STRESS AS A RESPONSE- GAS MODEL

stress response

a reaction that involves the physiological (‘bodily’) and psychological (‘mental’) changes people experience when confronted with a stressor

fight or flight response

• involuntary bodily changes that occur in much the same way in all individuals when they first become aware of an acute stressor

• the body’s production of a sudden and very high arousal level for a relatively short time

acute stress response

• involves the sympathetic and endocrine system

  1. within milliseconds of perceiving a threat (an acute stressor), the hypothalamus activates the sympathetic NS

  2. the SNS then stimulates the adrenal medulla, which is the inner part of the adrenal gland

  3. the adrenal glands secrete hormones into the bloodstream including: adrenaline, noradrenaline and cortisol

what is the effect of cortisol?

• increases glucose in bloodstream, enhances the body’s use of glucose and increases the availability of substances in the body that repairs tissues

• slows non-essential functions in the body

• reduces inflammation, but suppresses the immune system

what is the GAS model

• body’s typical response pattern in terms of resistance to stress over time

• Selye proposed that a bodily mechanism called ‘adaptation’ was required to respond to both eustress and distress

• humans react to any stress by putting in motion a set of physiological responses that attempt to alleviate the impact of the stressor

stages of GAS model

stage 1= alarm reaction (shock and countershock)

stage 2= resistance

stage 3= exhaustion

what is alarm reaction?

• occurs when the organism becomes first aware of the stressor

• it prepares a person to respond to the stressor

what is shock? (alarm stage)

• resistance to stress levels fall below normal and the body acts as if it is injured

• body temp and blood pressure drop

• muscles temporarily lose tone

• the physical effects of shock reduce the organism’s ability to deal with the stressor (feel momentarily helpless)

what is countershock?

• a distress signal is sent to the hypothalamus

• hypothalamus sends a signal to the adrenal glands to secrete adrenaline and cortisol (stress hormones)

• increased heart rate, breathing rate and blood sugar

what is the effect of adrenaline

gives a boost of energy

when are the hormones released?

• all released in countershock stage

• adrenaline and noradrenaline before cortisol

what is resistance?

• body tries to stabilise its internal systems and return to homeostasis

• physiological changes from alarm reaction is counteracted by the parasympathetic nervous system

• this is because it is harmful to remain stressed so body reduces amount of cortisol produced

• heart rate and blood pressure begin to return to normal

what happens if the stressor remains during resistance?

• all unnecessary physiological processes are shut down

• corticosteroids continue to be produced to energise the body and reduce inflammation

• the body is better able to cope with the stressor, but physiological arousal and cortisol remain high, suppressing immune system

what happens in exhaustion?

• if stressor is still not dealt with, the body may reach exhaustion

• body has depleted energy resources by trying to recover from alarm reaction

• some alarm reaction changes may reappear

• body’s resistance to disease, physical and mental disorders is weak due to trying to deal with stressor for long time

• symptoms: fatigue, anxiety, nightmares