Dark blood from a vein. Which vessels does darker blood move through and how does the circulatory system work?

Constant movement of blood through a closed circuit cardiovascular system, which ensures gas exchange in tissues and lungs, is called blood circulation. In addition to saturating organs with oxygen, as well as cleansing them of carbon dioxide, blood circulation is responsible for delivering all necessary substances to the cells.

Everyone knows that blood can be venous and arterial. In this article you will learn through which vessels more dark blood, find out what is included in this biological fluid.

This system includes blood vessels, which penetrate all tissues of the body and the heart. The process of blood circulation begins in the tissues where metabolic processes through the capillary walls.

The blood, which has given up all its useful substances, flows first to right half heart, and then into the pulmonary circulation. There she became rich useful substances, moves to the left, and then spreads in a large circle.

The heart is the main organ in this system. It is endowed with four chambers - two atria and two ventricles. The atria are divided interatrial septum, and the ventricles - interventricular. The weight of a human “motor” is from 250-330 grams.

The color of the blood in the veins and the color of the blood moving through the arteries are slightly different. You will learn a little later about which vessels the darker blood moves through and why it differs in shade.

An artery is a vessel that carries biological fluid saturated with useful substances from the “motor” to the organs. The answer to a fairly frequently asked question: “What vessels carry venous blood?” simple Venous blood is transported exclusively by the pulmonary artery.

The arterial wall consists of several layers, these include:

outer connective tissue membrane;
medium (consisting of smooth muscles and elastic hairs);
internal (consisting of connective tissue and endothelium).

Arteries divide into small vessels called arterioles. As for capillaries, they are the smallest vessels.

The vessel that carries carbon dioxide-rich blood from tissues to the heart is called a vein. The exception in this case is the pulmonary vein, since it carries arterial blood.

Dr. W. Harvey first wrote about blood circulation back in 1628. The circulation of biological fluid occurs through the pulmonary and systemic circulation.

The movement of biological fluid in the systemic circle begins from the left ventricle, thanks to high blood pressure, the blood spreads throughout the body, nourishes all organs with beneficial substances and takes away harmful ones. Next, the transformation of arterial blood into venous blood is noted. Final stage- return of blood to the right atrium.

As for the small circle, it begins from the right ventricle. First, the blood gives off carbon dioxide, receives oxygen, and then moves to the left atrium. Next, through the right ventricle, the flow of biological fluid into the systemic circle is noted.

The question of which vessels carry darker blood is quite common. Blood is red in color; it differs only in shades due to the amount of hemoglobin and oxygen enrichment.

Surely many remember from biology lessons that arterial blood has a scarlet tint, and venous has a dark red or burgundy tint. Veins located nearby skin, also appear red when blood circulates through them.

In addition, venous blood differs not only in color, but also in function. Now, knowing through which vessels darker blood moves, you know that its color is due to its enrichment in carbon dioxide. The blood in the veins has a burgundy tint.

It contains little oxygen, but at the same time it is rich in metabolic products. It is more viscous. This is due to an increase in the diameter of red blood cells due to the influx of carbon dioxide into them. Moreover, the temperature venous blood higher, and the pH is lower.

It circulates through the veins very slowly (due to the presence of valves in the veins that slow down the speed of its movement). Wen in human body compared to arteries, much larger.

What color is the blood in the veins and what functions does it perform?

Do you know what color the blood in the veins is? The shade of biological fluid determines the presence of hemoglobin in red blood cells (erythrocytes). The blood circulating through the arteries, as already mentioned, is scarlet.

This is due to the high concentration of hemoglobin (in humans) and hemocyanin (in arthropods and mollusks), enriched with various nutrients.

Venous blood has a dark red tint. This is due to oxidized and reduced hemoglobin.

At the very least, it is unreasonable to believe the theory according to which the biological fluid circulating through the vessels is bluish in color, and when injured and in contact with air due to chemical reaction immediately blushes. It is a myth.

Veins may only appear bluish, this is due to simple laws physicists. When light hits the body, the skin reflects some of all the waves and therefore looks light or dark (this depends on the concentration of the coloring pigment).

You know what color venous blood is, now let's talk about the composition. You can distinguish arterial blood from venous blood using laboratory research. Oxygen tension - 38-40 mmHg. (in venous), and in arterial blood - 90. The content of carbon dioxide in venous blood is 60 millimeters of mercury, and in arterial blood - about 30. The pH level in venous blood is 7.35, and in arterial blood - 7.4.

The outflow of blood, carrying away carbon dioxide and products formed during metabolism, is carried out through the veins. It is enriched with useful substances that are absorbed into the walls of the gastrointestinal tract and produced by vital substances.

Now you know what color the blood is in the veins, you are familiar with its composition and functions.

Blood flowing through the veins overcomes “difficulties” during movement, which include pressure and gravity. That is why, in case of damage, biological fluid flows in a slow stream. But if the arteries are injured, blood spurts out like a fountain.

The speed at which venous blood moves is much less than the speed at which arterial blood moves. The heart pumps blood out under high pressure. After it passes through the capillaries and becomes venous, a decrease in pressure to ten millimeters of mercury is noted.

Why is venous blood darker than arterial blood, and how to determine the type of bleeding

You already know why venous blood is darker than arterial blood. Arterial blood is lighter and this is due to the presence of oxyhemoglobin in it. As for the venous, it is dark (due to the content of both oxidized and reduced hemoglobin).

You've probably noticed that blood is taken from a vein for testing, and you've probably wondered, “why from a vein?” This is due to the following. The composition of venous blood includes substances that are formed during metabolism. In pathologies, it is enriched with substances that ideally should not be in the body. Thanks to their presence, it is possible to identify the pathological process.

Now you know not only why the blood in the veins is darker than the arterial blood, but also why blood is taken from the vein.

Anyone can determine the type of bleeding; there is nothing difficult about it. The main thing is to know the characteristics of biological fluid. Venous blood has a darker shade (why venous blood is darker than arterial blood is indicated above), and it is also much thicker. When cut, it flows out in a slow stream or drops. But as for the arterial one, it is liquid and bright. When wounded, it sprays like a fountain.

It is easier to stop venous bleeding; sometimes it stops on its own. Typically, a tight bandage is used to stop bleeding (placed below the wound).

As for arterial bleeding, everything is much more complicated. It is dangerous because it does not stop on its own. In addition, blood loss can be so large that death can occur literally within an hour.

Capillary bleeding can open even with minimal injury. The blood flows out calmly, in a small stream. Such damage is treated with brilliant green. Next, a bandage is applied to them, which helps stop bleeding and prevent contact with pathogenic microorganisms into the wound.

As for the venous, when damaged, blood flows out somewhat faster. In order to stop bleeding, a tight bandage is applied, as already mentioned, below the wound, that is, further from the heart. Next, the wound is treated with 3% peroxide or vodka and bandaged.

As for the arterial one, it is the most dangerous. If an injury occurs and you see bleeding from an artery, you must immediately raise the limb as high as possible. Next, you need to bend it and pinch the wounded artery with your finger.

Then a rubber tourniquet (rope or bandage will do) is applied above the wound site, after which it is tightened tightly. The tourniquet must be removed no later than two hours after application. While the bandage is being applied, a note is attached indicating the time of application of the tourniquet.

Bleeding is dangerous and fraught great loss blood and even fatal. That is why in case of injury it is necessary to call ambulance or take the patient to the hospital yourself.

Now you know why the blood in the veins is darker than the blood in the arteries. Blood circulation is a closed system, which is why the blood in it is either arterial or venous.

Venous circulation occurs as a result of the rotation of blood to the heart, and in general, through the veins. It is deprived of oxygen, as it is completely dependent on carbon dioxide, which is necessary for tissue gas exchange.

As for human venous blood, as opposed to arterial blood, then it is several times warmer and has a lower pH. In its composition, doctors note low content majority nutrients, including glucose. It is characterized by the presence of metabolic end products.

In order to obtain venous blood, you must undergo a procedure called venipuncture! Basically everything medical research V laboratory conditions They take venous blood as a basis. Unlike the arterial one, it has a characteristic color with a red-bluish, deep tint.

About 300 years ago, an explorer Van Horn made a sensational discovery: It turns out that the entire human body is penetrated by capillaries! The doctor begins to conduct various experiments with medications, as a result of which he observes the behavior of capillaries filled with red liquid. Modern doctors know that capillaries play a key role in the human body. With their help, blood flow is gradually ensured. Thanks to them, all organs and tissues are supplied with oxygen.

Human arterial and venous blood, difference

From time to time, everyone wonders: is venous blood different from arterial blood? The entire human body is divided into numerous veins, arteries, large and small vessels. Arteries facilitate the so-called outflow of blood from the heart. Purified blood moves throughout the human body and thus provides timely nutrition.

In this system, the heart is a kind of pump that gradually pumps blood throughout the body. Arteries can be located both deep and close under the skin. You can feel the pulse not only on the wrist, but also on the neck! Arterial blood has a characteristic bright red hue, which when bleeding takes on a somewhat poisonous color.

Human venous blood, unlike arterial blood, is located very close to the surface of the skin. Along its entire surface, venous blood is accompanied by special valves that facilitate the calm and smooth passage of blood. Dark blue blood nourishes tissues and gradually moves into the veins.

In the human body there are several times more veins than arteries. If any damage occurs, venous blood flows slowly and stops very quickly. Venous blood is very different from arterial blood, and all because of the structure of individual veins and arteries.

The walls of veins are unusually thin, unlike arteries. They can withstand high pressure, since powerful tremors may be observed during the ejection of blood from the heart.

In addition, elasticity plays a key role, thanks to which blood moves through the vessels quickly. Veins and arteries provide normal blood circulation, which does not stop for a minute in the human body. Even if you are not a doctor, it is very important to know a minimum of information about venous and arterial blood that will help you in case open bleeding quickly provide first aid medical care. The World Wide Web will help replenish the stock of knowledge regarding venous and arterial circulation. You just need to enter the word of interest into the search bar and in a few minutes you will receive answers to all your questions.

In medicine, blood is usually divided into arterial and venous. It would be logical to think that the first flows in the arteries, and the second in the veins, but this is not entirely true. The fact is that in the systemic circulation, arterial blood (a.k.) actually flows through the arteries, and venous blood (v.k.) through the veins, but in the small circle the opposite happens: c. to. comes from the heart to the lungs through the pulmonary arteries, gives off carbon dioxide out, enriched with oxygen, becomes arterial and returns from the lungs through the pulmonary veins.

How does venous blood differ from arterial blood? A.K. is saturated with O 2 and nutrients; it flows from the heart to organs and tissues. V. k. - “spent”, it gives O 2 and nutrition to the cells, takes CO 2 and metabolic products from them and returns from the periphery back to the heart.

Human venous blood differs from arterial blood in color, composition and functions.

By color

A.K. has a bright red or scarlet tint. This color is given to it by hemoglobin, which added O 2 and became oxyhemoglobin. V.K. contains CO 2, so its color is dark red, with a bluish tint.

By composition

In addition to gases, oxygen and carbon dioxide, the blood also contains other elements. In a. k. a lot of nutrients, and c. to. - mainly metabolic products, which are then processed by the liver and kidneys and excreted from the body. The pH level also differs: in a. k. it is higher (7.4) than that of v. k. (7.35).

By movement

Blood circulation in arterial and venous systems significantly different. A. K. moves from the heart to the periphery, and c. k. - in the opposite direction. When the heart contracts, blood is ejected from it under a pressure of approximately 120 mmHg. pillar As it passes through the capillary system, its pressure decreases significantly and is approximately 10 mmHg. pillar Thus, a. k. moves under pressure from high speed, and c. It flows slowly under low pressure, overcoming the force of gravity, and its reverse flow is prevented by valves.

How the transformation of venous blood into arterial blood and vice versa occurs can be understood if we consider the movement in the pulmonary and systemic circulation.

Blood saturated with CO 2 enters the lungs through the pulmonary artery, from where CO 2 is excreted. Then saturation with O 2 occurs, and the blood already enriched with it enters the heart through the pulmonary veins. This is how movement occurs in the pulmonary circulation. After this, the blood makes a large circle: a. It carries oxygen and nutrition through the arteries to the cells of the body. Giving up O 2 and nutrients, it is saturated with carbon dioxide and metabolic products, becomes venous and returns through the veins to the heart. This completes the large circle of blood circulation.

By functions performed

Main function a. k. – transfer of nutrition and oxygen to cells through arteries great circle blood circulation and small veins. Passing through all organs, it gives off O 2, gradually takes up carbon dioxide and turns into venous.

The veins carry out the outflow of blood, which has taken away cell waste products and CO 2 . In addition, it contains nutrients that are absorbed digestive organs, and produced by glands internal secretion hormones.

By bleeding

Due to the characteristics of movement, bleeding will also differ. With arterial bleeding, the blood flows in full swing; such bleeding is dangerous and requires prompt first aid and medical attention. With venous flow, it calmly flows out in a stream and can stop on its own.

Other differences

A.K. is located on the left side of the heart, in. k. – in the right, blood mixing does not occur.
Venous blood, unlike arterial blood, is warmer.
V. k. flows closer to the surface of the skin.
A.K. in some places comes close to the surface and here the pulse can be measured.
The veins through which the v. flows. to., much more than arteries, and their walls are thinner.
Movement a.k. is ensured by a sharp release during contraction of the heart, outflow into the. the valve system helps.
The use of veins and arteries in medicine is also different - they inject medications, it is from this that biological fluid is taken for analysis.

Instead of a conclusion

Main differences a. k. and v. consist in the fact that the first is bright red, the second is burgundy, the first is saturated with oxygen, the second is saturated with carbon dioxide, the first moves from the heart to the organs, the second - from the organs to the heart.

Blood circulates in the human body in closed system. The main function of biological fluid is to provide cells with oxygen and nutrients and remove carbon dioxide and metabolic products.

A little about the circulatory system

The human circulatory system has complex device, biological fluid circulates in the pulmonary and systemic circulation.

The heart, which acts as a pump, consists of four sections - two ventricles and two atria (left and right). Vessels, blood bearers from the heart are called arteries, to the heart are called veins. The arterial one is enriched with oxygen, the venous one – with carbon dioxide.

Thanks to interventricular septum, venous blood, which is on the right side of the heart, does not mix with arterial blood, which is on the right side. Valves located between the ventricles and atria and between the ventricles and arteries prevent it from flowing in the opposite direction, that is, from the largest artery (aorta) to the ventricle, and from the ventricle to the atrium.

When the left ventricle, whose walls are thickest, contracts, it creates maximum pressure, oxygen-rich blood is pushed into the systemic circulation and distributed through the arteries throughout the body. In the capillary system, gases are exchanged: oxygen enters the tissue cells, carbon dioxide from the cells enters the bloodstream. Thus, the arterial becomes venous and flows through the veins to right atrium, then into the right ventricle. This is a large circle of blood circulation.

Next, the venous blood flows through the pulmonary arteries into the pulmonary capillaries, where it releases carbon dioxide into the air and is enriched with oxygen, again becoming arterial. Now it flows through the pulmonary veins into the left atrium, then into the left ventricle. This closes the pulmonary circulation.

Venous blood is found in the right side of the heart

Characteristics

Venous blood differs in a number of parameters, ranging from appearance and ending with the functions performed.

Many people know what color it is. Due to its saturation with carbon dioxide, its color is dark, with a bluish tint.
It is poor in oxygen and nutrients, but it contains a lot of metabolic products.
Its viscosity is higher than that of oxygen-rich blood. This is explained by an increase in the size of red blood cells due to the entry of carbon dioxide into them.
She has more high temperature and more low level pH.
Blood flows through the veins slowly. This is due to the presence of valves in them, which slow down its speed.
There are more veins in the human body than arteries, and venous blood overall accounts for approximately two-thirds of the total volume.
Due to the location of the veins, it flows close to the surface.

Compound

Laboratory tests make it easy to distinguish venous blood from arterial blood by composition.

In the venous oxygen tension is normally 38-42 mmHg (in the arterial - from 80 to 100).
Carbon dioxide - about 60 mm Hg. Art. (in arterial – about 35).
The pH level remains 7.35 (arterial - 7.4).

Functions

The veins carry out the outflow of blood, which carries metabolic products and carbon dioxide. Nutrients enter it and are absorbed by the walls. digestive tract, and hormones produced by the endocrine glands.

Movement through the veins

During its movement, venous blood overcomes gravity and experiences hydrostatic pressure, therefore, if a vein is damaged, it calmly flows in a stream, and if an artery is damaged, it flows in full swing.

Its speed is much lower than that of the arterial one. The heart pumps out arterial blood at a pressure of 120 mmHg, and after it passes through the capillaries and becomes venous, the pressure gradually drops and reaches 10 mmHg. pillar

Why is material taken from a vein for analysis?

Venous blood contains breakdown products formed during the metabolic process. During diseases, substances enter it, which are in in good condition there shouldn't be. Their presence allows one to suspect the development of pathological processes.

How to determine the type of bleeding

Visually, this is quite easy to do: the blood from the vein is dark, thicker and flows out in a stream, while the arterial blood is more liquid, has a bright scarlet hue and flows out like a fountain.

Venous bleeding is easier to stop; in some cases, if a blood clot forms, it may stop on its own. Usually required pressure bandage, applied below the wound. If a vein in the arm is damaged, it may be enough to raise the arm up.

As for arterial bleeding, it is very dangerous because it will not stop on its own, the blood loss is significant, and death can occur within an hour.

Conclusion

The circulatory system is closed, so the blood, as it moves, becomes either arterial or venous. Enriched with oxygen, when passing through the capillary system, it gives it to tissues, takes up decay products and carbon dioxide and thus becomes venous. After this, it rushes to the lungs, where it loses carbon dioxide and metabolic products and is enriched with oxygen and nutrients, again becoming arterial.

In order to notice any disturbances in the body in time, you need at least basic knowledge of the anatomy of the human body. It’s not worth delving deeply into this issue, but having an idea of the simplest processes is very important. Today let's find out how venous blood differs from arterial blood, how it moves and through which vessels.

The main function of blood is to transport nutrients to organs and tissues, in particular, the supply of oxygen from the lungs and the return movement of carbon dioxide to them. This process can be called gas exchange.

Blood circulation occurs in a closed system of blood vessels (arteries, veins and capillaries) and is divided into two circles of blood circulation: small and large. This feature allows it to be divided into venous and arterial. As a result, the load on the heart is significantly reduced.

Let's look at what kind of blood is called venous and how it differs from arterial. This type of blood primarily has a dark red color, sometimes they also say that it has a bluish tint. This feature is explained by the fact that it transports carbon dioxide and other metabolic products.

The acidity of venous blood, in contrast to arterial blood, is slightly lower, and it is also warmer. It flows through the vessels slowly and quite close to the surface of the skin. This occurs due to the structural features of the veins, which contain valves that help reduce the speed of blood flow. It also has extremely low levels of nutrients, including a reduction in sugar.

In the vast majority of cases, this type of blood is used for testing during any medical examinations.

Venous blood goes to the heart through the veins, has a dark red color, and carries metabolic products

At venous bleeding coping with the problem is much easier than with a similar process from the arteries.

Number of veins in human body several times the number of arteries, these vessels ensure blood flow from the periphery to the main organ - the heart.

Arterial blood

Based on the above, let us characterize arterial type blood. It ensures the outflow of blood from the heart and carries it to all systems and organs. Its color is bright red.

Arterial blood is saturated with many nutrients; it delivers oxygen to the tissues. Compared to venous, it has highest level glucose, acidity. It flows through the vessels according to the type of pulsation; this can be determined in arteries located close to the surface (wrist, neck).

At arterial bleeding coping with the problem is much more difficult, since blood flows out very quickly, which poses a threat to the patient’s life. Such vessels are located both deep in the tissues and close to the surface of the skin.

Now let's talk about the paths along which arterial and venous blood moves.

Pulmonary circulation

This path is characterized by blood flow from the heart to the lungs, as well as in the opposite direction. Biological fluid from the right ventricle to pulmonary arteries moves to the lungs. At this time, it gives off carbon dioxide and absorbs oxygen. At this stage, the venous vein turns into an arterial vein and flows through the four pulmonary veins into left side heart, namely to the atrium. After these processes, it enters the organs and systems, we can talk about the beginning of a large circle of blood circulation.

Systemic circulation

Oxygenated blood from the lungs enters the left atrium and then into the left ventricle, from which it is pushed into the aorta. This vessel, in turn, is divided into two branches: descending and ascending. The first supplies blood to lower limbs, abdominal and pelvic organs, bottom part chest. The latter nourishes the arms, organs of the neck, upper chest, and brain.

Blood flow disturbance

In some cases, there is poor outflow of venous blood. Such a process can be localized in any organ or part of the body, which will lead to disruption of its functions and the development of corresponding symptoms.

To prevent this pathological condition it is necessary to eat properly, provide the body with at least minimal physical exercise. And if any disorders appear, consult a doctor immediately.

Glucose level determination

In some cases, doctors prescribe a blood test for sugar, but not a capillary one (from a finger), but a venous one. In this case, biological material for research is obtained by venipuncture. The preparation rules are no different.

But the glucose level in venous blood is slightly different from capillary blood and should not exceed 6.1 mmol/l. As a rule, such an analysis is prescribed for the purpose of early detection diabetes mellitus

Venous and arterial blood have fundamental differences. Now you are unlikely to confuse them, but it will not be difficult to identify some disorders using the above material.