fight or flight

• When faced with a threat, the amygdala is mobilised. The amygdala associates sensory signals with emotions linked to the fight or flight. The distress signal is sent to the hypothalamus and communicates it through the body by the somatic nervous system (SNS). The body has acute (sudden) and chronic stresses (ongoing). When the SNS is triggered, starts process of preparing body for fight or flight. This sends a signal through adrenal medulla which puts adrenaline into the blood. Adrenaline circles the body causing psychological changes (heart rate).
• When the threat has passed, the parasympathetic nervous system comes into play. This dampens down the stress response. For example, it slows down the heart rate and reduces blood pressure. If the brain continues to perceive something as threatening, a second system kicks in.
• As the initial surge of adrenaline subsides, the hypothalamus activates a stress response system called the HPA axis. The hypothalamus (H). In response to the continued threat, it releases a chemical messenger CRH which is released into the bloodstream. The pituitary gland (P). When CRH reaches this gland, it causes the glad to produce and release ACTH which is transported through the blood stream to the target of the adrenal glands. Adrenal glands (A). This stimulates the release of various stress-related hormones including cortisol
• Cortisol is responsible for several effects in the fight or flight response. Some are positive eg quick burst of energy or negative eg impaired cognitive performance. There is also a feedback system included where if receptors monitoring cortisol levels, if they go above normal it creates a reaction in CRH and ACTH levels to go back to normal.
• An issue is the gender bias in this theory.

  It was found that, for females, a tend and befriend response can happen which was ignored by researchers studying the fight or flight which creates a beta bias. Women may have different a different system in coping with stress due to the responses that have evolved due to usually being the primary caregiver of children.

  This suggests that we must be carefully generalising all the findings to everyone as there may be differences that have been overlooked or ignored.
• The responses associated with fight or flight may be adaptive for stress response, however in modern life this is hardly required to create such levels of physical activity.

  The problem for modern humans arises when the stress response is repeatedly activated. For example, the increased blood pressure can lead to physical damage in blood vessels and eventually lead to heart disease.

  As a consequence too much cortisol suppresses the immune response shutting down the process that fights infection and increasing the likelihood of stress-related illness.
• A criticism is that fight or flight doesn’t tell the whole story.

  Gray suggests that, prior to responding with attacking or running away, most animals typically display the ‘freeze’ response. This is essentially a ‘stop, look and listen’ response to be alert to the slightest signs of danger.

  The adaptive advantage of this response for humans are that freezing focuses attention and makes them look for new information to create the best response for the situation.
• A genetic basis for gender differences in fight or flight response was found.

  The SRY gene, found in the male Y chromosome directs male development, promoting aggression and resulting in the fight or flight response. This gene may prime males to respond to stress in this way by the release of stress hormones such as adrenaline.

  The absence of this gene in females may prevent this response to stress, leading to the ‘tend and befriend’ behaviours.