The human immune system is more like a defence mechanism of the body which is essential for our survival and helps us fight many diseases and infections. The immune system is made up many special cells, tissues, organs, proteins etc. Interferons and Lymphoid Organs are part of the Immune System of the human body.
Interferons help in protecting us against microorganisms and germs that cause diseases thereby keeping us healthy. With the help of the immune response, the immune system attacks the organisms that invade the body. But, when the immune system of the body fails for some reason, then the body is prone to infections.
The ability of the body to fight the disease-causing organisms due to the working of the immune system is called as Immunity. It has great importance in medicine because it probes into the various causes of diseases due to lack of immunity.
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- Health and Diseases
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- Immune System
- Antigen and Antibody
- Disorders of Immune System
- Vaccines and Immunisation
- Drugs and Alcohol Abuse
Types of Immunity
Immunity can be classified into two types. They are the Innate immunity and Acquired Immunity.
This type of immunity is present at the time of birth. Everyone is born with a level of immunity. This is generally the first line of defence against foreign bodies or invaders. This immune response is non-specific and general in nature. It involves many effector mechanisms. The cells that mediate the innate immunity are the granulocytes and leucocytes.
Depending on the types of barriers, innate immunity is of four types. They are:
- Physical barriers – They prevent the entry of microorganisms. Skin is the main barrier that prevents the entry of foreign microbes. The mucus coating of the epithelium that lines the gastrointestinal tract, respiratory tract, urogenital tract also trap any microbes that try to enter the body.
- Physiological barriers – These barriers prevent the microbial growth in the body. the acid in the stomach or even the saliva in the mouth and tears from eyes prevent this microbial growth.
- Cellular barriers – If microbes do enter the body, these cellular barriers protect by killing and destroying the microbes. Some leukocytes like the polymorpho-nuclear leukocytes (PMNL-neutrophils) and monocytes and natural killer, a type of lymphocytes in the blood along with macrophages in tissues are all examples of cellular barriers.
- Cytokine barriers – These barriers are virus-infected cells that secrete proteins called interferons. They protect the other non-infected cells from any further viral infection.
This is a type of immunity that develops during an individual’s lifetime and is present from birth. This immunity is characterized by memory and is always pathogen-specific. Acquired Immunity can be of two types – antibody-mediated immunity and cell-mediated immunity.
The lymphoid organs in the human body include the spleen, lymph nodes, bone marrow, thymus and lymph tissue.
- Lymph nodes- These are small, bean-shaped structures which produce and store cells, specialized in fighting infections. They are a part of the lymphatic system. Lymph nodes have lymph. When the body is in the process of fighting an infection, they are enlarged and sore.
- Spleen– It is the largest lymphatic organ in the body. It has white blood cells that fight infections. The spleen is an organ that also disposes of old, damaged blood cells.
- Bone marrow – The center of some bones like the hip bone, thigh bone has a yellow tissue that produces white blood cells. The spongy tissue inside these bones has the stem cells. It is the main lymphoid organ which produces the blood cells, including the lymphocytes. In the bone marrow, the immature lymphocytes differentiate into antigen sensitive lymphocytes.
- Thymus- This is the organ where the T-cells mature.
- Lymphoid Tissue – the lining of major tracts such as the respiratory, digestive and urogenital tracts have lymphoid tissue called the mucosa-associated lymphoid tissue (MALT).
Solved Questions For You
What are the primary and secondary lymphoid organs?
Ans. The primary lymphoid organs are thymus and bone marrow. The secondary lymphoid organs are the lymph nodes, spleen, and the lymphoid tissue, MALT.