The fight or flight response

Question 1

Sympatho-medullary pathway

Answer 1

1) acute stressor detected
2) hypothalamus activated
3) sympathetic branch (SNS) of autonomic nervous system activated
4) noradrenaline released / adrenal medulla releases adrenaline
5) animal prepared for fight or flight:
stimulates organs (e.g. heart, lungs, pupils, liver) and slows digestive system
6) stressor goes and parasympathetic branch of ANS returns body to normal state

Question 2

General effects of adrenaline

Answer 2

Prepare the body for action (fight or flight)
Increase bloody supply / oxygen to skeletal muscle, for physical action
Increase oxygen to brain for rapid response planning

Question 3

Direct effects of adrenaline

Answer 3

Increased heart rate
Constricts blood vessels, increasing rate of blood flow and raising blood pressure
Diverts blood away from skin and digestive system
Increases blood to brain and skeletal muscle
Increases respiration

Question 4

The amygdala and hypothalamus

Answer 4

The amygdala associates sensory signals with emotions such as anger or fear and sends a ‘distress signal’ to the hypothalamus
The hypothalamus then functions like a command centre in the brain, communicating with the rest of the body through the sympathetic nervous system
The body’s response to stressors involves two major systems, one for acute (i.e. sudden) stressors such as a personal attack, and the second for chronic (i.e. ongoing) stressors such a stressful job

Question 5

Response to acute (sudden) stressors

Answer 5

The sympathetic nervous system - prepares the body for rapid action associated with fight or flight. It sends a signal through to the adrenal medulla, which responds by releasing the hormone adrenaline into the bloodstream
Adrenaline
The parasympathetic nervous system - dampens down the stress response when the threat has passed

Question 6

Response to chronic (ongoing) stressors

Answer 6

If the brain continues to perceive something as threatening, this second system kicks in. Once the initial surge of adrenaline subsides, the hypothalamus activates a stress response system called the HPA axis.
Hypothalamus - in response to continued threat, this releases corticotrophin-releasing hormone (CRH) into the bloodstream
Pituitary gland - On arrival at the pituitary gland, CRH causes the pituitary to produce and release adrenocorticotrophic hormone (ACTH). ACTH is then transported in the bloodstream to its target site in the adrenal glands
Adrenal glands - ACTH stimulates the adrenal cortex to release various stress-related hormones, including cortisol. Cortisol has several positive (e.g. a quick burst of energy and a lower sensitivity to pain) and negative (e.g. impaired cognitive performance and a lowered immune response) effects in the body which are important to the fight or flight response
Feedback - this system is 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

Question 7

A03 - ‘tend and befriend’ response

Answer 7

Researcher suggested that for females, behavioural responses to stress are more characterised by a pattern of tend and befriend than fight or flight
Involves protecting themselves and their young through nurturing behaviours (tending) and forming protective alliances with other women (befriending)
Women may have different responses to stress as they are primary caregivers - fleeing at any sign of danger would put a females offspring at risk

Question 8

A03 - negative consequences of fight or flight

Answer 8

Problems for modern humans arise when the stress response is repeatedly activated - e.g. increased blood pressure that is characteristic of SNS activation can lead to physical damage in blood vessels and eventually lead to heart disease

Question 9

A03 - fight or flight doesn’t tell the whole story

Answer 9

Researcher suggested that the first phase of reaction to threat is not to fight or flee, but to avoid confrontation
Most animals and humans typically display the ‘freeze response’ which is essentially stopping, looking and listening where they are hyper-vigilant, alert to the slightest sign of danger
This has an advantage because it can make you look for new information in order to make the best response for that particular threat