Fight-or-flight response

• What are the steps for the flight-or-fight response?

  Stressful event occurs.

  1. Stressor is perceived
  2. Hypothalamus triggers activity in the sympathetic branch of ANS
  3. ANS goes from resting state (parasympathetic state) to physiologically aroused (sympathetic state)
  4. Adrenaline is released from adrenal gland - adrenal medulla
  5. Adrenaline triggers physiological changes
• Name the physiological changes in the sympathetic state


  • increased heart rate
  • increased breathing rate
  • dilated pupils
  • inhibits digestion
  • inhibits saliva production
• Name the physiological changes in the parasympathetic state


  • decreased heart rate
  • decreased breathing rate
  • constricted pupils
  • stimulates digestion
  • stimulates saliva production