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Immune system is a complex network of cells, tissues and organs that protects our body against various diseases and infections. The immune system defends our body from harmful or foreign substances known as antigens. These antigens can be bacteria, viruses, chemicals, toxins etc.
When the immune system recognises an antigen, it attacks the antigen which is referred to as immune response. This creates antibodies which work against these antigens by attacking, weakening or destroying. Afterwards, the immune system remembers these antigens, and if they appear again they quickly recognise these antigen and send the right antibodies. This process of protection against a certain disease is called immunity.
Autoimmunity refers to immune responses in an organism in which the immune system reacts against its own healthy tissues, cells and other constituents. Allergies are reactions that occur when the immune system in an organism reacts to foreign materials in the environment.
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Keyterms: Immune system, Immunity, Bacteria, Viruses, Chemicals, Toxins, Antibodies, Antigen, Disease, Allergy, Cell, Autoimmune disease
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What is Autoimmunity?
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Autoimmunity is a system when an immune system attacks against its own healthy tissues and cells mistakingly. Hence, any disease that occurs due to abnormal immune responses is termed as 'autoimmune disease'.
There are many autoimmune disorders such as Graves disease, type 1 diabetes mellitus, rheumatoid arthritis, Hashimoto thyroiditis etc. Diseases namely Addison disease, progressive systemic sclerosis, polymyositis etc are also considered as autoimmune disorders.
What is Allergy?
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An allergy is the immune response to a foreign substance which isn't typically very harmful to the human body. These foreign substances are known as allergens and include certain foods, pollens, insects, animals etc. Substances that can often cause allergic reactions are as follows:
- Pollen
- Certain medicines
- Dust
- Certain Food
- Insect
- Animals
Allergies are caused due to release of certain chemicals such as serotonin and histamine. In reaction to the allergens, a human body produces antibodies called (IgE) immunoglobulin E antibodies.
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Causes of Autoimmune Disorders
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Autoimmune reactions can be triggered in the following ways:
When in a normal body, a foreign substance appears and alters a part of the body such as entering of virus which affect and alter the cells in the body, the virus infected cells stimulate immune response leading to attack.
Sometimes a foreign invader might resemble a natural body substance. The immune system may attack the foreign substance as well as the similar body substance. For example, bacteria which causes strep throat have antigens similar to antigens present in human heart cells.
The cells that control the production of antibodies can malfunction and produce abnormal antibodies which can further attack the body's healthy cells.
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Difference and Similarities between Autoimmune and Allergy
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Similarities:
- Both can result in general feeling of sickness and fatigue
- Both autoimmune disease and allergy have itching as common symptom
- Due to proactive immune system in both the cases, redness and swelling is common in the affected area.
Differences:
- Allergy is a reaction when the immune system reacts abnormally to the foreign substances whereas, in autoimmune disease, the immune system attacks healthy tissues and cells of the body.
- Allergies are mainly triggered by external elements such as certain foods, medicines, insects etc whereas autoimmune reactions occur due to internal triggering to the body's cells.
- Examples of both of them vary. Allergies can be in various forms such as skin allergy, asthma, sinuses etc. Examples of autoimmune diseases are multiple sclerosis, inflammatory bowel disease, type 1 diabetes etc.
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Things to Remember
- An autoimmune disease occurs due to malfunction of the immune system.
- An autoimmune disease causes the immunity system of the body to attack its own healthy cells and tissues.
- symptoms of this disorder vary according to the affected area and several blood tests are useful to detect the autoimmune disease.
- If a natural body substance resembles a foreign object, then the immune system may attack the foreign substance.
Also Read: Human Health
Sample Questions
Ques. What are autoantigens? (2 marks)
Ans. Autoantigens also known as self antigens typically consist of proteins, complex enzymes, DNA or several other components against which antibodies are directed. It induces formation of antibodies in another organism, however, the immune system of the parent organism is tolerant.
Ques. What are autoimmune diseases? (2 marks)
Ans. Normally our immune system guards are body against foreign invaders such as virus or bacteria by sending out an army of fighting cells to attack them. Immune system can recognise these foreign invaders and its own cells. However, in autoimmune disorders, the immune system mistakenly recognizes a part of the body such as joints or skin as foreign and releases autoantibodies to attack them.
Ques. What are the examples of autoimmune diseases and its affected area? (2 marks)
Ans. There are several autoimmune diseases such as Type 1 diabetes which affects insulin-producing cells in the pancreas, Rheumatoid arthritis (RA) which attacks joints, Multiple sclerosis which is associated with brain and spinal cord, Systemic lupus erythematosus (SLE) causing skin disease, Inflammatory bowel disease leading to inflammation in intestinal walls, Graves’ disease related to thyroid gland etc.
Ques. Who can develop autoimmune diseases? (2 marks)
Ans. Due to some genetic condition or other unknown reasons, a person can develop autoimmune disorders in their body. For example certain autoimmune diseases such as multiple sclerosis and lupus run in families. Higher exposure to some chemicals or toxins can also result in rising cases of autoimmune diseases.
Ques. What are the symptoms of allergy? Give examples. (2 marks)
Ans. Allergy can cause a variety of symptoms to the human body such as itching, runny nose, watery eyes, rashes, swelling, or asthma. The symptoms can differ from severe to mild. Anaphylaxis is a severe allergy that could be life threatening. Several blood tests and skin tests can diagnose the allergy.
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