| Q: Why does the immune system react faster to a pathogen if it's been exposed to that pathogen before? A: When the immune system is exposed to the pathogen for the first time, there aren't many cells which are already specifically ready to fight it. Though it takes some time to replicate enough of the appropriate T & B-cells to fight the pathogen, some of the T and B cells which are produced during the initial infection stay around in the body just in case the pathogen comes again. Some of these cells that stay are cells called memory T & B-cells. These special memory cells are specially equipped to quickly respond to the pathogen if it infects the body again. Push play to hear the answer. |
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