“Why do we need immunity?” is not only one of the most popular children’s questions, but also an excellent option for project activities. Especially now, when children and adults “Google” everything related to diseases, viruses and protection against them. In this material, we have collected information that will help both the student and the teacher.
Immunity is the ability of the body to find foreign bodies and substances (antigens) and get rid of them. The word “immunity” comes from the Latin immunitas, which means “getting rid of something”.
Types of immunity
There is a distinction between cellular immunity, in which the destruction of foreign bodies is carried out by cells, for example phagocytes, and humoral immunity, in which foreign bodies are removed with the help of antibodies delivered by blood. Cellular immunity was discovered by I.I. Mechnikov, and humoral immunity was discovered by P. Erlich. The Nobel Prize was awarded to both of them.
Immunity can be specific (a person does not suffer from distemper of dogs). To some foreign bodies, immunity is hereditary (innate), to others it appears after the antigen is detected and identified, and then neutralized (acquired immunity).
How does our body’s immunity work?
The innate immune system has a wide arsenal for meeting and fighting harmful viruses. We will try to explain it “on the fingers”:
Phagocytes – for example, macrophages that “eat” bacteria.
The complement system is a complex complex of protein molecules that can destroy bacteria.
Natural killers (NK-cell) are the very lymphocytes that can introduce substances that destroy it into the bacterium.
Cytokines are signaling protein molecules that transmit information about inflammation or infection in the body.
Antigen-presenting cells (APC) – these cells are able to “expose” peptides that are part of a virus or bacteria. In other words, these are vigilantes who show the violator to the police! APC is a link between two immune subsystems, the second of which is described below.
The adaptive immune system is slower and more complex. But just as smoothly and well!
At the very beginning, the same antigen-presenting cells (APC) are sent with a piece of the pathogen to the lymph nodes, where T-lymphocytes meet them. At the meeting, it turns out that the sample brought by the APC is not a healthy and native part of the body, and therefore T-lymphocytes go into a state of alert, turning into:
In the T-killer, which is able to destroy unhealthy cells of the body.
T helper activates B-lymphocytes. In general, these lymphocytes are able to produce more than 100 million types of antibodies, which is why our body can cope with a huge number of pathogens. But if the virus has mutated, for example, and a new type of SARS has appeared, then the immune system will not be able to do anything about it quickly. Why? Because the body will start all the work anew when it meets with a new subspecies of the aggressor. But to say thank you for the fact that we do not get sick with the same flu twice in a season, it is necessary for B-lymphocytes.