Re: Why does heart rate increase when a person is scared?

The body is equipped with a very nice emergency system which when activated is called the sympathetic response.  This system, which is part of the autonomic nervous system (subconscious level of operation), will prepare the body for fighting or fleeing in emergencies.  Part of that response is to get your heart pumping faster and more efficiently.  It also involves many other things like increased respiration, decreased activity of the gastrointestinal tract, increased transmission of action potentials across nerve synapses, increase the livers release of glucose into the blood stream, and so on.  All of these things allow you to fight or run at your best, so when you get scared your body reacts to help you be ready to run and so part of that is the increased heart rate.  You might also notice that your hands get a bit "clammy" and you get "goose bumps" on your skin.  This is also part of the sympathetic response and you should read up on why this occurs in encyclopedia in your library.