Mystery #4Tier 2nervous system / heart
Why does your heart pound when you are scared or excited?
A door slams behind you, or you step up to do something exciting, and in less than a second, before you've even finished the thought, your heart is hammering, your breathing quickens and your whole body feels switched on. You didn't decide to do any of that. So what flips the switch so fast, and why your heart of all things?
Your guess
What's your hunch about what makes your heart suddenly pound when you're scared or excited?
There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.
Make a guess to unlock the hints and the answer.