fight or flight

• FIGHT OR FLIGHT

  • The brain detects threat.

  The first thing that happens is a part of the brain called the hypothalamus identifies the threatening event (sometimes called the stressor) and instructs the sympathetic division of the ANS to act. - The release of adrenaline

  The ANS changes from its normal resting state (the parasympathetic state) to a state of physiological arousal (the sympathetic state). The stress hormone adrenaline is released from the adrenal glands (just above the kidneys) into the bloodstream.
• Once the threat has passed

  When the threat has passed, the parasympathetic division returns the body to a resting state. the parasympathetic division works in opposition to the sympathetic division. This means it reduces the activities of the body that were increased during fight or flight.

  During physiological arousal digestion is prevented so the body's resources are available for fight or flight. When the threat (stressor) has stopped, a person may feel hungry or thirsty having used up so much energy during fight or flight - and because digestion is now stimulated.
• The 'fight or flight response' describes all the physiological changes that occur due to the release of adrenaline.

  Adrenaline has an especially strong effect on the cardiovascular system and explains why, when you are scared your heart starts to thump immediately.

  The physiological changes associated with the sympathetic state are an increased heart, increased breathing rate + dilated pupils

  All of these changes occur immediately after a threat is perceived. AUTOMATIC RESPONSE

  These changes are designed to help us confront the threat 'fight' or give us the energy to run away 'flight'.
• The fight or flight response refers to the way we respond when stressed.

  • A person enters a stressful or dangerous situation
  • The amygdala (part of the limbic system) is activated which sends a signal to the hypothalamus
  • The hypothalamus activates the sympathetic nervous system (SNS)
  • The SNS stimulates the adrenal medulla, part of the adrenal gland
  • The adrenal medulla secretes the hormone adrenaline into the bloodstream
• Adrenaline is released from the adrenal medulla in response to activation of the sympathomedullary pathway.
• Adrenaline has a range of effects on the body

  Direct effects of adrenaline

  – increase heart rate

  – constricts blood vessels, increasing rate of blood flow and raising blood pressure

  – diverts blood away from the skin, kidneys and digestive system

  – increases blood to brain and skeletal muscle

  – increases respiration and sweating
• The general effects of adrenaline

  – prepare the body for action, fight or flight,

  – increase blood supply/oxygen, to skeletal muscle for physical action

  – increase oxygen to brain for rapid response planning
• the fight/flight response is generated by the sympathetic branch of the ANS

  • the hypothalamus stimulates the SNS

  • SNS stimulates the adrenal medulla to release adrenaline into the blood stream/endocrine system and noradrenaline is released
• • Xavier’s shaky hands may be caused by adrenaline as adrenaline increases muscle tension, causes an increase in heart rate /increases blood flow to muscles (which can cause limbs to shake)
  • adrenaline stimulates glucose to be released/increases blood sugar levels, providing more muscle fuel
  • digestion is inhibited during SNS arousal, which may explain why Xavier felt sick
  • once the stressor is gone the PNS acts to dampen the stress response and return the heart/breathing rate to resting levels/initiate digestion, etc, this may explain why after 20 mins Xavier calmed down.
• explain how the body responds during fight or flight and why this could be unhelpful in a driving test situation.

  the fight or flight response causes adrenaline to be released which can cause an increased production of sweat and faster heart and breathing rate which could be off putting and unhelpful

  (e.g. sweaty hands may make it harder to grip the steering wheel).

  the fight or flight response enable a quick reaction to fight the threat or run away from it but neither of these options would be helpful, if you ran away or attacked the instructor you would fail the test.
• the endocrine system helps to regulate the activity of cells and organs in the body

  the endocrine system communicates chemical messages to the organs of the body