Examples of Primary, Secondary and Tertiary Barriers

Every organism has a set of biological barriers that protect them from pathogens, that is, substances or other organisms that can cause disease. For example: skin, sweat, phagocytosis.

Its function is:

Biological barriers are part of the immune system. However, substances and tissues that function as barriers can also be part of other systems, such as the circulatory system or the integumentary system.

Examples of primary barriers

1. Skin. In humans and animals, is he organ larger. It isolates the organism from the environment that surrounds it but also allows a controlled exchange. When an injury occurs, this protection is disrupted. That is why wounds must be protected. It is a physical barrier.
2. Sweat. Create an atmosphere acid and salty on the skin which is unfavorable for a large number of harmful microorganisms. It is a chemical barrier.
3. Tears. They contain lysozyme, a enzyme that prevents the development of pathogenic microorganisms. It is a chemical barrier.
4. Mucous. Parts of the skin that surround organs that connect to the outside. They secrete mucus, preventing microorganisms from entering those organs.
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5. Bacterial flora. They prevent the presence of microbes in the mucous membranes.
6. Saliva. It also contains lysozyme.

Examples of secondary barriers

1. Phagocytosis. White blood cell reaction to infection.
2. Monocytes. They are found in the bloodstream and target injured tissues.
3. Macrophages. Engulf bacteria and harmful cells, as well as cellular debris.
4. Killer cells. They attack cells that have been invaded by virus.
5. Granulocytes. They react to infections.

Examples of tertiary barriers

1. T lymphocytes. Leukocytes that act directly on the pathogen. They cannot detect all antigens.
2. B lymphocytes. Leukocytes that create antibodies to each antigen. They develop in the fetus (liver and spleen) and in the adult bone marrow.

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