What is the immune system?

We explain what the immune system is and what function it performs. In addition, how it is shaped and what diseases compromise it.

1. What is the immune system?

It is known as an immune system, immune system or immune system to a defensive mechanism of the human body and other living beings , which allows, through coordinated physical, chemical and cellular reactions, to keep the organism free of foreign and potentially harmful agents, as they can be toxins, poisons, or viral, bacterial and other microorganism infections.

Such bodies and foreign elements to the organism are called antigens , and their presence in the organism triggers a highly specialized reaction to prevent it from spreading or remaining in the body. This reaction, called antigen-antibody , consists mainly in the segregation of cells and defensive substances, such as the different types of white blood cells ( antibodies ), whose mission is to recognize and expel invaders from the body.

However, the immune system also has mechanical or physical strategies that include inflammation of the affected area (as an isolation method ), increased body temperature or fever (to make the body less hospitable to invaders), and others specialized answers.

The immune system is composed of various cells and organs of the body , especially the organs and glands that produce white blood cells, but also a whole series of mucous membranes and insulating barriers to prevent the entry of foreign elements. In any case, when defending the organism, many other systems collaborate or are affected by the functioning of the body’s defenses.

2. Immune system function

The immune system operates based on its two variants: the natural and acquired or learned immune system:

• Natural immune system . Also called innate or non-specific immune system, it is born with individuals as it consists of defense mechanisms typical of the chemistry of life. It is common to a greater or lesser extent to almost all living beings, even the simplest and unicellular forms, but they are capable of dealing with invaders by secreting enzymes and defensive proteins .
• Acquired immune system . Exclusive to vertebrates and more complex living beings , it has cells totally dedicated to the defense and cleaning of the organism, highly specialized in its task. Its name comes from the fact that it adapts and has a cellular “memory” to recognize the infectious agents with which it has already fought, so that it can deal better with them in the future. That is what vaccines are worth: they provide attenuated microbes so you can feed your memory without first having to suffer the disease.

3. How is the immune system formed?

The immune system is composed of a network of white blood cells that travels through the body and that has presence in both the blood, bone marrow and other substances of the body , as well as the lymphatic system used to move along the ganglia and organs of body filtering, such as the spleen.

These white blood cells can be of two types:

• Lymphocytes . They are responsible for detecting and recognizing foreign bodies, as well as learning their characteristics to add them to the immunological memory, to recognize them in case they re-enter the body.
• Phagocytes . Those in charge of dealing with foreign bodies, that is, doing dirty work: phagocytize (encompass inside) the invaders and then expel the organism with them inside, through urine, feces, mucus or other secretions

4. Immune system diseases

Despite the extraordinary immune system, it is not always 100% effective. In many cases, in fact, its operation is compromised and requires the incorporation of medications. These cases are:

• Allergies , which are nothing more than a disproportionate reaction of the immune system, which responds to the presence of a harmless substance as if it were an attacker.
• Autoimmune diseases , in which the immune system becomes the problem , because it attacks healthy cells or tissues and the body itself, identifying them by mistake as infected or as foreign.
• Immunosuppressive diseases , such as AIDS, whose infectious agents just attack white blood cells responsible for defense, through various strategies that do not allow their capture and ordinary expulsion. As a result of these diseases, people become immunosuppressed (that is, without defenses) and other opportunistic diseases can take advantage of that condition.