When someone sneaks up behind you and shouts “Boo!” For a little bit your heart beats faster, even though you didn’t do any physical activity that would of course increase your heart beat. But what caused your heart to behave this way after being startled or surprised?
When I am startled my body becomes aware of a potential threat, or something that may potentially be dangerous for me. When my body is aware of this it releases certain chemicals and hormones which will put my body into the mode of “fight or flight.” The unique phenomena of “fight or flight,” heightens my senses, and is my body’s response on how to react to potential danger, by either “fighting,” or “running.”
In short, this is why your heart beats quickly when you are surprised/startled.