system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:When I get "butterflies in my stomach", what is actually happening inside my body?
gpt
When your body goes into fight-or-flight stress response, it is preparing to fight a physical threat or run away from it. To help you do this, your heart rate and breathing speed up, you sweat, and blood flow is diverted from non-essential systems to the major muscle groups. Digestion is a non-essential system, so when stress hormones are in your blood, your digestion slows way down. The weird feeling in your stomach is the reduction of blood flow to your digestive organs, so that the blood can go to your arms and legs instead.