Each of these organs and systems is involved in building the immune system and has a specific function. The skin and mucous membranes form the first barrier against pathogens
and protect the body in the best possible way against the penetration of pathogens. On the palatine and pharyngeal tonsils, bacteria that have reached the oral cavity come into contact with immune cells for the first time. The thymus (a gland above the heart) is significantly involved in the development of the immune cells. It ensures, for example, that the lymphocytes are able to differentiate between the body's own cells and foreign cells. The lymphatic system is responsible for the removal of pathogens
In addition, the spleen is an essential component of the immune system: it is responsible for the breakdown of old red blood cells and stores the scavenger cells of the non-specific defence system. It also ensures the multiplication of lymphocytes, which then mature in the thymus. The bone marrow is also decisive for the development of the immune system: both the red and white blood cells
are formed there as well as the blood platelets (thrombocytes) which are decisive for haemostasis or coagulation. From there, the corresponding cells are transferred to other organs responsible for reproduction and maturation and ensure a strong immune system
The intestines and intestinal flora
are also among the most important components of the immune system. Around two thirds of all antibody-forming immune cells are located there and ensure effective defence against foreign invaders. The defence cells of the intestine mark and destroy the pathogens
and store information about foreign cells so that they can react more quickly to them in the future. In addition, bacteria of the intestinal flora ensure that pathogens cannot settle so easily. A healthy intestine
is therefore necessary for a functioning defence system.