Tasks of the white blood cells | Functions of the blood

Tasks of the white blood cells

The white blood cells (leukocytes) serve the immune defence. They are important in the defence against pathogens and also in the development of allergies and autoimmune diseases. There are many subgroups of leukocytes.

The first subgroup is the neutrophilic granulocytes with about 60%. They are able to recognize and absorb pathogens and to kill and digest them by specific substances. However, the granulocytes also die in the process.

The next group are the eosinophil granulocytes with about 3%. They are particularly involved in parasitic diseases (e.g. worms) and allergic reactions of the skin, mucous membranes, lungs and gastrointestinal tract. They also contain substances that are cytotoxic (poisonous) and can thus ward off pathogens.

They also lead to the activation of other immune cells. The third group are the basophilic granulocytes (approx. 1%).

The function of these granulocytes is still relatively unclear. All that is known so far is that they have a receptor for a specific antibody (IgE), which is associated with the development of allergic reactions. Next are the monocytes (6%).

They migrate into the tissue and develop there into so-called macrophages (scavenger cells). These can also absorb and digest pathogens (phagocytosis) and can thus fight various infections. In addition, they can present the fragments of the degraded pathogens on their surface (antigens) and thus enable the lymphocytes (last group) to produce a specific immune response with antibodies.

The last group are the lymphocytes (30%). They can be further divided into natural killer cells and T and B lymphocytes. Natural killer cells recognize infected cells (pathogens) and kill them.

The T- and B-lymphocytes together are able to attack the pathogens specifically. This is done, on the one hand, by the formation of antibodies which then interact with the antigen of a pathogen and thus make it more easily attacked by the immune system. On the other hand, they also form memory cells, so that the immune system can immediately recognize and break down a pathogen on the second contact. Finally, these cells also release substances that kill infected body cells. Only through the interaction of all these cells and specific messenger substances can the immune system function properly and protect the body from pathogens.

Tasks of the thrombocytes

The thrombocytes (blood platelets) are responsible for blood coagulation and hemostasis. If the vessel is injured, the platelets quickly reach the appropriate site and bind to specific receptors of the exposed structures (e.g. collagen). In this way they are activated.

This process is also called primary hemostasis. After activation, the platelets release various ingredients that attract other platelets. The activated platelets form a clot (red thrombus).

In addition, the coagulation cascade in the blood plasma is activated, which leads to the formation of fibrin threads and an insoluble fibrin network. This is also called a white thrombus. In this way, the injuries of the vessel walls are closed very quickly and the bleeding is stopped. If the thrombocyte count is too low, this can lead to nose or gum bleeding or even minor skin bleeding. Even slight injuries can result in bruises or bleeding into internal organs.