The Immune System
The immune system is made up of two parts, innate and adaptive.
- The Skin (protects the body from pathogens).
- The mucous membranes (the thick mucus traps the pathogens and stops them from entering the body).
- Saliva (contains enzymes and antibodies that attack pathogens before they enter the body).
- Stomach acid (stomach acid and enzymes kill bacteria that enter the stomach).
- Tears and urine (flush out pathogens that are have entered the eyes or have travelled up the urethra).
- White blood cells (neutrophils, basophils and macrocytes are first to a site of infection and are non-specific).
- Phagocytes (swallow, kill and digest invading micro-organisms).
- Helper T cell (help mature B cells in to memory B cells and plasma B cells, they also help activate cytotoxic T cells and macrophages).
- Cytotoxic T cell (responsible for the lysis of virus infected cells and tumour cells).
- Memory T cell (provide the immune system with "memory" against previously encountered pathogens).
- Natural Killer T cell (able to recognise a wider variety of antigen classes once activated).
B cells (form and mature in the bone marrow. B cells are activated directly by coming in to contact with an antigen or a T cell which is presenting an antigen)
- Plasma B cells (proliferate and rapidly produce then release huge numbers of antibodies specific to the antigen presented to that B cell, the antibodies can then attach to the virus thereby entrapping it.
- Memory B cells are longer lived than plasma B cells and provide the body with a "memory" so that they are ready for any subsequent attack from the same pathogen exhibiting the same antigen.