adrenaline , stressed, angry, excited, or frightened your body eneds to be ready for action. adrenaline causes, your heart rate and breathing to increase, stored glycogen in the liver to be converted to glucose for respiration, the pupils of your eyes to dilate to let in more light, your mental awareness to increase.
adrenaline boosts the delivery of oxygen and glucose to your brain and muscles, preparing your body for fight or flight.