Immunity. The immune system is a group of cells and organs that defend the body against invaders causing disease

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Immunity

The immune system is a group of cells and organs that defend the body against invaders causing disease. The immune system is made up of mostly white blood cells and their contact with lymph nodes, spleen, tonsils, intestines, and lungs. The immune system rejects and attacks any substances not normally present within the human’s body. Innate, or nonspecific, immunity is functioned by the skin, tears, mucus, and saliva. These barriers protect the body from a disease’s entrance, but do not prevent it. Adaptive, or specific, immunity processes when invaders actually attack the body. In adaptive immunity, proteins called antibodies appear in body fluids to fight bacteria and toxins, while other cells in adaptive immunity resist a virus’ reproduction within cells. Resistance called immunity is reached by active or passive immunization. Active immunization occurs when a person’s immune system becomes activated and generates a response or by a vaccination. Natural immunization is controlled by a person’s immune system, while a vaccination is a chemically-created weakened form of the disease unable to cause harm. Passive immunization is when a person receives only temporary immunization by the use of antibodies.

There are 2 types of defence mechanisms, Non Specific and Specific. Non specific mechanisms don’t distinguish between one type of pathogen and another, but respond to all of them in the same way. They act immediately and take two forms, a physical barrier to the entry of pathogens and phagocytosis. The second defence mechanisms are specific mechanisms that distinguish between different pathogens; the responses are less rapid but provide long lasting immunity. The response involves a type of white blood cell called a lymphocyte which takes two forms, T lymphocyte (cell mediated response) and B lymphocytes (humoral response).

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As mentioned before phagocytosis is used to destroy pathogens, this is done by a white blood cell called a phagocyte that ingests and destroys the pathogen. Phagocytosis is the process that engulfs bacteria in cells in the form of vesicles formed from the cell surface membrane. Phagocytes provide an important an important defence against pathogens that manage to enter the body, some phagocytes travel in the blood but can move out of blood vessels into other tissues. During phagocytosis adherence or attachment is the first phase, when the firm contact between the cell membrane of the phagocyte and the microbe ...

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