system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do inhalers let you breathe instantly during an asthmatic attack?
gpt
An asthma attack happens when parts of the lungs squeeze shut, generally in response to a perceived threat. This stops air from reaching the lungs. Normally,  your brain sends a signal to these parts of the lungs telling them to open again shortly afterwards, but for one reason or another this doesn't happen for someone experiencing an asthma attack.

The drug in a rescue inhaler (called a bronchodilator) simulates the kind of signal your brain would normally send, causing the airways to open on contact, letting air back into the lungs.