Fight or flight

• What are some physiological changes in the 'fight or flight' response?

  • increased HR
  • pupils dilate/tunnel vision
  • sweat
  • digestion decreases/salivation inhibited/immune system suppressed
  • going pale
  • increased pain tolerance
• How does increasing HR/blood pressure help during 'fight or flight' response?


  gets more blood (containing nutrients/oxygen) to the muscles that allow you to fight or flee
• How does dilating pupils help during 'fight or flight' response?


  allows more light to enter the eye so you can see really well -> vision focused on threat
• How does sweat help during 'fight or flight' response?


  cooling mechanism to counteract heat produced from fighting/running
• How does suppressed digestion/immune system help during 'fight or flight' response?


  digestion isn't needed during fighting/running so energy can be saved by reducing these
• How does going pale help during 'fight or flight' response?

  blood directed away from the skin reduces risk of blood loss increase of injury while increasing blood flow to muscles
• How does increased pain tolerance help during 'fight or flight' response?

  natural painkillers (endorphins) released so you can keep fighting/fleeing even if hurt
• What happens to the body once the threat has passed?

  we switch from sympathetic to parasympathetic state which involves all the physiological changes reversing
• What happens when a threat is sensed?

  information is sent to the amygdala
• What is the role of the amygdala?

  area of the brain that processes emotions (e.g. fear)
• What happens after info is sent to the amygdala?

  either the SAM axis (pathway 1) is triggered or the HPA axis (pathway 2) is triggered
• What does SAM axis stand for?

  sympathomedullary axis
• What does HPA axis stand for?

  hypothalamic pituitary adrenal axis
• When is the SAM axis triggered?

  seconds after a threat has been noticed
• When is the HPA axis triggered?

  20-30 minutes after a threat has been noticed + response is still necessary
• What happens in the fight or flight pathway 1 (SAM axis)?

  signal is sent to hypothalamus --> signal sent to adrenal medulla --> adrenaline is released
• What happens in the fight or flight pathway 2 (HPA axis)?

  signal is sent to hypothalamus --> corticotropin releasing hormone (CTH) is released --> CTH signals pituitary gland to release adrenocorticotropic hormone (ACTH) --> ACTH signals adrenal cortex to release cortisol
• What are the effects of the 1st fight or flight pathway?

  • HR/blood pressure increases
  • heightened senses
  • sweat
  • going pale
• What are the effects of the 2nd fight or flight pathway?

  • increase adrenaline sensitivity
  • increase glucose production
  • break down fat for energy
  • enhance memory systems
  • increase temporary immunity
  • decrease long term immunity