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The immune system defends the body against worms, bacteria, and other harmful substances. The immune system resembles a castle from the Middle Ages. A moat and lofty stone walls surrounded the fortress on all sides. Soldiers stood poised within the castle to fight off any invaders who managed to get past the outside fortifications. The immune system, like a medieval fortress, has a set of fortifications. It has three lines of defense in fact. Only infections that manage to get past all three levels of protection are capable of causing harm to the host.
Most infections are kept out of the body by the body’s first line of defense, which consists of many sorts of barriers. Pathogens, such as bacteria and viruses, are disease-causing agents. These and other pathogens are depicted in the diagram below. The initial line of defense, however, is always the same, regardless of the disease.
Bacteria, viruses, fungus, and protozoa are examples of pathogens that typically cause human disease.
Mechanical Barriers
Pathogens are physically prevented from entering the body via mechanical barriers. The most important mechanical barrier is the skin. It is, in reality, the body’s single most critical defense. The skin’s outer layer is strong and infections have a hard time penetrating it.
At body openings, mucous membranes act as a mechanical barrier. The pulmonary, gastrointestinal, urinary, and reproductive processes are likewise lined with them. Mucus is a slimy material secreted by mucous membranes that traps germs. Cilia, which look like hairs, are also present on the membranes. Mucus and infections are swept by the cilia toward body openings, where they can be eliminated. Pathogens are eliminated from the nose and throat when you sneeze or cough .Pathogens are washed out of the eyes by tears, and pathogens are flushed out of the urinary tract by urine.
Many pathogens can be expelled from the respiratory tract by sneezing. As a result, you should always cover your mouth and nose when coughing or sneezing.
Chemicals Barrier
Chemical barriers kill infections on the outside of the body, at body openings, and in the linings of the body. Sweat, mucus, tears, and saliva all contain pathogen-killing enzymes. Many pathogens cannot tolerate the acidity of urine, and semen contains zinc, which most bacteria cannot tolerate. In addition, germs that enter the GI system by food or drink are killed by stomach acid.
Biological Barrier
Biological barriers are live entities that aid in the body’s protection. The human skin is home to millions of germs that are completely harmless. Many more are found in the gastrointestinal tract. Harmful bacteria cannot flourish because the harmless bacteria consume food and space.
Physical Barrier
Physical barriers are critical in preventing germs from infiltrating infection-prone tissues. Barriers are formed up of tightly bonded cells that prevent invaders from reaching deeper tissue. Endothelial cells, which lining blood arteries, have extraordinarily tight cell-to-cell connections that keep infections out of the circulation. Cell junctions are formed by cell membrane proteins that connect to the extracellular matrix or by complementary proteins from neighboring cells. Cell junctions of various sorts can be found in a variety of tissues throughout the body. Tight junctions, desmosomes, and gap junctions are only a few examples.
Conclusion
We conclude that the body’s first line of defense is barriers that keep viruses out.
Mechanical, chemical, and biological barriers form the initial line of protectionThe immune system activates specialised and nonspecific immune responses in response to invading infections and cancer cells. Immunotherapy aims to boost these responses in order to stop cancer cells from spreading. The impact of stress on immunological and cytokine responses is still being researched.
