system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: the physiology of that "butterflies in your stomach" feeling.

I'm studying a bit of human biology at university, so you can explain like I'm six for this one!

Edit: I'm also wondering if it differs between situations, such as when you feel nervous or in danger, when you go down a big water slide, when you kiss someone special, that sort of thing?
gpt
From what I've heard before, that feeling comes from our Fight or Flight instinct. Your body senses that you're nervous (that's fear) for something coming up, and as a natural response from the fear, your body begins preparing itself for the potential of fighting/flight. It sends more blood to the more important areas of your body (eg muscles in your arms, abs, and legs) so that if you have to fight/flee, you can in a better way. The butterfly feeling is what happens when blood is rushed away from your stomach area, simply put.