/əˈdren.əl.ɪn/
a substance produced in the body when you are excited, afraid or angry. It makes the heart beat faster and increases your energy and ability to move quickly. 肾上腺素（能使心跳加速、精力充沛、行动迅速）
The excitement at the start of a race can really get the adrenaline flowing.比赛起点的兴奋确实能使人热血沸腾。