Antigen

Real World Example

Imagine you're at home, and an unexpected guest rings your doorbell, causing your dog to start barking loudly. Just like this surprise visitor disrupts the peace in your home and prompts a reaction from your dog, an antigen is a foreign substance entering your body, triggering a response from your immune system. In this analogy, the unexpected guest is like the antigen, your dog's barking is akin to the immune system's response, and just as you may try to calm your dog or deal with the visitor, your immune system works to address the foreign intrusion.