After my trip to playland I realized just how much stress amusment park rides can place on one's heart.  Waiting in line for the ride did not greatly increase my heart rate because I was not placing my body under stress. However, when I got closer to the to getting into the ride, my heart rate increased in anticipation and stress from the build up of fear. On the ride my heart rate was the most spiked, especially on the first drop on the wooden rollar coaster and rught before it. My heart rate is affected because fear and stress cause adrenaline to start entering the blood stream and cause the heart to work  harder in response to a fight or flight situation.  Adrenaline works the body and causes more energy to be used in the muscles and thus the body is craving for more energy and needs more oxygen to support this need. This is why breathing rate increases. I did not experience many other things other than butterflies in my stomach and this is attributed to the body's fight or flight response.