Ciara is driving home from school, listening to her favorite music, when a dog darts into the street in front of her car. She manages to swerve to avoid hitting the dog. As she continues on her way she notices her heart is racing, she has "goose-bumps" and her hands are sweaty.
When the dog darted in front of Clara's car, her body went through a sympathetic "fight-or-flight" response, which is an inborn, automatic effect that can occur under conditions of acute stress.(1&2) The effects may have also included pupils dilating, airways to her lungs dilating, blood vessels to her kidneys and gastrointestinal tract constricting, blood vessels involved in exercise to fight off danger dilating, release of glucose by the liver, liver cells performing glycogenolysis.(1p537)
The effect is triggered by acetylcholine released from sympathetic nerves, which can activate many tissues simultaneously.(1p537 & 2) A release of adrenaline and norepinephrin from the medulla of the adrenals facilitate the intense physical effects.(2) We share this response with many other animals.(2)
Gives you a new reason to make sure you get the choline you need daily for synthesis of acetylcholine.
1. Tortora, GJ & Derrickson, B. Principles of Anatomy and Physiology, 11th ed; 2006. New York: John Wiley & Sons.
2. Psychologist World. Stress: The fight or flight response. Available at: http://www.psychologistworld.com/stress/ fightflight.php. Accessed on Oct. 25, 2008.