Imagine having an army of soldiers, always on the lookout and ready to jump into action anytime an enemy crosses your borders. In this case, the enemies are in fact bacteria, viruses and other pathogens (any organism which causes disease), the borders represent your body and the soldiers are actually specialized cells, tissues and organs that work together to protect you against harmful invaders.
The immune system
Is a complex network of cells, organs, tissues, and proteins with the main role of protecting you from pathogens, or in extreme cases, minimalizing the damages. It can differentiate healthy tissue from foreign organisms. If unwanted substances are detected, the immune response begins- a series of attacks happen in order to protect the body from invaders. It also recognizes and removes dead and faulty cells. The immune system consists of: leukocytes (white blood cells), the spleen, bone marrow, the lymphatic system, the thymus, the tonsils, adenoids, and appendix.
The immune system can be divided into two parts: innate immunity and adaptive immunity.
The innate immunity includes the external barriers (skin, mucous membranes) and is the first line of defence an intruder encounters, it’s a non-specific mechanism used immediately or within hours of the infection. Early in the immune response, phagocytes, neutrophils and macrophages more exactly, are the first to provide a response to inflammation. They engulf and digest the invaders, a process called phagocytosis. The pathogens which are not destroyed by them “attract the attention of lymphocytes”.
The adaptive immunity is more specialized. Although it takes longer to respond, it targets specific pathogens. In this part, lymphocytes are activated and antibodies are produced. Both types of lymphocytes, T-cells may destroy infected cells directly, while B-cells produce antibodies. They bind to antigens (foreign substances), neutralizing it and making it easier for phagocytes to ingest and destroy. After killing the intruders, some T and B-cells become memory cells, “remembering” the specific pathogen, allowing for a faster and more efficient response if the invader were to attack again in the future.
Vaccination has similar principles, being an important mean of helping our immune system. They work by introducing a harmless part of a pathogen (an inactive virus or a protein) to the body, encouraging the immune system to create memory cells.
Although the immune system is essential in our survival, it can sometimes malfunction and lead to conditions such as allergies and autoimmune diseases. Allergies occur when the immune system overreacts to harmless substances known as allergens, like pollen, animal saliva, or certain foods. During the first exposure to an allergen, the immune system mistakenly identifies it as harmful. Then B-cells are activated and produce antibodies specific to the allergen. The antibodies then bind to some types of white blood cells. Upon re-exposure, the same allergen binds to these antibodies, triggering the white blood cells to release inflammatory chemicals, which lead to the well-known symptoms: sneezing, itching, swelling and in extreme cases to anaphylaxis, which is life-threatening.
Autoimmune diseases appear when the immune system mistakenly attacks the body’s own tissues, seeing them as invaders. Usually, the immune system differentiates self from non-self, but that is not the case with autoimmune diseases. Autoantibodies and autoreactive T-cells attack specific tissues, which leads to chronic inflammation and damage to tissues and organs.
The immune system is vital for protecting the body, but its errors can lead to conditions like allergies and autoimmune diseases. Understanding the mechanisms behind the immune system response can help in understanding the causes of these conditions and finding ways to improve the quality of life for those affected.
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