fight or flight response

• where does the fight of flight response start?

  in a part of the brain called the amygdala
• what system is the amygdala in?

  limbic system
• how does the amygdala decide how to respond to environmental stimuli?

  evaluates the emotional significance of sensory information (is it harmful/scary/nice?) and triggering an appropriate response
• what happens to the amygdala when we are threatened?

  the amygdala causes the nervous and hormonal systems to work together to conduct a fast response
• why is the nervous system involved in the fight or flight response?

  the response has to be very fast, so the nervous system triggers bodily arousal by the rapid release of adrenalin from the adrenal gland
• why is the hormonal system involved in the fight or flight response?

  the active muscles and brain will run out of energy quick, so the hormonal system maintains a consistent supply of blood sugar and 'anti-inflammatory' chemicals to keep the body active as long as needed
• how does the amygdala activate fight or flight after deeming a situation threatening?

  alerting the hypothalamus
• what does the hypothalamus do after being alerted by the amygdala?

  triggers both the nervous system (SAM, the sympathomedullary pathway) and the hormonal system (HPA, the hypothalamic pituitary-adrenal pathway)
• what does the hypothalamus do to the nervous system (SAM)?

  activates the sympathetic branch of the autonomic nervous system
• what does the sympathetic branch of the autonomic nervous system do when activated?

  stimulates the medulla layer of the adrenal gland to produce adrenalin and noradrenalin which are released into the blood stream
• what does adrenalin increase?

  heart rate

  breathing rate

  blood flow to muscles & brain
• what does adrenalin decrease?

  blood flow

  activity in the digestive system

  activity in the immune system
• what does the nervous system do once the threat is over?

  the parasympathetic part of the autonomic nervous system then brings back the body to the normal optimum level of functioning
• what does the hypothalamus do to the hormonal system (HPA)?

  stimulates the pituitary gland
• what does the pituitary gland do when stimulated by the hypothalamus?

  secretes adrenocorticotropic hormone (ACTH)
• what does the adrenocorticotropic hormone (ACTH) do when stimulated by the the pituitary gland?

  stimulates the cortex layer of the adrenal gland to produce the stress hormones corticosteroids
• what does cortisol do in the hormonal system response?

  enables the body to keep steady supplies of blood sugar by releasing stored glucose from the liver for energy
• what does hydrocortisone do in the hormonal system response?

  controls swelling after injury (corticosteroids also suppress the immune system while this happens)
• why did the fight or flight response work well in prehistoric times?

  threats were physical (lions etc.) so you could fight or run away from them
• why can the fight or flight response be inappropriate in the modern world?

  threats are often psychological (exams, relationships etc.) and cannot be removed by fighting or running away which means the response continues and may damage the body, which can cause physical symptoms of stress
• what does over activation of the HPA pathway during pregnancy or early childhood do?

  affects brain development (Romanian orphans) + such changes have been linked to social, intellectual and emotional problems in later life