Stress Reactions Stress is part of life. This physical reaction is related to powerful feelings such as fear, anger and frustration.
Adrenaline causes the heart to beat faster and increases respiration rate.
Another hormone is released that causes the liver to release sugar for extra energy. The mouth becomes dry, pupils of the eyes dilate, and the lungs take in more air. Blood moves from the stomach into the skeletal muscles. Hearing becomes more acute and muscles contract. This fight or flight response provides animals and people the extra energy and strength they may need to protect themselves in times of crisis.