Physiology Of Stress Content Flashcards
What is stress?
A state of physiological or psychological strain caused by real or perceived threats that elicit themselves in the form of stressors, tending to disturb the normal functioning of the body where a fight or flight response is needed to deal with the stressor
What are the two types of stress?
Acute stress: short-term stress
Chronic stress: prolonged/ongoing stress
What are stressors?
A mismatch between the normal demands upon an individual and their ability to meet those demands e.g not being able to do something you are meant to do
What is the SAM system also known as?
The sympathomedullary pathway
What are the responses to the two types of stress?
Acute stress: SAM system
Chronic stress: HPA axis/PAS system
Outline the short term response to stress (sympathomedullary pathway)?
Sympathetic nervous system - this branch of the ANS is alerted as soon as a stressor is received from the amygdala as an emotional response
. Electrical signal sent to two endocrine glands just above kidneys. Adrenal medulla releases adrenaline and noradrenaline
. These stress hormones circulate around body and cause a physiological response that prepares the individual to deal with the stressor
How are immediate stressors dealt with?
A state of homeostasis is recovered once the threat has passed as the parasympathetic branch of the ANS returns the body to its normal resting state
What causes stress?
Stressors
What is the function of the amygdala and what is its role in stress?
It is the centre of emotional response in the brain, this is the first place a stressor’s signal sends information to before the SAM system is actiavfed
Which stress response system deals with acute stress and which one deals with chronic stress?
Acute = SAM system
Chronic = PAS system
How does the PAS system work?
. Hypothalamus releases CRF into the bloodstream to stimulate pituitary gland to release ACTH
. ACTH stimulates the adrenal cortex to release cortisol (type of corticosteroid)
What is the goal of the PAS system and how does chronic stress affect this?
The cortisol released is intended to create a negative feedback loop whereby cortisol can restore the body back to a state of homeostasis after a stressful situation by inhibiting your immune system etc.
However, if you have chronic stress, stress constantly activates the PAS to keep the body in homeostasis, meaning cortisol is constantly released and the negative feedback loop is lost as the body can’t return to its desired state of homeostasis
What diseases can come about from too much/too little cortisol?
Too much = Cushing’s syndrome
Too little = Addison’s disease
What did Hans Selye do?
. Studied the stress responses of rats when presented with stressful stimuli (e.g exposure to cold temperatures) and recorded the responses
. Selye recorded similar reactions for all of the different types of stressors,
. Long-term physical responses to these stressful stimuli were:
- enlarged adrenal gland
- shrunken thymus
Conclusion:
- stress response is general to all different types of stressors
- proposed General adaptation syndrome (GAS)
What is general adaption syndrome?
The process of adapting to a stressor goes through three stages when responding to a stressful situation.
What is the biggest problem with general adaptation syndrome?
It claimed that the bodies’ physiological response to a stressor was non-specific and the same for all stressors
What are the 3 stages of GAS?
- Alarm stage: immediate fight/flight response shortly after stressful event
- Resistance stage: ANS resists the impact of stressful situations
- Exhaustion stage: if stressor continues, body fails to cope with the distressing stimulus
The exhaustion stage only occurs in chronic stress
What occurs during alarm reaction in GAS?
. As a threat is perceived, the parallel processes producing cortisol and adrenaline prepares the body in many ways for F/F
What is the resistance stage in GAS?
. Parasympathetic branch of ANS takes over as body tries to cope with stress
. Body appears to have returned to a state of homeostasis
When does the resistance stage of GAS fail?
If stress hormones are continually being released at an increased level and so the parasympathetic nervous system can’t restore the body to a state of homeostasis
What happens during the exhaustion stage of GAS?
. When a stressor persists and can’t generate resources to fight stress at the same speed that they are being used
. Adrenal glands struggle to function normally and thymus may shrink
. If the stress continues, the parasympathetic nervous system can fail and the immune system becomes vulnerable
Which type of stress is the exhaustion stage unique to?
Chronic stress
