How blood clotting occurs in the body. What is the name of the enzyme that causes blood clotting? External and internal pathways of blood coagulation

Blood clotting

Blood coagulation is the most important stage of the hemostasis system, which is responsible for stopping bleeding when the vascular system of the body is damaged. Blood coagulation is preceded by the stage of primary vascular-platelet hemostasis. This primary hemostasis is almost entirely due to vasoconstriction and mechanical occlusion of platelet aggregates at the site of damage to the vascular wall. The characteristic time for primary hemostasis in a healthy person is 1-3 minutes. Blood coagulation (hemocoagulation, coagulation, plasma hemostasis, secondary hemostasis) is a complex biological process of formation of fibrin protein threads in the blood, which polymerizes and forms blood clots, as a result of which the blood loses its fluidity, acquiring a cheesy consistency. Blood clotting in a healthy person occurs locally, at the site of formation of the primary platelet plug. The typical time for the formation of a fibrin clot is about 10 minutes.

Physiology

A fibrin clot produced by adding thrombin to whole blood. Scanning electron microscopy.

The process of hemostasis comes down to the formation of a platelet-fibrin clot. It is conventionally divided into three stages:

1. Temporary (primary) vasospasm;
2. Formation of a platelet plug due to adhesion and aggregation of platelets;
3. Retraction (contraction and compaction) of the platelet plug.

Vascular damage is accompanied by immediate activation of platelets. Adhesion (sticking) of platelets to connective tissue fibers at the edges of the wound is caused by the glycoprotein von Willebrand factor. Simultaneously with adhesion, platelet aggregation occurs: activated platelets attach to damaged tissues and to each other, forming aggregates that block the path to blood loss. A platelet plug appears
From platelets that have undergone adhesion and aggregation, various biologically active substances (ADP, adrenaline, norepinephrine, etc.) are intensely secreted, which lead to secondary, irreversible aggregation. Simultaneously with the release of platelet factors, thrombin is formed, which acts on fibrinogen to form a fibrin network in which individual red and white blood cells get stuck - a so-called platelet-fibrin clot (platelet plug) is formed. Thanks to the contractile protein thrombostenine, platelets are pulled towards each other, the platelet plug contracts and thickens, and its retraction occurs.

Blood clotting process

Classic blood coagulation scheme according to Morawitz (1905)

The process of blood coagulation is predominantly a proenzyme-enzyme cascade in which proenzymes, passing into an active state, acquire the ability to activate other blood coagulation factors. In its simplest form, the blood clotting process can be divided into three phases:

1. the activation phase includes a complex of sequential reactions leading to the formation of prothrombinase and the transition of prothrombin to thrombin;
2. coagulation phase - formation of fibrin from fibrinogen;
3. retraction phase - formation of a dense fibrin clot.

This scheme was described back in 1905 by Morawitz and has not yet lost its relevance.

There has been significant progress in the detailed understanding of blood clotting since 1905. Dozens of new proteins and reactions involved in the blood coagulation process, which has a cascade nature, have been discovered. The complexity of this system is due to the need to regulate this process. A modern representation of the cascade of reactions accompanying blood coagulation is shown in Fig. 2 and 3. Due to the destruction of tissue cells and activation of platelets, phospholipoprotein proteins are released, which, together with plasma factors X a and Va, as well as Ca 2+ ions, form an enzyme complex that activates prothrombin. If the coagulation process begins under the influence of phospholipoproteins released from cells of damaged vessels or connective tissue, we are talking about external blood coagulation system(extrinsic coagulation activation pathway, or tissue factor pathway). The main components of this pathway are 2 proteins: factor VIIa and tissue factor, the complex of these 2 proteins is also called the extrinsic tenase complex.
If initiation occurs under the influence of coagulation factors present in the plasma, the term is used internal coagulation system. The complex of factors IXa and VIIIa that forms on the surface of activated platelets is called intrinsic tenase. Thus, factor X can be activated by both the VIIa-TF complex (extrinsic tenase) and the IXa-VIIIa complex (intrinsic tenase). The external and internal blood coagulation systems complement each other.
During the process of adhesion, the shape of platelets changes - they become rounded cells with spiny processes. Under the influence of ADP (partially released from damaged cells) and adrenaline, the ability of platelets to aggregate increases. At the same time, serotonin, catecholamines and a number of other substances are released from them. Under their influence, the lumen of damaged vessels narrows, and functional ischemia occurs. Eventually the vessels become occluded by a mass of platelets adhering to the edges of the collagen fibers at the edges of the wound.
At this stage of hemostasis, thrombin is formed under the action of tissue thromboplastin. It is he who initiates irreversible platelet aggregation. By reacting with specific receptors in the platelet membrane, thrombin causes phosphorylation of intracellular proteins and the release of Ca 2+ ions.
In the presence of calcium ions in the blood, under the influence of thrombin, polymerization of soluble fibrinogen occurs (see fibrin) and the formation of a structureless network of insoluble fibrin fibers. Starting from this moment, the formed elements of blood begin to be filtered in these threads, creating additional rigidity for the entire system, and after some time forming a platelet-fibrin clot (physiological thrombus), which clogs the rupture site, on the one hand, preventing blood loss, and on the other - blocking the entry of external substances and microorganisms into the blood. Blood clotting is affected by many conditions. For example, cations speed up the process, and anions slow it down. In addition, there are substances that completely block blood clotting (heparin, hirudin, etc.) and activate it (viper poison, feracryl).
Congenital disorders of the blood clotting system are called hemophilia.

Methods for diagnosing blood clotting

The whole variety of clinical tests of the blood coagulation system can be divided into 2 groups: global (integral, general) tests and “local” (specific) tests. Global tests characterize the result of the entire coagulation cascade. They are suitable for diagnosing the general condition of the blood coagulation system and the severity of pathologies, while simultaneously taking into account all the influencing factors. Global methods play a key role at the first stage of diagnosis: they provide an integral picture of the changes occurring in the coagulation system and make it possible to predict the tendency to hyper- or hypocoagulation in general. “Local” tests characterize the result of the work of individual parts of the cascade of the blood coagulation system, as well as individual coagulation factors. They are indispensable for possible clarification of the localization of pathology with an accuracy of the coagulation factor. To obtain a complete picture of the patient's hemostasis, the doctor must be able to choose which test he needs.
Global tests:

• Determination of clotting time of whole blood (Mas-Magro method or Morawitz method)
• Thrombin generation test (thrombin potential, endogenous thrombin potential)

"Local" tests:

• Activated partial thromboplastin time (aPTT)
• Prothrombin time test (or Prothrombin test, INR, PT)
• Highly specialized methods for identifying changes in the concentration of individual factors

All methods that measure the time interval from the moment of adding a reagent (an activator that starts the coagulation process) until the formation of a fibrin clot in the plasma under study belong to clotting methods (from the English “clot” - clot).

see also

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BLOOD CLOTTING- transformation of liquid blood into an elastic clot as a result of the transition of the fibrinogen protein dissolved in the blood plasma into insoluble fibrin when blood flows from a damaged vessel. Fibrin, polymerizing, forms thin threads that hold... ... Natural science. encyclopedic Dictionary

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Blood clotting is a complex system of biological reactions that allows blood to be kept in a liquid state in the vascular bed and stops bleeding through thrombosis. That is, if the integrity of the blood vessels is compromised, a blood clot forms in a short period of time, which closes the wound and stops blood loss. Gradually the wound heals. If the blood clotting process is disrupted under the influence of any factors, then even minor damage can have dangerous consequences.

How does blood clotting occur?

The importance of blood clotting is difficult to overestimate. Thanks to this process, the volume of blood in the body is completely preserved. A change in its consistency occurs under the influence of physicochemical reactions. The main role in this process is played by the protein fibrinogen. When damaged, it turns into insoluble fibrin, which is thin threads. They form a dense network with many cells and delay the loss of blood cells. Thus, a blood clot is formed. Gradually it becomes denser, the edges of the wound tighten, and the healing process begins. Platelets play an important role in the process of thickening a blood clot. Gradually, the wound heals and the fibrin clot dissolves.

Blood clotting consists of three stages:

1. Activation.
2. Coagulation.
3. Retraction.

These steps ultimately trigger processes that cause blood clots to form. Each coagulation factor is important in its own way, but the main ones are proteins. The coagulation process is also impossible without other elements.

Normally, blood has a watery consistency. It consists of a large number of elements completely dissolved in liquid.

And only after receiving damage, mechanisms are launched that lead to blood clotting. The wound becomes clogged, blood cannot flow out, and germs and other substances cannot enter the body.

This process is influenced by various factors.

What influences this process

Of course, it is very important that the blood clots quickly. But at the same time it should not lose its liquid consistency. There are certain diseases in which blood can clot inside the vessels. This process is more dangerous than bleeding.

What affects blood clotting? There are two systems working in the human body. If they work normally, then in the damaged area the blood coagulates, but in the vessels its condition does not change and remains liquid.

The coagulation process is positively influenced by:

• Nervous system. With strong painful stimuli, blood clots faster.
• Conditioned reflexes are also a factor influencing this process.

• When injured, the adrenal glands begin to produce adrenaline, which accelerates blood clotting. It also narrows the lumen of the arteries, which reduces the likelihood of blood loss.
• Vitamin K and calcium salts. They also speed up the clotting process.

If there is another system that prevents blood clotting:

1. The lungs and liver contain heparin. It stops blood clotting and thromboplastin formation. Interestingly, in young people, after physical exercise, the amount of heparin in the body decreases.
2. Protein fibrinolysin. Under its influence, fibrin dissolves.
3. Too much pain can slow down the blood clotting process.
4. In extreme cold, blood may not clot.

Blood clotting is very slow in very young children. This situation continues throughout the first seven days of life. Gradually, the level of prothrombin increases, the state of all coagulation factors returns to normal.

The blood of a child who has reached one year of age will be in almost the same condition as the blood of an adult.

How is blood clotting determined?

There are external and internal stages through which the coagulation process is carried out. The work of factors is activated in cell membranes that have been damaged due to injury.

Under the influence of cations, blood clots faster, and anions slow down this process. The whole system does not work without tissue thromboplastin. All processes must begin one minute after injury.

There is a special method that allows you to determine how quickly blood begins to clot in the human body. The study is called the Mas-Magro clotting time.

It is carried out this way:

• Apply a small amount of Vaseline oil to the watch glass;
• soak cotton wool in alcohol and wipe your finger with it;
• a puncture is made with a disposable needle;
• the blood that has begun to flow out is wiped with a cotton swab and a new drop is squeezed out, it is sucked up with a pipette;
• this pipette is pre-lubricated with paraffin oil;
• the taken material is squeezed onto glass, which has been smeared with petroleum jelly;
• the procedure is repeated until the blood has clotted so much that it cannot be pipetted.

If everything is normal in the human body, then the blood should clot within ten minutes at a temperature of 25ºC. If violations are detected, the necessary treatment is prescribed. If the blood does not clot, then the person has hemophilia. This disease has no cure, but if you monitor your health, you can live with it for a long time.

In addition, there are other methods (according to Sukharev, according to Duka, etc.).

Process violations

Everyone should know why blood clots. After all, violations of this condition can have serious consequences.

Both an increase and a decrease in this process are very dangerous conditions.

Violations can occur for the following reasons:

• use of certain drugs;
• genetic mutations such as hemophilia;
• disorders under the influence of concomitant diseases such as a lack of vitamin K in the body or liver pathologies.

Reduced coagulability at any stage is dangerous. It can cause internal bleeding. Most often, the “provocateur” is a stomach ulcer. In this case, it is necessary to take action as quickly as possible. Increased clotting may have even more consequences.

Depending on the stage of the disease, the following consequences are possible:

1. A blood clot may break off. Blood clots are called thrombi. This is the most dangerous consequence of disorders of the coagulation system. Even small blood clots can lead to circulatory problems, and if a vessel is blocked, it can be fatal. An injury or certain medications can cause a blood clot to break off. The most dangerous thing is if a blood clot clogs the pulmonary artery. This complication most often ends in the death of the patient.
2. Thrombophlebitis. In this case, blood clots are located on the walls of blood vessels and clog the lumen. Because of this, certain areas of the body suffer from insufficient blood supply.
3. Increased clotting can lead to irreversible damage to the heart and brain. A specialist can tell you in more detail what this is.

Everyone should know what influences blood clotting in order to prevent complications in time in case of violations.

The main fluid of the human body, blood, is characterized by a number of properties that are of utmost importance for the life of all organs and systems. One of these parameters is blood clotting, which characterizes the body’s ability to prevent large blood losses when the integrity of blood vessels is disrupted by the formation of clots or thrombi.

How does blood clotting occur?

The value of blood lies in its unique ability to deliver nutrition and oxygen to all organs, ensure their interaction, and evacuate waste waste and toxins from the body. Therefore, even a small loss of blood becomes a health threat. The transition of blood from a liquid to a jelly-like state, that is, hemocoagulation begins with a physicochemical change in the composition of the blood, namely, with the transformation of fibrinogen dissolved in plasma.

What substance is dominant in the formation of blood clots? Damage to blood vessels is a signal specifically for fibrinogen, which begins to transform, turning into insoluble fibrin in the form of threads. These threads, intertwined, form a dense network, the cells of which retain the formed elements of the blood, creating an insoluble plasma protein that forms a blood clot.

Subsequently, the wound closes, the clot becomes denser due to the intensive work of platelets, the edges of the wound are tightened and the danger is neutralized. The clear yellowish liquid released when a blood clot hardens is called serum.

To more clearly imagine this process, we can recall the method for producing cottage cheese: coagulation of the milk protein casein also contributes to the formation of whey. Over time, the wound resolves due to the gradual dissolution of fibrin clots in nearby tissues.

Blood clots or clots formed during this process are divided into 3 types:

• White thrombus formed from platelets and fibrin. Appears in injuries with high blood flow, mainly in arteries. It is called so because the blood clot contains trace amounts of red blood cells.
• Disseminated fibrin deposits form in very small vessels, capillaries.
• Red blood clot. Clotted blood appears only in the absence of damage to the vascular wall, with slow blood flow.

What is involved in the clotting mechanism?

The most important role in the coagulation mechanism belongs to enzymes. This was first noticed in 1861, and a conclusion was made that the process could not occur in the absence of enzymes, namely thrombin. Since coagulation is associated with the transition of fibrinogen dissolved in plasma into the insoluble protein fibrin, this substance is the main one in the coagulation process.

Each of us has thrombin in a small amount in an inactive state. Its other name is prothrombin. It is synthesized by the liver, interacts with thromboplastin and calcium salts, turning into active thrombin. Calcium ions are present in the blood plasma, and thromboplastin is a product of the destruction of platelets and other cells.

To prevent the reaction from slowing down or not completing, the presence of the most important enzymes and proteins is necessary in a certain concentration. For example, the well-known genetic disease hemophilia, in which a person is debilitated by bleeding and can lose a dangerous amount of blood due to one scratch, is due to the fact that the blood globulin involved in the process does not cope with its task due to insufficient concentration.

Why does blood clot in damaged vessels?

The process of blood clotting consists of three phases passing into each other:

• The first phase is the formation of thromboplastin. It is he who receives the signal from damaged vessels and triggers the reaction. This is the most difficult stage due to the complex structure of thromboplastin.
• Conversion of the inactive enzyme prothrombin into active thrombin.
• The final phase. This stage ends the formation of a blood clot. Thrombin acts on fibrinogen with the participation of calcium ions, resulting in fibrin (an insoluble thread-like protein), which closes the wound. Calcium ions and thrombostenin protein compact and secure the clot, resulting in retraction of the clot (reduction) by almost half in a few hours. Subsequently, the wound is replaced with connective tissue.

The cascade process of thrombus formation is quite complex, since a huge number of different proteins and enzymes are involved in coagulation. These necessary cells (proteins and enzymes) involved in the process are blood coagulation factors, a total of 35 of them are known, of which 22 are platelet and 13 are plasma.

Factors contained in plasma are usually designated by Roman numerals, and platelet factors by Arabic numerals. In the normal state, all these factors are present in the body in an inactive state, and with vascular damage, the process of their rapid activation begins, resulting in hemostasis, that is, stopping bleeding.

Plasma factors are protein in nature and are activated during vascular damage. They are divided into 2 groups:

• Dependent on vitamin K and produced only in the liver;
• Vitamin K independent.

Factors can also be found in leukocytes and erythrocytes, which determines the enormous physiological role of these cells in blood coagulation.

Clotting factors exist not only in the blood, but also in other tissues. The thromboplastin factor is contained in large quantities in the cerebral cortex, placenta, and lungs.

Platelet factors perform the following tasks in the body:

Blood clotting normal over time

One of the main blood indicators is a coagulogram - a study that determines the quality of clotting. The doctor will always refer you for this study if the patient has thrombosis, autoimmune disorders, varicose veins, acute and chronic bleeding of unclear etiology. This analysis is also needed for necessary cases during surgery and pregnancy.

The blood clot test is performed by drawing blood from a finger and measuring how long it takes for the bleeding to stop. The coagulation rate is 3-4 minutes. After 6 minutes it should already be a gelatinous clot. If blood is extracted from the capillaries, a clot should form within 2 minutes.

Children have faster blood clotting than adults: the blood stops after 1.2 minutes, and a blood clot forms after only 2.5-5 minutes.

Also important when testing blood are the following measurements:

Under what conditions is equilibrium between two inverse systems maintained?

In the human body, two systems operate simultaneously to ensure coagulation processes: one organizes the rapid onset of thrombus formation in order to reduce blood loss to zero, while the other in every possible way prevents this and helps maintain the blood in the liquid phase. Often, with certain health problems, pathological blood clotting occurs inside intact vessels, which is a great danger, significantly exceeding the danger from bleeding. For this reason, thrombosis of the blood vessels of the brain, pulmonary artery and other diseases occur.

It is important that both of these systems work correctly and are in a state of intravital equilibrium, in which the blood will coagulate only when the vessels are damaged, and inside the undamaged ones will remain liquid.

Factors that cause blood to clot faster

• Painful irritations.
• Nervous excitement, stress.
• Intensive production of adrenaline by the adrenal glands.
• Increased levels of vitamin K in the blood.
• Calcium salts.
• Heat. It is known at what temperature a person’s blood clots – at 42 degrees C.

Factors that prevent blood clotting

If you suspect poor blood clotting, it is important to identify the causes of the situation, eliminating the risks of severe disorders.

The speed of blood clotting is of great importance for stopping bleeding that occurs after a violation of the integrity of the vessels and tissues of the body: the blood flows until a plug of a blood clot forms. This mechanism of blood clotting is explained by its ability to thicken, that is, to form a dense structure when wounds appear. Once the wound healing process is complete, the blood clot will naturally dissolve.

Thus, if the blood clot forms too slowly, it will cause the person to lose a large amount of blood with the smallest scratch. But increased blood clotting is also dangerous, as it leads to the formation of blood clots in the blood vessels.

Blood coagulation is a very complex process in which, in order to stop blood loss, a huge number of elements circulating in the blood are simultaneously started. That is why the speed of clot formation is directly influenced by the quality of the coagulation system. The reasons that negatively affect blood clotting can be divided into three groups:

• Hereditary mutations that occur in genes. Changes in genes can lead to blood diseases such as hemophilia. This disease is extremely dangerous: back in the 60s of the last century, the average life expectancy of a person with a gene mutation that caused hemophilia rarely exceeded eleven years. But already in the 80s. people with mutations in genes lived to be sixty. Nowadays, this disease is successfully treated with drug therapy.

• Physiological reasons are processes, the essence of which is that the formation of a clot is influenced by liver disease, bleeding, vitamin K deficiency and others.

• The use of certain medications, which include anti-inflammatory drugs, blood thinners, aspirin, anticoagulants.

Increased blood clotting often occurs due to thickening of fluid tissue. This leads to slower blood flow and increased blood clot formation. This situation is dangerous because a blood clot can clog a vessel. If it turns out to be a central artery or vein, death is possible.

The cause of thickening may be dehydration due to diarrhea and vomiting. Disseminated intravascular coagulation (DIC) also causes fluid tissue to clot in the blood vessels, forming microthrombi.

In addition to the fact that impaired blood flow leads to thrombus formation, degenerative changes are observed in the body. This syndrome can occur in various diseases, which determine the speed and strength of its spread: from sluggish chronic conditions to acute lesions with a fatal outcome.

Low blood clotting is also dangerous because wounds and injuries heal very slowly. It is very important for your doctor to know this before surgery. This will help prevent bleeding and save the patient's life. Also, reduced coagulability can cause bleeding in the gastrointestinal tract if the patient has an ulcer. This is another reason on which the need to examine patients before prescribing the correct doses of anticoagulants depends.

The importance of balance

The process of blood clotting has been the subject of intensive study over the past decades. The very essence of the concept of “blood coagulation system” has been subject to repeated revision.

Many researchers adhere to the traditional opinion that the coagulation system is divided into an internal and an external pathway. Therefore, there is such a thing as the normal or usual path of the blood coagulation system.

This is explained as follows: the coagulation system maintains its functioning through self-regulation, which takes an active part in maintaining the structure of liquid tissue. The concept of “normal coagulation pathway” is a balance between the mechanisms of coagulation and anticoagulation, which is part of the anticoagulation system of the blood. When the balance between the coagulation and anticoagulation systems is disturbed, increased formation of blood clots or bleeding is observed.

Interaction of blood components

The biochemical theory of blood coagulation is associated with the concept of a cascade. A coagulation cascade is a blood coagulation pattern that reflects the interaction of different components of liquid tissue (also called blood factors) that circulate in the plasma in an inactive state until a vessel ruptures. When this happens, processes begin one after another in the body aimed at eliminating the breakthrough.

At the beginning of the cascade, thromboplastin is formed, which is preceded by two phases of blood coagulation. These are also known as the two coagulation pathways – internal and external.

Previously, both paths of the cascade, internal and external, were given equal importance. It is now known that the external (tissue) pathway of the cascade is primary. At the end of the cascade, when the chain of enzymatic changes in coagulation reactions ends, fibrin appears. Each reaction that occurs in the cascade transforms a proenzyme into an enzyme.

The coagulation cascade is regulated by the following restraining mechanisms:

• Protein C is one of the most powerful factors in the anticoagulant system. This is an enzyme that activates thrombin. The activated form of protein C, together with protein S and phospholipids as cofactors (the so-called non-protein compounds that bind to proteins), inhibits coagulation factors Va and VIIa. A deficiency of proteins C and S can lead to thrombophilia.

• Antithrombin is a protein that inhibits serine protease proteins: thrombin, factors IXa, Xa, XIa, XIIa.

• Tissue factor inhibitor (TFPI) inhibits factors VII and X.

• Plasmin is a protein produced in the liver that destroys fibrin.

• Prostacyclin - inhibits platelet activity, reducing the level of calcium ions.

According to statistics, coagulation factor VII increases the likelihood of death from a heart attack. But on the other hand, in some people, factor VII reduces the risk of thromboembolism and myocardial infarction. Polymorphisms are caused by gene mutations where guanine is replaced by adenine, causing arginine to replace glutamine in the factor VII structure. According to statistics, factor VII polymorphisms are found in 10-20% of the population.

What is blood factor?

Blood clotting factors are of great importance in the process of blood clot formation. Typically these are enzymes that are produced in the liver, spleen and some other organs. When vascular damage occurs, blood factors trigger the processes necessary to block the breakthrough.

The theory explaining blood clotting as a chain of enzymatic reactions was formulated in the 18th century by H.Y. Schmidt. The main stages of the coagulation process were named:

• Conversion of prothrombin to thrombin.
• Thrombin activates the conversion of fibrinogen to fibrin.

To complete these stages, the presence of calcium ions is necessary. Currently, this theory has been developed and supplemented by the discovery of many additional factors.

Factor VII and ADP

There are thirteen factors in total, which are designated by Roman numerals. Blood coagulation factor VIII is one of the most important, so its amount in liquid tissue helps diagnose hemophilia. In the coagulation cascade, factor VII reacts with factor III, converting factors IX and X into an active state. In other words, it takes an active part in the formation of a blood clot.

Inherited mutations in genetic material can cause clotting factor VIII to have a defective structure. This increases the risk of hemophilia.

Another factor that affects the activation of platelets and the enhancement of their thrombus-forming activity is ADP. This enzyme is released during the destruction of red blood cells.

Increased breakdown of red blood cells or hemolysis occurs in many inflammatory diseases, infectious infections, transfusion of Rh-incompatible blood, mismatch of blood groups of mother and fetus. The breakdown products of erythrocytes enhance the aggregation and adhesion of platelets, which can cause intravascular coagulation.

The immediate result of the destruction of red blood cells is anemia. In pathological hemolysis, when a significant number of red blood cells are destroyed, a significant amount of bilirubin is produced. As a result, an increased amount of this pigment is observed in the urine and a small amount in the feces (usually vice versa).

Importance of Analysis

Coagulation consists of many phases, so the blood test must take into account all known factors involved in this chain. Diagnostics aimed at determining in which link the functioning of which factor is impaired increases the accuracy of the diagnosis and facilitates the appointment of appropriate treatment.

A test such as the activated partial thromboplastin time allows us to assess the patient's tendency to internal bleeding. It allows you to understand the role of tissue factor in the coagulation process, test the functioning of the liver, and identify vitamin K deficiency.

A blood test for D-dimer (a fibrin breakdown product that is formed after the destruction of a blood clot) is important during surgical operations and during pregnancy, since it allows you to assess the condition of the cardiovascular system. Thus, correct diagnosis of blood clotting helps reduce the risk of complications and death in severe illnesses, during operations and childbirth. A blood clotting test makes it possible to obtain a reliable guarantee of safety against negative consequences that can provoke a clotting disorder.

The materials are published for informational purposes only and are not a prescription for treatment! We recommend that you consult a hematologist at your medical institution!

Normal blood clotting is very important to ensure the coordinated functioning of all internal organs. The biosystem that directly determines the optimal level of blood clotting is hemostasis. It is responsible for two functions of our body: it maintains the blood in a liquid state or clots it if there is any damage to the blood vessels. The appropriate analysis allows you to determine how correct the functioning of a given system is.

Features of hemostasis

The hemostasis system regulates blood loss in the body through two mechanisms:

1. Vascular-platelet hemostasis;
2. Coagulation hemostasis.

The first of them prevents clotting, and the second is responsible for direct blood clotting. Working independently of each other, but at the same time, these two mechanisms make it possible to ensure a proper balance of blood coagulation, that is, to protect the body from decreased or increased coagulation.

The consistency of the blood should be stable. For good circulation through the vessels, it must be sufficiently fluid. But in order not to leak through the walls of blood vessels under pressure, the blood must be thick enough.

Important! If a vessel is damaged, the body forms a blood clot in this place, preventing blood from flowing out. In a healthy body, a local course of this process is observed, that is, a blood clot forms specifically at the site of damage to the vessel wall. If the blood has poor clotting properties, the blood clot forms slowly. With an increased coagulation rate, on the contrary, the process occurs quickly.

The following factors may affect blood clotting time:

• The state in which the vascular walls are located. Increased clotting can occur if the structure of the artery walls is seriously damaged.
• Plasma factor concentration. For the most part, they are synthesized by the liver. These factors that influence coagulation can be of reduced or increased levels, which directly affects blood clotting.
• Anticoagulation system and plasma factor concentrations. The more of these factors, the thinner the blood will be.
• The number of platelets, as well as the usefulness of their functioning. It is platelets that “monitor” the integrity of blood vessels and provoke the process of blood clotting.

There are three stages of clotting, and if any of them occurs incorrectly, then the entire clotting function can be disrupted.

Importance of analysis to determine the level of coagulation

A blood clotting test is one of the key studies before any type of surgery or during pregnancy. The blood clotting time has been scientifically established: the norm for women and men is from one to five minutes. The main objective of this analysis is to determine the results of blood clotting when the vessels are damaged. Possible diseases are also checked - the presence of various blood pathologies, both congenital and acquired, is established.

Video about blood clotting

Blood clots that form on the walls of the human vascular system are the most common causes of stroke, coronary artery disease, and heart attack. At the same time, the main causes of thrombosis lie precisely in the increased level of coagulation, which leads to the formation of blood clots.

Important! It is imperative to check blood clotting in a timely manner, because its elevated level can cause a number of diseases of the cardiac and vascular systems. Also, a violation of blood clotting properties often occurs against the background of serious pathologies, and therefore this analysis can become an important stage in the diagnosis of various diseases that can even have irreversible consequences, including death.

A test for blood protein coagulation should be carried out to prevent possible disruptions in the hemostasis biosystem in the following patients:

• Persons who have reached the age of forty.
• Pregnant women, since hemostasis during pregnancy can change significantly.
• During menopause.
• Anyone preparing for surgery.
• Patients who have been taking medications and products that thin the blood for a long time.

Features of the analysis

Now let's figure out how to take a clotting test. Blood is drawn from a vein, after which it is sent into a test tube, into which an anti-clotting substance is then added. After this, a number of samples are taken, which determine 8 analysis parameters, the main of which are:

• Internal way to stop bleeding.
• Clot formation time.
• External pathway of blood clotting.

The scheme for determining blood clotting involves 5 more parameters, which are classified as additional.

Causes of development of blood clotting abnormalities

Any deviations from normal blood clotting are undesirable. There are such types of disorders in this case: increased and low coagulability. When this indicator increases, blood clots may occur, as a result of which the blood supply to individual organs decreases or even stops altogether. Moreover, such disorders can be either congenital or acquired.

The most common reasons for such deviations are:

• The patient is taking anti-inflammatory drugs, anticoagulants, fibrinolytics and aspirin.

• Gene mutations, which can also be inherited (hemophilia).
• Lack of vitamin K in the body, blood and liver diseases, excessive blood loss.

Important! Poor clotting requires immediate treatment.

Causes and consequences of increased blood clotting

In this case, the likelihood of blood clots in the vascular system and inflammation of the veins increases significantly, which ultimately leads to the development of thrombophlebitis. The main signs of this pathology are the appearance of swelling in the area of ​​the affected veins, redness of the skin with pain.

They lead to disruption of blood flow in tissues, clogging blood vessels. Thus, tissue damage occurs in the unhealthy area. If there is a complete blockage of blood flow to an organ, an area appears where cells die (ischemic focus), this leads to disruption of the functioning of the organ, which is fraught with irreversible consequences.

Important! Increased coagulability poses the greatest danger to the brain and heart, since their damage often leads to disability and even death.

The most terrible complication of thrombophlebitis is the detachment of a blood clot. If the thrombus is diametrically smaller than the vessel, then it begins to move along with the blood until it clogs one of the vessels. The greatest danger to the patient's life is thromboembolism that occurs in the pulmonary artery. To avoid such consequences, blood clotting should be carefully checked.

There are a number of reasons that determine increased clotting. Here are the most common of them:

This disease poses a serious danger to patients, as bleeding may occur. It often occurs in those who suffer from ulcers (in the stomach or intestines). This can lead to significant blood loss.

Important! With poor blood clotting, the risk that bleeding will open inside the organ increases significantly. Such manifestations are often noticed by specialists too late. For this reason, a clotting test should be carried out even with a simple tooth extraction.

Patients with poor coagulability usually experience bleeding gums, nosebleeds are possible, and bruises occur even with minor blows or injuries. Protruding bruises may be large or resemble a rash in nature. Patients may also develop cracks or wounds on the skin without any obvious reason.

Poor blood clotting may have symptoms similar to anemia, such as:

• hair loss;
• general malaise;
• brittle nails;
• dizziness;
• diarrhea or, on the contrary, constipation, etc.

Poor blood clotting may indicate that the patient has a serious disease such as hemophilia, which causes a tendency to bleed. This disease can be inherited through the male line, despite the fact that its carriers are women.

Problems with clotting can occur due to poor environmental conditions, work in hazardous conditions, decreased immunity, or the development of cancer.

Any abnormalities in blood clotting are not only dangerous for the patient’s life, but may also indicate the development of a number of serious diseases in his body. For this reason, you should immediately consult a doctor if you notice one of the above symptoms.