Does your heart rate change when you are happy sad or scared?

Your muscles require oxygen/nutrients to move you, as you exercise/move your muscles need more and more, so your oxygen demand gets higher so you breathe more heavily and your heart beats faster to provide your body/muscles the oxygen it needs. Your heart is controlled by the smpathetic nerves and the parasmpatheitc nervs- two sets of chemicals called neropinephrine and epineprhine heart rate changes normally depending on many things including 1) some foods 2) your breathing rate For more information contact me http://wiki.answers.com/Q/How_heart_works&alreadyAsked=1