the fight or flight response

• the amygdala associates sensory signals w/ emotions such as anger of fear and sends a 'distress signal' to the hypothalamus
• the hypothalamus in response to continued treat releases CRH into the bloodstream
• the pituitary gland releases ACTH into the bloodstream and from there to its target sites
• the SNS prepares the body for the rapid action associated w/ fight or flight
• the PNS dampens down the stress response when the threat has passed
• the adrenal medulla releases adrenaline into the bloodstream causing physiological changes such as increased heart rate and release of blood sugar
• the adrenal cortex releases stress hormones including cortisol in response to stress
• the feedback system cortisol levels are monitored so that CRH and ACTH production is inhibited if cortisol is too high
• the amygdala + hypothalamus: when a person is faced w/ threat, an area of the brain called the amygdala is mobilised, the amygdala associates sensory signals (what we see, hear or smell) w/ emotions associated w/ fight or flight such as fear or anger
• the amygdala + hypothalamus: the amygdala then sends a distress signal to the hypothalamus which functions like a command centre in the brain communicating w/ the rest of the body through sympatheic nervous system
• the amygdala + hypothalamus: the boy's response to stressors involves 2 major systems one for acute (sudden) stressors such as personal attack and the second for chronic (ongoing) stressors such as a stressful job
• the sympathetic nervous system: when the sympathetic nervous system (SNS) is triggered it begins the process of preparing the body for the rapid action necessary for fight or fight
• the sympathetic nervous system: the SNS sends a signal through to the adrenal medulla which responds by releasing the hormone adrenaline into the bloodstream
• adrenaline: as adrenaline circulates through the body it causes a number of physiological changes, the heart beats faster, pushing blood to the muscles, heart and other vital organs and blood pressure increases
• adrenaline: breathing becomes more rapid in order to take in as much oxygen as possible with each breath, adrenaline also triggers the release of blood sugar (glucose) and fats which flood into the bloodstream supplying energy to parts of the body associated w/ the fight-or-flight response
• the parasympathetic nervous system: when the threat is passed the parasympathetic branch of the autonomic nervous system (ANS) dampens down the stress response, whereas the sympathetic branch causes the heart to beat faster and blood pressure to increase the parasympathetic branch slows down the heartbeat again and reduces blood pressure
• the parasympathetic nervous system: another benefit of parasympathetic action is that digestion (inhibited when the SNS is aroused) begins again
• response to acute stressors include the SNS, adrenaline and the PNS
• response to chronic stressors are the hypothalamus, the pituitary gland and the adrenal glands
• response to chronic stressors: if the brain continues to perceive something as threatening the second system kicks in, as the initial surge of adrenaline subsides the hypothalamus activates a stress response system called the HPA axis
• response to chronic stressors: the HPA axis consists of the hypothalamus, the pituitary gland and the adrenal glands
• 'H' - the hypothalamus = the HPA axis relies on a series of hormonal signals to keep the SNS working, in response to continued threat the hypothalamus releases a chemical messenger, corticotrophin-releasing hormone (CRH) which is released into the bloodstream in response to the stressor
• 'P' - the pituitary gland = on arrival at the pituitary gland, CRH causes the pituitary to produce and release ACTH from the pituitary ACTH is transported in the bloodstream to its target site in the adrenal glands
• 'A' - adrenal glands = ACTH stimulates the adrenal cortex to release various stress-related hormones, including cortisol, cortisol is responsible for several effects in the body that are important in the fight or flight response, some of these are positive (e.g. a quick burst of energy and a lower sensitivity to pain) whereas others are negative (e.g. impaired cognitive performance and a lowered immune response)
• feedback: this system is also very efficient at regulating itself, both the hypothalamus and pituitary gland have special receptors that monitor circulating cortisol levels, if these rise above normal they initiate a reduction in CRH and ACTH levels thus bringing cortisol levels back to normal
• evaluation L: Taylor et al (2000) suggests that for females behavioural responses to stress are more characterised by a pattern of tend and befriend than fight or flight = this finding explained in terms of the higher levels or hormone oxytocin in females suggests that previous research which has mainly focused on males had obscured patterns of stress response in females
• evaluation L: Gray argues that the 1st phase of reaction to a threat is not fight or flee but to avoid confrontation, he suggests that there's a 'freeze response' , that its not just broken down into fight or flight
• evaluation S: Lee and Harley (2012) found evidence of a genetic basis for gender differences in the fight or flight response - the absence of the SRY gene in females (who do not have a Y chromosome) may prevent this response to stress leading instead to 'tend and befriend' behaviours