system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 - Why is it when a person puts their finger so back in their mouth they gag but when eating it triggers no gag reflex?

Do food move down your throat differently than just going down?
gpt
When people are putting their fingers into the back on their mouth they are poking their uvula - its that thing that you can see hanging down in the back of your throat.  Anything that puts enough pressure on that will cause you to gag/puke.

When you swallow, the uvula gets pulled up so that its flush with the roof of your mouth.  This prevents the uvula from being stimulated.  You can feel this occurring - if you just swallow some saliva concentrate on the rear part of your mouth.  You'll feel it kind of pull up and away from your throat - that's your uvula getting out of the way of anything that is coming down which prevents the gag reflex from activating while you're swallowing food.