Active immunity occurs when our body is exposed to pathogens. Protein known as antigen could be found of the surface membrane of the pathogen. These antigen are unique for each different pathogen. This antigen will bind to a receptor of a B cells which is complementary to it and trigger our body's immune response. Selected B cells is activated and divides by mitosis. Some of it is developed into plasma cells and others into memory cells. Plasma cells secretes antibody to act on the pathogen. Memory cells is left in our body for a long time. If the same pathogen invade our body again, the immune response will be stronger due to the presence of memory cell leftover from the previous immune response.Active immunity is usually long lasting.
There are two types of active immunity:
- Natural immunity - usually occurs when our body is encouter disease carrying pathogen. The pathogen infects our body and this triggers immune response.
- Artificial immunity - Weakened or inactivated pathogen is injected into our body to trigger our body's immune response. This is also know as vaccine-induced immunity
- ↑ http://microbiologyonline.org/about-microbiology/microbes-and-the-human-body/antibody-antigen-complex
- ↑ https://www.cdc.gov/vaccines/vac-gen/immunity-types.htm