The immune system, or immune system in medical terms, defends you against millions of foreign and harmful microbes and substances that can make you sick.
It has the ability to recognize and differentiate between the millions of different foreign enemies that enter our bodies. If you are healthy, it fights against enemies, often “unbeknownst” to you, and you don’t even realize it is working. In summary, the immune system is the defense system that protects our body from the damaging effects of foreign substances and microbes.
There are small cells in our blood vessels that are invisible to the eye, mostly red blood cells (erythrocytes) that give our blood its red color, and a smaller number of white blood cells (leukocytes).
These cells are made in the bone marrow. The main organs of the immune system are the bone marrow and the thymus. The bone marrow is a fatty, porous structure in the center of the bones that produces stem cells that make red and white blood cells.
B and T lymphocytes, which are single nucleated white blood cells, are the main cells in the immune system. B lymphocytes develop in the bone marrow and T lymphocytes in the thymus, a tissue in the upper chest.
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Neutrophils and macrophages gather around every germ or substance that enters our body, recognize it as foreign, swallow it and destroy it with the enzymes they secrete. Similarly, tissue macrophages in each of our organs perform the same task.
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Eosinophils and basophils are responsible for the development of allergic diseases. Eosinophils also destroy parasites that enter our bodies. Natural killer (NK) cells attack the microbe or cell that they recognize as foreign without the use of any intermediaries and kill it by making holes in the surface of the cell with the enzymes they secrete.
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The dendritic cells have many appendages like tree branches, they capture the microbe that enters our body, break it down and then present it to the T-helper cells, leaving it to the T cell to destroy it. Lymphocytes Lymphocytes that proliferate in the thymus are called T-lymphocytes and lymphocytes produced in the bone marrow are called B-lymphocytes. After they complete their development, they begin to circulate in the blood and lymph system.
How does the immune system or immune system work?
Mechanical, chemical and biological barriers form the first shield against microbes entering our body. If the microbe overcomes the barriers and enters the body, the innate ‘innate immune system’ that meets and recognizes the microbe in the first step is activated in a very short time. The cells of this system, white blood cells (neutrophils, macrophages, natural killer (NK) cells), the building blocks of the complement system in protein structure and cytokines that provide intercellular communication accumulate at the site of entry into the body, attack the foreign microbe and destroy it. Natural killer (NK) cells kill the cell by puncturing holes in its membrane. This prevents the microbe from spreading throughout the body. The innate immune system fights the same fight against every microbe and every stranger. If the germ is still multiplying, B lymphocytes and T cells, the cells of the ‘acquired immune system’, take part in the defense. B cells start to produce antibodies against the germ with the help of T cells, and T killer cells destroy the infected cells. This defense lasts 15-30 days. At the end of the defense, the immune system stores the germ in its memory. When the immune system encounters the same microbe again months or years later, it remembers the microbe and takes action within 2-3 days to protect the person from the disease. The B cell makes antibodies specific for each microbe. A child who has been infected with the measles virus or vaccinated with the measles vaccine will not get sick when exposed to the measles germ, because the person who has been infected or vaccinated has protective IgG antibodies in their blood.
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