Immunity. Key Concepts
It has long been observed that people who suffered a dangerous contagious disease, the second time it is usually not ill. People have tried to use these observations in order to protect themselves from infection. China was invented method of dealing with severe cases of smallpox. He lay in the fact that smallpox scabs triturated and applied to the nose. This was done in order to cause a mild form of smallpox.
Immunity to reinfection of the same infection caused by immunity. The term “immunity” comes from the Latin word “immunis”. So in ancient Rome called citizen, free from some of the national service.
Currently under immunity understand:
resistance to infection
reactions lead to the disposal of the body of any foreign material.
What would have happened if there was no immunity?
There is a group of diseases related to the violation or no immunity, or any of its executives. This immunodeficiencies.
Immunodeficiencies may be congenital (a child is born to them, are often the cause of their development are defects in genes) and acquired (they are the result of effects on the environmental factors – infection, ionizing radiation, etc.).
A bit of terminology:
Antibodies or immunoglobulins – are molecules of protein nature. They are synthesized in the body (normal), after it is administered antigen. The antibodies bind to the antigen and neutralize it.
Antigens – large molecules (macromolecules), which can stimulate the synthesis of antibodies, and to contact them. Antigens can be located on the cell surface (microbial antigens) or to be free (toxins).
Cells of the immune system. Cells, somehow involved in the immune response, very much, the main ones – macrophages, white blood cells: lymphocytes (T-cells and B-cells) and granulocytes (neutrophils, eosinophils, and basophils).
Of the immune system.
There is a kind of hierarchy of the immune system. One can distinguish the primary – the most important (bone marrow and thymus or thymus) and secondary (lymph nodes, spleen, lymphoid tissue associated with mucous membranes) bodies.
They are all connected to each other and other tissues of the body through the blood and lymph vessels, which move leukocytes.
In it from the stem progenitor (ancestor of all blood cells) appear immune system cells.
There are also differentiation [from Lat. differentia - the difference, the appearance of the cells as a result of development of morphological (structural) and functional differences] B cells (in birds, this process occurs in the bursa of Fabricius).
There is evidence indicating that the bone marrow is a major site of synthesis of antibodies. Thus, in the adult mouse bone marrow is up to 80% of cells synthesizing immunoglobulins. Intravenous administration of bone marrow cells can restore the immune system in fatally irradiated animals.
In the thymus is maturing progenitor cells of T-lymphocytes and their transformation into a mature form.
T cells, showing hostility to the body’s own antigens, undergo apoptosis (programmed cell death).
The thymus also produces a number of hormones (eg, thymosin) that regulate the differentiation and function of T lymphocytes.
This peripheral organs of the immune system, located along the lymphatic vessels. The main function – the arrest and prevent the spread of antigens at the expense of T-and B-lymphocytes (T-and B-dependent areas).
Spleen delays and destroys antigens that circulate in the blood.
In addition, there are produced immunoglobulins. After splenectomy decrease the level of antibodies in blood serum.
Spleen – a place of education hormone-like substances – cytokines (taftsin and splenin) involved in the regulation of macrophages.
In the spleen is damaged and phagocytosis of old red blood cells.
Associated lymphoid tissue of the mucous membranes
To refer to it in English literature abbreviated MALT. This type of lymphoid tissue located under the epithelium. It includes an appendix, lymph follicles and intestinal lymphoid ring Pirogov (lingual palatal + + pharyngeal tonsils). MALT – is a barrier to the penetration of microorganisms through the mucous membranes.