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Organs of the immune system

immune system

The immune system is the body’s fighting mechanism. The immune system of the body helps fight against infection caused by any foreign body entering/ invading the host i.e. our body. There are various mechanisms to fighting these organisms these are regulated based on their different locations in the body. It has now more than ever become more important to understand the full function and regulation of the immune system and to try and enhance its activity. The white blood cells, the antibodies, the thymus, the spleen, the lymphatic system and the complementary system are the main parts of the body’s defense/ immune system. These work coherently on different types of infections to prevent extreme damage to the body.

Infections in a person’s body may be a cause of a number of factors some may be due to parasites eg. Malaria, some others may be of a bacterial origin eg. Leprosy or tuberculosis. where as some others may even be a source of viruses eg. Influenza or the common cold similarly, human body can be infected by invasion of any similar type of foreign bodies. It is important to understand how these organisms enter the body and how our body reciprocates so that minimal damage is caused.

You might also be interested in Yoga poses to boost immunity.


Non specific defenses

Non-specific defence is the in- born or the innate immunity. These are the receptors or defences that a person is born with and usually consist of both physical as well as chemical barriers; that is, membranes to physically protect the body and phagocytes to help fight infections once they enter the body. They commonly produce only generalized type of responses.

First line of defense in the body:

The first line of defence refers to the physical barriers of the body. They include the largest organ covering the body that is the skin and other mucous membranes. The skin, having very low permeability, protects from any foreign object entering our body. A tear in the skin may however compromise his defence mechanism. The mucous membranes are another set of first line defences. The mucous members covering the respiratory or the gastrointestinal tracts, trap the foreign organisms on entry thus protecting the body.

Secretions on the surface of the body which include lachrymal secretions, sweat, etc. Are also a part of first line defences as they have a highly unusual pH that cannot be tolerated by most organisms.

Second line of defense in the body

The second line of defences comprise of the chemical barriers in the body. These are activated in cases where physical barriers fail to provide necessary protection. Phagocytes, antimicrobial proteins, inflammation and fever are included in the second line of defences. Example in case if skin tears, organisms can easily enter the body thus disrupting the normal functioning of the body; in such cases, the as the organisms or bacteria enter, they are trapped and killed by phagocytic lymphocytes in the body.

Fever and inflammation are usually responses to activation of the secondary barriers.

Specific defenses

These are adaptive defence mechanisms. Lymphocytes, antibodies and memory cells are a part of this defence mechanism. These are triggered by molecules in the body/ blood thus resealed to act specifically on a certain type of organism. Hence these react in specific manner to specific organisms.


Primary defense organs

The primary organs of the immune system are the ones where in, the cells to fight off diseases are produced and matured. The bone marrow and thymus are the primary organs of the immune system. The bone marrow produces cells and the lymphocytes that then move on to other parts in the body to provide immune responses. The thymus on the other hand, located just above the heart is responsible for the production of T- cells that assist the lymphocytes in their function. The T- cells are also differentiated into memory cells that remember the encounter with a past infection and can reciprocate appropriately in case of reinfection.

Secondary defense organs

Once cells are produced in the bone marrow and differentiated into in the thymus, they are transported to other secondary organs through blood wherein they carry out their actual job of fighting pathogens in that specific area. Lymph nodes, spleen, tonsils and some tissues with mucous membrane covering fall under the secondary lymphoid organs.

The spleen which is close to the abdomen a site where these defence cells are stored. The phagocytes i.e. the scavenger cells act as a filter for toxins in the blood. They also breakdown the platelets in the blood stream helping with the blood clotting factors. Tonsils present in the throat are a store house of white blood cells and helps fight infections actively. Tonsils are also in a constant battle with various micro organisms that enter through the mouth and the nose.

Mucous membranes in the interior of the body that is the ones lining the urinary tracts, the gastrointestinal tracts are extremely important in supporting and regulating the normal flora in the body while ensuring no other foreign bodies remain suspended in the body.

The human gut

It is very often said that the gut is responsible for immunity. Many scientists believe that around 70% of the immunity comes from the gut. The reason behind this is that most of the body’s normal flora resides in the gastrointestinal tract. These organisms help in maintaining the body’s temperature, pH, etc. thus contributing in a healthy immune function.

Thus the human body works constantly in a number of different ways to produce immune response and thus protect itself from any foreign organism that enters/ tries to invade. The organs of the immune play different roles in body’s regular and healthy functioning.

Organs of the immune system



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