The veins of the great circle of blood circulation. The process of blood circulation. Anatomy
Venous vessels are the most important part of the body's "heart-vessels" system, closely interrelated with lymph and arteries. Thanks to the venous system, the flow of lymph and blood to the heart is ensured.
The veins of the great circle of blood circulation are a closed system of vessels that collect oxygen-depleted blood from all cells of the body and tissues, united by the following subsystems:
- cardiac veins;
- upper hollow vein;
- inferior vena cava.
The difference between venous and arterial blood
Venous blood is the blood that flows back from all cellular systems and tissues, saturated with carbon dioxide containing metabolic products.
Medical manipulation and research is conducted mainly with such blood, which contains the final products of metabolism and a smaller amount of glucose.
Arterial blood is blood that flows to all cells and tissues from the heart muscle, saturated with oxygen and hemoglobin, containing nutrients.
Oxygenated arterial blood circulates th
The structure of veins
The walls of venous vessels are much thinner than arterial vessels, since the blood flow velocity in them and the pressure are lower. The veins are stretched lighter, their elasticity is lower than the arteries. Vascular valves are usually located opposite, which prevents reverse flow of blood. A large number of valves are located in the lower extremities of the veins. In the veins are also semilunar valves from the folds of the inner shell, which have a special elasticity. In the hands and feet there are venous vessels located between the muscles, this at a muscle contraction allows the blood to return back to the heart.
A large circle originates in the left ventricle of the heart, and from it comes the aorta with a diameter of up to three centimeters. Then, the oxygenated blood of the arteries comes through the vessels decreasing in diameter to all organs. After giving all the useful substances, the blood is saturated with carbon dioxide and goes back already through the venous system through the smallest vessels - venules, while the diameter gradually increases, approaching the heart. Venous blood from the right atrium is pushed out to the right ventricle, and a small circle of blood begins. Entering the lungs, the blood is again filled with oxygen. Arterial blood flows through the veins into the left atrium, which is then pushed out into the left ventricle of the heart, and the circle repeats itself.
Arteries and veins of the great circulation range include the aorta, as well as the smaller, upper and lower hollow vessels branching off from it.
Small capillaries make up about 1,500 square meters in the human body.
The veins of the great circle of blood carry depleted blood, in addition to the umbilical and pulmonary, which carry the arterial, oxygenated blood.
Cardiac vein system
- veins of the heart that go directly into the heart cavity;
- coronary sinus;
- is a large cardiac vein;
- left ventricular posterior vein;
- left atrial slanting vein;
- anterior vessels of the heart;
- medium and small veins;
- atrial and ventricular;
- is the smallest venous blood vessel of the heart;
The driving force of the blood flow is the energy given by the heart, as well as the pressure difference in the vascular sections.
The upper hollow vein system
The upper hollow vein takes the venous blood of the upper body - the head, neck, sternum and partly the abdominal cavity and gets into the right atrium. The valves of the vessels are absent. The process is as follows: the blood of the upper vein, saturated with carbon dioxide, flows into the pericardium, and below the right atrium. The system of the superior vena cava is divided into such parts:
- Upper hollow - a small vessel, 5-8 cm in length, 2.5 cm in diameter.
- Unpaired - continuation of the right ascending lumbar vein.
- Semi-continuous - continuation of the left anisy lumbar vein.
- Posterior intercostal - collection of veins of the back, its muscles, external and internal vertebral plexuses.
- Intravertebral venous connections - located inside the vertebral canal.
- Brachiocephalic - the roots of the upper cavity.
- Vertebral - location in diametrical orifices of cervical vertebrae.
- Deep neck is the collection of venous blood from the occipital region along the carotid artery.
- Internal thoracic.
The lower hollow vein system
The lower hollow is the connection of the iliac veins from two sides in the region of 4 to 5 vertebrae of the waist, taking the venous blood from the lower parts of the body. The lower hollow is one of the largest veins in the body. The length is about 20 cm, in diameter up to 3.5 cm. Thus, from the lower hollow there is an outflow of blood from the legs, pelvis and abdomen. The system is divided into the following components:
- Lower hollow vein.
- Lumbar veins - abdominal cavity.
- Lower diaphragmatic - collection of blood from the lower area of the diaphragm.
- Group of internal vessels - includes renal and adrenal, vessels of testicles and ovaries, hepatic veins.
- Gateway - unites blood from unpaired organs of the peritoneum - stomach, liver, spleen and pancreas, as well as partially the intestine.
- Lower mesenteric - includes the upper part of the rectum, sigmoid and descending colon.
- Upper mesenteric - includes the small intestine, the cecum and the appendix.
The portal vein has its name due to the ingress of the trunk into the gates of the liver, as well as the collection of venous blood from the digestive organs - the stomach, spleen, intestine thick and thin. Its vessels are located behind the pancreas. The length of the vessel is 500-600 mm, in diameter - 110-180 mm.
Inflows of the visceral trunk are the superior mesenteric, inferior mesenteric and splenic vessels.
The portal vein anatomy system basically consists of stomach vessels, intestines of thick and thin sections, pancreas, gall bladder and spleen. In the liver, it divides into the right and left and then branches into smaller veins. As a result, they are connected to the central veins of the liver, poddolkovye veins of the liver. And in the end, three or four hepatic vessels are formed. Thanks to this system, the blood of the digestive organs passes through the liver, entering the subsystem of the inferior vena cava.
The superior mesenteric vein accumulates blood in the roots of the mesentery of the small intestine from the ileum, pancreatic, right and middle colon, ileal and right ventricle-glandular veins.
The inferior mesenteric vein is formed from the upper rectal, sigmoid and left colonic veins.
Splenic vein combines splenic blood, blood of the stomach, duodenum and pancreas.
Jugular veins system
From the base of the skull to the supraclavicular cavity, the jugular vein vessel passes. A large circle of blood circulation includes these veins, which are key collectors of blood from the head and neck. In addition to the internal, the blood from the head and soft tissues collects and external jugular vein. The external begins in the area of the auricle and goes down, along the sternocleidomastoid muscle.
Veins coming from the external jugular:
- posterior ear - collection of venous blood behind the auricle;
- occipital branch - collection from the venous plexus of the head;
- suprascapular - receiving blood from the formations of the periostal cavity;
- transverse veins of the neck - satellites of the transverse cervical arteries;
- anterior jugular - consists of chinens, veins of the maxillofacial and sternum-thyroid muscles.
The internal jugular vein begins in the jugular cavity of the skull, being a companion of the external and internal carotid arteries.
Functions of the large circle
It is thanks to the continuous movement of blood in the arteries and veins of the great circle of circulation that the basic functions of the system are provided:
- transport of substances to ensure the functions of cells and tissues;
- transport of essential chemicals for metabolic reactions in cells;
- collection of metabolites of cells and tissues;
- the connection of tissues and organs to each other by means of blood;
- transport to protective cell cells;
- sampling of harmful substances from the body;
- heat exchange.
The vessels of this circle of blood circulation represent a branched network that provides blood to all organs in contrast to the small circle. Optimum functioning of the system of the upper and lower hollow veins leads to competent blood supply of all organs and tissues.