essential microelements and oxygen.
What is the carotid artery
As already mentioned, this type artery is a vessel designed to supply food to the head and neck. The carotid vein has a wide shape necessary for the transfer large quantity oxygen, creating intense and continuous blood flow. Thanks to the artery, brain tissue is enriched, visual apparatus, face and other peripheral organs, due to which their work occurs.
Where is
People often have a question: how to find the carotid artery in the neck? To answer, you need to turn to basic anatomy human body. The common paired carotid artery originates in chest, then runs along the neck into the skull, ending at the base of the brain. The longer right branch arises from the brachiocephalic trunk, the left branch from the aorta. In the cervical region, the trunks lie along the anterior covering of the vertebral processes, and between them are the esophageal tube and trachea.
Structure
On the outside of the common SA there is the jugular vein, and among them in the groove is located nervus vagus: this is how it is formed neurovascular bundle. There are no branches along the vertical course of the bed, but at the thyroid cartilage, the carotid artery bifurcates into internal and external. The peculiarity of the vessel is the presence of an expansion (carotid sinus) with an adjacent nodule (carotid glomus). Outer sleepy channel consists of several groups of blood vessels:
- thyroid;
- linguistic;
- pharyngeal;
- facial;
- occipital;
- auricular posterior.
The location of the branch of the internal carotid artery is considered intracranial, since it enters the skull through a separate opening in the temporal bone. The area where the vessel connects to the basal artery through an anastomosis is called the circle of Willis. Segments of the internal carotid artery transport blood to visual organ, anterior and posterior regions of the brain, cervical vertebrae. This vein consists of seven vessels:
- connective;
- cavernous;
- cervical;
- ophthalmic;
- wedge-shaped;
- rocky;
- sector of the torn hole.
How many carotid arteries does a person have?
There is a misconception that a person has one carotid artery: in fact, there are two. They are located on both sides of the neck and are the most important sources blood circulation Next to these vessels there are two additional vertebral arteries, which are significantly inferior to the carotid arteries in terms of the volume of fluid transported. To feel the pulse, you need to find a point in the depression under the cheekbone on one side of the Adam's apple.
Functions
In addition to moving blood flow, the carotid arteries solve other, no less significant tasks. The carotid sinus is equipped with nerve cells whose receptors perform the following functions:
- monitor internal vascular pressure;
- react to change chemical composition blood;
- send signals about the presence of oxygen supplied by red blood cells;
- participate in regulating the activity of the heart muscle;
- control pulse;
- support arterial pressure.
What happens if you press on the carotid artery
Determining from your own experience the consequences of pressing on the carotid artery is strictly prohibited. If you press on this vessel for a short time, loss of consciousness occurs. This state lasts about five minutes, and when blood circulation resumes, the person awakens. Experiments with longer periods of force exposure can provoke severe degenerative processes, because the lack of oxygen is detrimental to brain cells.
Diseases
The external carotid filament does not directly supply blood to the brain. The non-stop opening of anastomoses, even with insufficiency of the circle of Willis, is explained by the good blood supply to this branch. Pathologies are characteristic mainly of the internal canal, although otolaryngologists, plastic and neurosurgeons in practice encounter problems with the functioning of the external canal. These include:
- congenital facial and cervical hemangiomas;
- malformation;
- arteriovenous fistula.
Chronic diseases, such as atherosclerosis, syphilis, muscular fibrous dysplasia, cause serious changes in the internal trunk. Possible reasons diseases of the carotid circulatory system are:
- inflammation;
- presence of plaque;
- artery blockage;
- formation of cracks in the canal wall (dissection);
- proliferation or delamination of the vessel lining.
The result of negative processes is a narrowing of the carotid artery. The brain begins to receive less nutrients and oxygen, then the clinical development of cell hypoxia occurs, ischemic stroke, thrombosis. Against this background, the following diseases of SA are distinguished:
- pathological arterial branching;
- trifurcation, which means division into three shoots;
- aneurysm;
- thrombus in the carotid artery.
Atherosclerosis
The normal appearance of the arterial wall is smooth and elastic. The formation of plaques helps to reduce the lumen of the trunk. The increase in deposits leads to a pronounced narrowing of the vessel. Carrying out diagnostics, doctors diagnose the patient with atherosclerosis of the carotid arteries. This condition refers to a number of serious diseases that provoke stroke and atrophy of brain tissue, and therefore requires immediate treatment. The presence of plaques in the carotid filament can be determined by the following symptoms:
- a sharp increase in cholesterol levels;
- frequent headaches;
- fainting;
- vision problems;
- rapid pulse;
- severe noise in the ears;
- numbness of the limbs;
- convulsions, confusion;
- speech disorder.
Carotid artery syndrome
A disease characterized by spasm of the vascular walls is recognized by medicine as carotid artery syndrome. Its occurrence is associated with the accumulation of a cholesterol layer along the edges of the channel, division of the membrane into several layers, and stenosis. Less commonly, the origin of the disease is caused by genetic predisposition, hereditary factors, and injuries.
Delamination inner surface arteries becomes the root cause of ischemic stroke in different age groups of people. Patients over fifty years of age are at risk, but recent research by scientists shows that the percentage of strokes in young people is growing. Prevention of the development of SA syndrome involves giving up bad habits and maintaining an active lifestyle.
Aneurysm
An expansion of the arterial zone with local thinning of the covering is called an aneurysm. The condition is preceded by inflammatory reactions, muscle atrophy, sometimes the disease is congenital. It is formed in the intracranial zones of the internal carotid branch and looks like a bag. The worst consequence such a formation is a rupture, leading to death.
Aneurysm should not be confused with carotid chemodectoma, which is related to benign tumors. According to statistics, 5% of cases result in cancer. The developmental path originates in the bifurcation area, continuing its movement under the jaw. During its life, the nuisance does not manifest itself in any way, so it is diagnosed by pathologists.
Treatment of diseases
Suggest pathology of the artery by clinical symptoms it is possible, but diagnosis is made only by doctors after appropriate examination. To study the organ, methods using modern technologies are used:
- Doppler observation;
- angiography;
- computed tomography.
The treatment regimen for the disease depends on the stage, size, and general condition. For example, in the initial course of thrombosis or a small aneurysm, anticoagulants and thrombolytics are prescribed. The expansion of the artery canal is carried out using novocaine isolation or removal of adjacent sympathetic accumulations. Severe narrowing, blockage and thrombosis of the carotid artery requires surgical intervention. Surgery on the carotid vessel is performed by stenting or removing the damaged area and replacing it with an artificial part.
Both elastic fibers and the outer one, consisting of fibrous connective tissue containing collagen fibers. The inner lining is formed by endothelium, which lines the lumen of the vessel, a subendothelial layer and an internal elastic membrane. The middle layer of the artery consists of spirally arranged smooth myocytes, between which a small amount of collagen and elastic fibers pass, and an outer elastic membrane formed by longitudinal thick intertwining fibers. The outer shell is formed by loose fibrous connective tissue containing elastic and collagen fibers; blood vessels and nerves pass through it (Fig. 204).
Depending on the development of the various layers of the artery wall, they are divided into vessels of the muscular (predominant), mixed (muscular-elastic) and elastic types. In the wall of muscular arteries, the tunica media is well developed. Myocytes and elastic fibers are located in it like a spring. Myocytes of the middle "shell of the wall of muscular arteries regulate blood flow to organs and tissues by their contractions. As the diameter of the arteries decreases, all the membranes of the artery walls become thinner. The thinnest arteries of the muscular type, arterioles with a diameter of less than 100 microns, pass into capillaries. To the arteries mixed type These include arteries such as the carotid and subclavian. In the middle shell of their wall there is approximately an equal number of elastic fibers and myocytes, fenestrated elastic membranes appear. Elastic arteries include the aorta and pulmonary trunk, into which blood flows under high pressure and at high speed from the heart.
The tunica media is formed by concentric elastic fenestrated membranes, between which myocytes lie.
The large arteries located near the heart (aorta, subclavian arteries and carotid arteries) have to withstand high pressure from the blood pushed out by the left ventricle of the heart. These vessels have thick walls, middle layer which consists mainly of elastic fibers. Therefore, during systole they can stretch without rupturing. After the end of systole, the arterial walls contract, which ensures continuous blood flow throughout the arteries.
Arteries located further from the heart have a similar structure, but contain more smooth muscle fibers in the middle layer. They are innervated by fibers of the sympathetic nervous system, and impulses arriving through these fibers regulate their diameter.
From the arteries, blood flows to more small vessels, called
The most important task of the cardiovascular system is to provide tissues and organs with nutrients and oxygen, as well as remove products of cell metabolism ( carbon dioxide, urea, creatinine, bilirubin, uric acid, ammonia, etc.). Enrichment with oxygen and removal of carbon dioxide occurs in the capillaries of the pulmonary circulation, and saturation with nutrients in the vessels of the systemic circulation as blood passes through the capillaries of the intestines, liver, adipose tissue and skeletal muscles.
a brief description of
The human circulatory system consists of the heart and blood vessels. Their main function is to ensure blood movement, carried out by working on the principle of a pump. When the ventricles of the heart contract (during their systole), blood is expelled from the left ventricle into the aorta, and from the right into the pulmonary trunk, from which the systemic and pulmonary circulations begin, respectively. The large circle ends with the inferior and superior vena cava, along which deoxygenated blood returns to the right atrium. And the small circle contains four pulmonary veins, through which arterial, oxygenated blood flows to the left atrium.
Based on the description, arterial blood flows through the pulmonary veins, which does not correlate with everyday ideas about circulatory system human (it is believed that venous blood flows through the veins, and arterial blood flows through the arteries).
Having passed through the cavity of the left atrium and ventricle, blood with nutrients and oxygen through the arteries enters the capillaries of the BCC, where oxygen and carbon dioxide are exchanged between it and the cells, nutrients are delivered and metabolic products are removed. The latter, through the bloodstream, reach the excretory organs (kidneys, lungs, gastrointestinal glands, skin) and are excreted from the body.
BKK and MKK are connected to each other in series. The movement of blood in them can be demonstrated using the following diagram: right ventricle → pulmonary trunk → pulmonary vessels → pulmonary veins → left atrium → left ventricle → aorta → systemic vessels → inferior and superior vena cava → right atrium → right ventricle.
Functional classification of vessels
Depending on the function performed and the structural features of the vascular wall, vessels are divided into the following:
- 1. Shock-absorbing (vessels of the compression chamber) - aorta, pulmonary trunk and large arteries of the elastic type. They smooth out periodic systolic waves of blood flow: they soften the hydrodynamic shock of the blood ejected by the heart during systole, and ensure the movement of blood to the periphery during diastole of the ventricles of the heart.
- 2. Resistive (resistance vessels) - small arteries, arterioles, metarterioles. Their walls contain great amount smooth muscle cells, thanks to the contraction and relaxation of which they can quickly change the size of their lumen. By providing variable resistance to blood flow, resistive vessels maintain blood pressure (BP), regulate the amount of organ blood flow and hydrostatic pressure in the vessels of the microvasculature (MCR).
- 3. Exchange - MCR vessels. Through the wall of these vessels there is an exchange of organic and inorganic substances, water, gases between blood and tissues. Blood flow in the vessels of the MCR is regulated by arterioles, venules and pericytes - smooth muscle cells located outside the precapillaries.
- 4. Capacitive - veins. These vessels have high distensibility, due to which they can deposit up to 60–75% of the circulating blood volume (CBV), regulating the return of venous blood to the heart. The veins of the liver, skin, lungs and spleen have the greatest depositing properties.
- 5. Bypass - arteriovenous anastomoses. When they open, arterial blood is discharged along a pressure gradient into the veins, bypassing the MCR vessels. For example, this happens when the skin is cooled, when the blood flow is directed through arteriovenous anastomoses, bypassing the skin capillaries, to reduce heat loss. The skin turns pale.
Pulmonary (lesser) circulation
The ICC serves to saturate the blood with oxygen and remove carbon dioxide from the lungs. After blood enters the pulmonary trunk from the right ventricle, it is sent to the left and right pulmonary arteries. The latter are a continuation of the pulmonary trunk. Each pulmonary artery, after passing through the hilum of the lung, branches into smaller arteries. The latter, in turn, pass into the MCR (arterioles, precapillaries and capillaries). In the MCR, venous blood is converted into arterial blood. The latter enters from the capillaries into venules and veins, which, merging into 4 pulmonary veins (2 from each lung), flow into the left atrium.
Bodily (large) circle of blood circulation
BKK serves to deliver nutrients and oxygen to all organs and tissues and remove carbon dioxide and metabolic products. After blood enters the aorta from the left ventricle, it is directed into the aortic arch. Three branches depart from the latter (brachiocephalic trunk, common carotid and left subclavian artery), which supply blood upper limbs, head and neck.
After this, the aortic arch passes into the descending aorta (thoracic and abdominal). The latter at the level of the fourth lumbar vertebra is divided into common iliac arteries, which supply blood lower limbs and pelvic organs. These vessels are divided into external and internal iliac arteries. The external iliac artery passes into the femoral artery, supplying arterial blood to the lower extremities below the inguinal ligament.
All arteries, heading to tissues and organs, in their thickness pass into arterioles and then into capillaries. In the MCR, arterial blood is converted into venous blood. Capillaries become venules and then veins. All veins accompany arteries and are named similarly to arteries, but there are exceptions (portal vein and jugular veins). Approaching the heart, the veins merge into two vessels - the inferior and superior vena cava, which flow into the right atrium.
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