O immune system, also called the immune system, it is what guarantees our body protection, preventing foreign and pathogens negatively affect our health. It is a complex system that involves a series of cells and bodies that work together as a great protective barrier.
Our body's ability to protect us against these agents is called immunity. Immunity can be classified as innate and acquired. The first presents a broader response, and individuals are born with the mechanisms that promote it. In the second, the answers are more specific, and the individual develops them during their lifetime.
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Immune system
The immune or immune system is made up of different cells, fabrics, organs and molecules. In this system we have individualized structures, such as the spleen and lymph nodes, and free cells, such as leukocytes.
It guarantees the recognition of cells and foreign substances and the destruction or neutralization of invaders
, thanks to a coordinated response of its components. This response is essential to ensure that the body develops or not a disease or even the duration of it.The immune system is capable of differentiate the body's own cells from invaders, which guarantees great efficiency in the body's defense. However, in some situations, he can react against our own body, triggering autoimmune diseases.
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Leukocytes
When we talk about cells that participate in the immune system, we must emphasize leukocytes, responsible for the main defense actions of the organism. Also called White blood cells, are produced in the bone marrow and migrate to various parts of the body by blood vessels. When the bone marrow produces too few white blood cells, we have a condition known as leukopenia, that makes the body more susceptible to infections.
Leukocytes can be divided into two large groups, the granulocytes and the agranulocytes.Granulocytes receive this name because, when subjected to certain dyes, they present granules that stain in a specific way, unlike agranulocytes. Granulocytes include neutrophils, eosinophils, and basophils, while agranulocytes include lymphocytes and monocytes.
You neutrophils are from the group of cells responsible for phagocytosis of strange particles. They stand out for being the most numerous cells among leukocytes. You eosinophils, in turn, they play an important role in parasitic infections and allergic processes. already the basophils they also act in allergic processes and release heparin in the blood, an anticoagulant substance.
You monocytes also perform phagocytosis, being called macrophages when they invade infected regions. You lymphocytes can be classified into B lymphocytes and T lymphocytes. B lymphocytes differentiate into plasma cells, cells responsible for producing antibodies. T lymphocytes, in turn, are divided into two classes: CD8 and CD4. CD8 T lymphocytes kill infected cells, and CD4 acts by activating other cells, such as the B lymphocyte. To learn more about these important cells of the immune system, read: Leukocytes.
Antibodies
As we saw in the previous topic, antibodies are produced by plasma cells, formed by the differentiation of B lymphocytes. These substances, also called immunoglobulins (Ig), are glycoproteins that interact specifically with the antigen (a molecule that can bind to the antibody) that stimulated its synthesis.
Antibodies, contrary to what many people think, are not responsible for the death of a disease-causing organism. In reality, they bind to antigens, triggering different processes.
One of them is the neutralization, in which the antibody binds to the antigen, preventing it from being able to destroy or infect cells. Another process that can occur is that of opsonization, in which the antibody binds to the antigen, promoting its recognition by macrophages or neutrophils that will carry out phagocytosis.
Also, the antibodies can trigger the add-on system, which promotes microorganism lysis. If you are more interested in this substance and its interactions with antigens, read: Antibodies.
lymphoid organs
Lymphoid organs are tissues that have a large number of lymphocytes in a region of non-lymphoid cells. Can be classified into central and peripheral. As central lymphoid organs, we have the bone marrow it's the thymus, lymphocyte producers. Bone marrow is where all blood cells are formed, including B and T lymphocytes. The thymus, in turn, is where the T lymphocytes complete their maturation. B lymphocytes differentiate in the bone marrow.
From the central lymphoid organs, lymphocytes are carried by the blood and lymph to peripheral lymphoid organs such as spleen, lymph node, isolated lymph nodes, tonsils and appendix. In them, T and B lymphocytes proliferate intensely, and this proliferation is usually stimulated by antigens.
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Innate and acquired immunity
Our body's ability to protect us from invading agents is called immunity. This can be classified in two ways: innate and acquired. THE innate immunity it is what the individual has had from birth. In it we have natural barriers acting, such as skin and mucous membranes, and also internal agents, such as leukocytes and phagocytic cells. In this type we have a unspecific answer.
THE acquired immunity it occurs throughout the individual's development and is more specialized. To be developed, it needs contact with an invading agent, which will trigger a series of events that lead to the activation of certain cells and the synthesis of antibodies. Acquired immunity can be classified into humoral or cell-mediated. The former is mediated by antibodies, and the latter by T lymphocytes.
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immunological memory
Immunological memory is responsible for the defense of our body in the long term. When we are exposed to a disease-causing agent, we trigger a response from our immune system. During this action, we have the formation of memory cells, which can survive for several years. When we are again exposed to the same threat, our immune system's response is even faster and stronger, due to the action of these memory cells.
Immunological memory is the reason why vaccines are so efficient. In vaccines, a disease-causing organism (dead, attenuated or even parts of this agent) is inoculated into a person, thereby stimulating their immune system. If that person has a new contact with this same agent, their immune system will respond quickly, preventing infection.
By Vanessa Sardinha dos Santos
Biology teacher