2024-03-01 19:26:58
Thrombocytes, also known as blood platelets, are among the smallest cells in human blood and are primarily responsible for blood clotting.
Here you will find all information about the functioning, values and diseases of the vital blood cells. The German zoologist and anatomist Max Johann Sigismund Schultze was the first to describe platelets.
In 1865 he published the article on microscopic anatomy. The formation, function and mode of action of blood cells have always been continuously researched.
In addition to leukocytes, white blood cells, and erythrocytes, red blood cells, platelets play an essential role in the organism.
The platelet as a sentinel cell and important blood clot
The blood cells neither have a cell nucleus nor do they contain valuable genetic information, also known as DNA, and have important functions in the organism.
They are an important element in blood clotting and hemostasis. As soon as a bleeding wound is caused by a cut, the blood platelets attach to the open tissue to close the open injury.
This reaction can be observed in everyday life. The blood collects directly on and around the edges of the wound, forming a bloody plug. The substances in the blood that promote clotting are responsible for the fact that the blood is relatively thick at this point and then dries out.
The attachment of the surrounding tissue is medically called platelet adhesion, while the attachment of the surrounding tissue is called platelet aggregation.
Current topics:
Platelets: definition
Function, formation, appearance and breakdown of blood platelets
According to their definition, platelets are rounded, flat components of the blood that play an important role in blood clotting. Detailed information about the thrombocytes known as platelets and their definition follows. The definition of platelets includes explanations of their origin, their appearance, their function and the normal values.
Definition based on the origin of the word “platelets”
When defining platelets, it makes sense to start with their names. The word thrombocyte comes from ancient Greek and is made up of two parts. The first word “thrómbos” translated into German means “lump”, whereas the ancient Greek “kýtos” means “cover” or “vessel”.
The name illustrates the important role of platelets in blood clotting. Accordingly, the platelets stop bleeding by forming a clot. This creates a sheath around the injured area of the affected vessel.
Formation of platelets in the bone marrow
The blood platelets originate in the bone marrow before they enter the blood. They arise from contractions of megakaryocytes. These are large cells of the bone marrow. Each of the associated cells produces up to 8,000 platelets during its lifespan. The process described is called thrombopoiesis and requires a hormone called thrombopoietin.
Shape, size and lifespan of platelets
With their flat, rounded shape, the platelets have a diameter of 1.5 to 3.0 micrometers. They are therefore considered the smallest components of the blood. According to the thrombocyte definition, blood platelets do not have a cell nucleus. Nevertheless, they have a limited ability to synthesize proteins. The lifespan of platelets is an average of ten days. The blood platelets that are no longer needed are then broken down in the spleen and lungs. The liver also helps break down platelets.
How platelets stop bleeding
Platelets play an important role in blood clotting in the human body. In this regard, the platelets help to stop bleeding and seal the vessels. If a blood vessel is injured, messenger substances inform the platelets. The latter then change their shape and pseudopodia protrude. This enables a significant increase in surface area.
The platelets attach to the injured area of the vessel and connect with each other using fibrin. This creates a clot or lump, known in technical terms as a “thrombus,” which closes the area and stops the bleeding. In technical terms, the process is called platelet aggregation.
Reference values of platelets in children and adults
A definition of platelets also includes information on the reference values of blood platelets. A healthy body has the following values per microliter of blood:
• five to 15 years: 250,000 to 440,000
• adults: 150,000 to 380,000
As a result, children have more platelets in a microliter of blood than adults.
Definition of the technical terms for increased and decreased platelet levels in the blood
Sometimes there are upward or downward deviations in the values mentioned. Such fluctuations have various causes. Blood platelet levels that are too low are due to reduced formation or a shortened lifespan of platelets.
If the blood platelet concentration is significantly reduced, there is a significant blood clotting disorder. Patients tend to have severe bruising, bleeding from the nose or gums, and anemia. In the opposite situation, too high platelet levels increase the risk of thrombosis or embolism.
Medical terminology has definitions for the platelet deviations described. If a patient has too few blood platelets, doctors speak of thrombocytopenia. If they detect increased concentrations in the blood, this is a so-called thrombocytosis.
Summary of definitions of task, appearance and associated diseases
In summary, according to the definition explained, platelets are the smallest components of the blood. According to their name, when bleeding occurs, they form a lump in the open area. The platelets connect via fibrin and form a coating that stops bleeding.
On average, platelets live ten days before the spleen, lungs and liver start breaking them down. If the body has too few blood platelets, this is called thrombocytopenia. In the opposite case of increased values, medicine uses the technical term thrombocytosis.
Pathological changes in platelets
In rare cases, diseases caused by a permanent lack of platelets are observed. These diseases, which are based on too low production, are called thrombocytopenias; the increased production is thrombocytosis.
Since the blood particles are also produced in the bone marrow, damage or pathological changes to the bone marrow can also lead to under- or overproduction.
Diseases associated with permanent deficiency include Jacobsen syndrome, Gray Platelet syndrome, TAT syndrome, Gaucher disease and TAR syndrome. However, they are currently rarely observed.
Over-the-counter medications that contain blood-thinning substances can lead to undesirable blood thinning if taken long-term and can significantly impair functionality. Such medications can cause increased nosebleeds or prolonged periods.
Polycythämie
Polycythemia vera can also be a possible cause. This disease affects the blood-forming cells. The overproduction of red blood cells, called erythrocytes, also increases production and thrombocytosis can occur.
Thrombocythemia
But there is also the possibility that thrombocythemia is present. This disease also involves the disease of blood-forming cells. Here too, increased blood platelets are formed.
However, thrombocythemia is only considered when the concentration of platelets is far above the norm and there are over 600,000 G per ml in the blood. Most of the time, the affected person does not even notice the illness. However, there may be an increased risk of bleeding coupled with thromboembolic complications. Before treatment, the doctor must always define the causes and thus the distinction between reactive thrombocytosis and secondary thrombocytosis caused by bone marrow cell disease.
Thrombopoese
Platelets are largely formed in the bone marrow, but also in the capillaries of the lungs and in the peripheral blood. During this process, the platelet-forming cells, the megakaryocytes, contract.
In this process, up to around 8,000 individual blood platelets can be formed from a single bone marrow cell over the course of a lifetime. In addition, the hormone thrombopoietin supports the process of platelet formation. The entire process is called thrombopoiesis.
Interestingly, new platelets can also form in blood reserves or stored blood samples. On the other hand, there is currently no reliable knowledge as to whether blood platelets are generally formed in the bloodstream itself. The assumption that these important blood platelets can also develop independently in the body would result in new possibilities for the treatment of blood clotting disorders.
When are laboratory values determined?
A targeted determination of the values is usually not carried out. An assessment should only be made in people who observe that wounds bleed more heavily and for longer than usual.
In addition, the number of platelets is checked in every routine blood count. The situation is different for patients who receive heparin-based blood thinning medications; regular checks must be carried out here. Thrombosis patients also need their values checked.
Furthermore, people who suffer from acute or aplastic anemia, for example, belong to the risk group for low values, for which mandatory monitoring is essential. A general viral infection, chronic inflammation of the liver, liver cirrhosis or regular alcohol abuse are also common causes of low values.
Elevated values, on the other hand, occur primarily in acute infections, in chronic inflammations, in tumor diseases and usually only temporarily after the surgical removal of the spleen. When the bone marrow itself produces too many blood cells, it is generally referred to as essential thrombocythemia.
Sources and additional pages:
- Basic knowledge of immunology, Stefan H. Kaufmann, SE Coupland et al. Lymphatic system and differentiation of B and T lymphocytes
1709325715
#Platelets