The human heart is a 4-chamber muscular hollow organ that receives venous blood from all organs and tissues and drives fresh, oxygenated blood into the arteries. The chambers of the heart are 2 atria and 2 ventricles. For brevity, they are called, for example, in deciphering the ECG, LV and RV, and the atria - respectively LA and PP.
General information
The left 2 chambers together make up the left or arterial heart - according to the property of the blood in them; accordingly, the right half is the venous or right heart. Contraction of the heart muscle - systole, relaxation - diastole. The atria are the receiving chambers, the ventricles eject blood into the arteries.
There are partitions between all chambers. Thanks to them, the blood of the veins and arteries in the heart does not mix. In each half of the heart, the chambers communicate with each other due to the presence of heart valves (atrioventricular openings). Through these openings, blood during atrial systole is directed from them into the cavities of the ventricles. The arteries and veins of the heart have their own peculiarities of structure and work.
Venous circulation systemoverall
A vein is a vessel that promotes blood from organs to the heart, this blood is saturated after washing the organs with carbon dioxide, unlike the arterial one, which is saturated with oxygen.
Blood in the veins is collected from the capillaries, which are getting larger and larger, moving in increasing caliber into venules, then into veins, and finally form the vena cava.
The venous network is an integral part of the cardiovascular system, and phlebology deals with it. The largest veins in the network are the vena cava (superior and inferior).
In the superior vena cava of the heart are the blood streams of the upper body - the shoulder girdle, head, neck (the lungs are not included here). And in the lower on the other side - the legs and abdominal organs. All this forms a large circle of blood circulation. The vena cava of the heart is the largest vein in the great circle, in which the heart itself serves as the main pump.
The portal vein flows into the RA and from there into the RV. Further, blood from the heart from the vein enters the pulmonary artery and is sent to the lungs to be saturated with oxygen.
On average, blood passes through the entire venous network of the great circle in 23-27 seconds, although its speed is slower compared to the arteries.
The veins experience a lot of stress because the blood here is pushed through the veins, overcoming gravity. Venous blood, entering the right atrium, goes to the right ventricle and from there to the pulmonary artery and lungs. Here it is cleared, it is oxygenated, and it turns into arterial.
Fresh pure blood enters 4 pulmonary veinssequentially into the left atrium, LV and into the aorta. From there, it spreads throughout the body. The cycle is repeated anew. The path of blood flow from the pancreas to the pulmonalis artery, then to the lungs and again to the left ventricle, is called the pulmonary circulation or pulmonary.
Venous circulation of the heart
The main difference between the veins of the heart is that they open directly inside the heart, into its cavity. They are located both on the surface of the heart muscle and inside the myocardium (intramuscular veins), along the muscle bundles. There are more of them in the right heart than in the left half.
There are 7 main veins of the heart:
- coronary sinus;
- anterior veins;
- posterior, middle, oblique and large vein;
- small veins.
The coronary sinus is the largest, it opens directly into the RA. Its caliber is 10-12 mm, its length is from 1.5 to 5.8 cm. Topographically, it is located below the portal inferior vein in the coronal sulcus on the left (the coronal sulcus separates the atria and ventricles). 3 veins flow into it: the middle vein of the heart, the oblique vein of the LA and the posterior vein of the LV.
The middle is located in the posterior interventricular sulcus and begins on the posterior surface of the heart near its apex. It flows from the right side into the coronary sinus after it collects blood from the posterior wall of both ventricles.
The oblique vein of the LA begins on its posterior wall, goes down diagonally to the right and also enters the coronary sinus.
Posterior - LV - starts from it, at the apex of the LV heart and ends in the coronary sinus. Thus, it turns out that the coronary sinus is the largest collector in the network of coronary vessels. It collects waste blood from the ventricles and part of the atria. It is generally accepted that the coronary sinus is a continuation of a large vein.
The large vein is a collector of small veins of the anterior walls of both ventricles, the interventricular septum and the vein of the left edge of the heart.
Next, it emerges from the apex of the heart muscle on its anterior surface, passes in the interventricular groove, passes into the coronary sulcus and goes around the left edge of the heart, passing into the coronary sinus.
The anterior veins are located on the anterior surface of the pancreas and flow into the RA. They collect blood from the anterior wall of the pancreas.
Also, small veins flow into the PP after collecting blood from the walls of the heart. The venous volume of blood flow significantly exceeds the arterial one.
Veins, as you can see, there are a lot of veins in such a relatively small organ, but they are all the smallest in the body. They can only collect blood from its wall areas.
Venous meshes
The veins of the heart look like grids that are located in different layers of the heart muscle. These networks are created by dense plexuses of venules. Anastomosing myocardial veins run clearly along the muscle bundles.
In general, networks of plexuses are localized under the endocardium and inside it, inside the myocardium, inside the epicardium, and the most powerful - under the epicardium. The veins of the heart are usually not associated with the location of the arteries, they are single.
In the interventricular septum there are separately 2 more powerful venous bundles. They are formed in the anterior andposterior upper sections of the specified septum on its border with the atria. These are the most important venous collectors of the heart, collecting blood from the legs of the bundle of His and from the septum of the ventricles. These are the main components of the conductive system.
Venous outflow of the heart
Established 2 types of venous outflow. The first type - they talk about it when the development of the magna vein (large vein) predominates - 44.2%. It drains blood from the ventricles. The second type of outflow is with the advantage of the system of the anterior veins of the heart (42.5%), through which blood is drained not only from the entire pancreas, but also from part of the left ventricle of the heart. But in any case, as you can see, the blood supply to the heart does not suffer. There are many anastomoses between the leading vessels.
Arteries of the heart
The heart receives arterial blood, as a rule, from two coronary (coronary) arteries - left and right. The latter originate from the aortic bulb, in their appearance they look like a crown, which is why their other name came from - coronary. They supply blood to all the walls of the heart. For example, the left coronary artery supplies the LA, LV, part of the anterior wall of the RV, 70% of the interventricular septum, and the anterior papillary muscle of the LV.
What are the papillary muscles and are they really that important? Papillary muscles have another name - papillary. They are outgrowths in the endocardium and protrude directly into the cavity of the ventricles. Together with the chords of the apex, they help the unidirectional movement of blood. The arteries also anastomose with each other. The right artery is obliquely directedto the right, to the auricle of the right atrium. It supplies the wall sections of the pancreas and right ventricle, the papillary muscles of the left ventricle, the sinus node (pacemaker), part of the interventricular septum.
Atrial nodes are the conduction system of the heart. Its largest branch, the posterior interventricular branch, is located in the sulcus of the same name and descends to the myocardial apex.
The left coronary artery is thicker and runs between the LA auricle and the pulmonary trunk. It divides into the anterior interventricular and oblique branches. The circumflex actually continues the main trunk and goes around the heart on the left along the coronary sulcus. Further on its posterior surface, it joins with the right coronary artery. In the layers of the myocardium, the vessels follow the course of the muscle fibers.
Intraorgan arteries of the heart
These are the branches of the main coronary arteries and their large branches, are called ramuses. They are directed directly to 4 chambers of the heart: branches of the atria and their ears, branches of the ventricles, septal branches - anterior and posterior. Having penetrated into the thickness of the myocardium, they actively branch further, according to the number of its layers, thus resembling the structure of venous networks: first in the outer layer, then in the middle (in the ventricles) and, finally, in the inner - endocardial, after which they penetrate into the papillary muscles (aa. papillares) and even into heart valves. Their course also corresponds to the muscle bundles.
They all anastomose with each other. Anastomoses and collaterals are very important because it is thanks to them that blood flow is restored in ischemic areas, i.e. with myocardial infarction.
