The human immune system protects the body against infections and parasite infestations. It can kill over 99% of all pathogens and intruders before they cause damage to the body. The body uses several lines of defense to do this.
Here you will find further information and selected specialists for diseases of the immune system.
The immune system is the human body's most important defense mechanism . It is mainly responsible for removing microorganisms that have invaded the body. It also transports harmful and foreign substances out of the body. This enables it to prevent permanent damage.
Finally, the immune system is also able to destroy the body's own cells. It generally uses this ability to eliminate defective cells.
In principle, the immune system is not a separate, independent organ. Rather, it is a complex network of various organs, cells and molecules.
The body is constantly exposed to many dangerous environmental influences and hostile microorganisms. If these are not combated, they cause dysfunctional and sometimes even life-threatening diseases.
In addition to bacteria and viruses, many fungi and parasites in particular pose a serious threat to humans.
The immune system fends off pathogens © Bikej Barakus | AdobeStock
Numerous different structures are involved in the immune system. It has several "lines of defense". This allows it to initiate further measures after one line has been breached. Medicine mainly divides these lines of defense into the following categories:
These protective mechanisms are the first line of defense of the immune system. These barriers ensure that many pathogens are unable to enter the body. They can also quickly remove pathogens as soon as they have been intercepted.
Many of these systems are located in the face in particular. The eyes are protected by the eyelids. The mouth is closed by the lips and the nose protects the airways.
The oral cavity also has biochemical defense mechanisms. Saliva, for example, contains the enzyme lysozyme, which is responsible for fighting pathogens.
Many other entrances to the body are also protected by a mucous membrane.
If pathogens are able to overcome these mechanical barriers, they encounter various cells of the immune system that fight them.
Of great importance are, for example
Some of these cells even form specialized organs. These include the lymphatic system.
These cells are mainly formed in the bone marrow.
The cellular components usually circulate in the body's lymphatic channels and blood vessels. This is how they reach the various tissue structures.
Each defence cell is specialized for a specific threat to the body. The cytotoxic T cells, for example, are able to destroy a pathologically altered cell.
The body also uses proteins as messenger substances in the course of a defense reaction. Medicine refers to these as humoral components. This term is derived from the word "humor". In the medical context, it stands for "fluid".
In contrast to the immune cells, these components are not able to move to another location on their own. They merely circulate passively in the bloodstream and lymphatic system to support the immune cells in their fight against a pathogen.
Among other things, the body's plasma cells produce tailor-made antibodies that attach themselves to the invader, thereby deactivating it.
The mechanical and biochemical barriers provide the body with the most effective protection against numerous pathogens. In total, they stop over 99 percent of all
from entering the body and thus prevent infection. Only a few pathogens can overcome the immune system's barriers on their own. Most pathogens overcome them through injuries or previous illnesses, which weakens the immune system.
If the immune system detects pathogens in the body, it initiates an immune response . It primarily distinguishes between an initial infection and a secondary infection.
In the case of an initial infection, the immune system initially only reacts with antigen-presenting cells. These can recognize the typical characteristics of a pathogen and encapsulate it within themselves. This is why medicine also refers to them as phagocytes. Once the phagocytes have completely destroyed the pathogen, they present its individual parts on their surface to the lymphocytes, thereby activating them.
The activated lymphocytes then fight the pathogen with aggressive substances. They also begin to produce antibodies.
Once all the invaders have been successfully combated, so-called memory cells remain in the immune system. These contain all the data collected about the pathogen. This enables a much faster response in the event of a second infection.
During a vaccination, the doctor injects a killed or severely weakened pathogen into the body.
A vaccination supports the immune system. The pathogens, which are usually injected into the bloodstream, cannot seriously damage the body. At most, they trigger a mild illness.
However, the body regards the injected pathogens as fully-fledged pests and takes action against them. In most cases, it has no problems fighting the inoculated pathogens.
By successfully eliminating the pathogen, the immune system is trained to fight the "real" pathogens quickly in future. This has the advantage that even dangerous diseases can no longer harm the body.
Even in the event of an outbreak, the disease is much less severe than with an initial infection.
In an autoimmune disease, the destructive power of the immune system is directed against the body. A healthy immune system is able to distinguish between harmless and dangerous cells. However, allergies and autoimmune diseases cause the immune system's tolerance to fail. From then on, it also targets harmless organisms.
For this reason, the body's own cells are regarded as pathogens and fought by the immune system. This leads to inflammation and the formation of new reactive tissue.
In many cases, permanent damage to the affected organ also occurs.
In Germany, an average of five percent of people suffer from an autoimmune disease. The most common autoimmune diseases are
