Physiology of stress

sympathomedullary pathway
1. controls how the body initially responds to an acute stressor - triggers the sympathetic nervous system
2. Short term response - fight or flight
3. triggers the fight or flight response including the hormones adrenaline and noradrenaline which communicate with target organs in the body such as the heart.
4. The hypothalamus also activates the adrenal medulla. The adrenal medulla is part of the autonomic nervous system (ANS).
5. adrenaline and nordrenaline targrts the heart
hypothalamic-pituitary-adrenal system
1. controls how the body responds to a chronic stressor
2. The stressor activates the Hypothalamic Pituitary gland
  1. The pituitary gland secretes adrenocorticotropic hormone (ACTH)
    1. ACTH stimulates the adrenal glands to produce the hormone cortisol
General Adaption Syndrome
1. Selyes
  1. Selyes model was based on his observations working with human patients - selye noticed they all shared a common set of symptoms; aches and pains, loss of appetite.
    1. This was also done with rats, no matter what noxious substance they were injected with they produced similar responses
2. 3 stages
  1. alarm stage
    1. activates its fight or flight response system, and releases the “stress” hormones such as adrenaline, noradrenaline and cortisol.
  2. resistance stage
    1. After the body has responded to the stressor, it is more likely that the stress level has been eradicated, or simply reduced. What happens next to the fight or flight response is that you body’s defences become weaker, as it needs to allocate energy to the repair of damaged muscle tissues and lower the production of the stress hormones.
  3. exhaustion stage
    1. During this phase, the stress has been persistent for a longer period. The body starts to lose its ability to combat the stressors and reduce their harmful impact because the adaptive energy is all drained out. The exhaustion stage can be referred to as the gate towards burnout or stress overload, which can lead to health problems if not resolved immediately.
3. However more recent research shows that many resources (sugar, neurotransmitters, hormones and proteins) do not become depleted even under extreme stress. the current view is that the exhaustion phase in associated with increased hormone activity, such as cortisol, and it is this rather than the depletion of resources that leads to stress-related illness
Key words
1. cortisol
  1. General adaption syndrome
    1. Hypothalamic-pituitary-system
      1. sympathomedullary pathway
        acute
        chronic
        Immunosuppression
        is when stress can cause illness by preventing the immune system from working effciently and carrying out it’s usual task of identifying and desroying pathogens
        is the body's response to long term stress
        the body's immediate response
        regulates short term stress
      2. regiuates long term stress
    2. a 3-stage set of physiological processes which prepare, or adapt, the body for danger.
  2. is an important hormone produced by the adrenal cortex . it helps the body to cope with stressors by controlling how the body uses energy. Cortisol suprreses immune system activity.
evaluation of the physiology of stress
1. There is a male bias in biological research
  1. female responds with fight or flight this creates a risk for her children because it leaves them vulnerable
    1. More adaptive in females is the tend and befriend
      1. The assumption fight or flight is a valid explanation of the stress response in all humans is a reflection of bias towards male physiology.
2. Physiological factors are ignored
  1. physiological accounts on the stress response ignore psychological factors such as cognitive appraisal. Richard Lazarus (1999) argues that we make appraisals of a stressor by actively working out if it is a threat (primary appraisal) and whether we have the resources to cope with it (secondary appraisal)
3. Speismen at al
  1. asked students to watch a primitive and gruesome medical procedure on film whilst their heart rates were monitored.
    1. If they believed the procedure to be traumatic, their heart rates increased,
    2. voluntary and joyful rite of passage, their heart rates decreased
    3. It shows that humans are not as passive in the face of stressors as physiological theories assume.
4. There are real life benefits
  1. Addison disease is a rare disorder of the adrenal glands, in which sufferers cannot produce cortisol
  2. mental confusion, abnormal heart rhythm and a catastrophic drop in blood pressure.
  3. Patients can lead relatively normal lives
The physiological response
1. acute stress
  1. fight or flight
    1. sympathetic arousal
      1. when a stressor is threatening, symapthetic branch is activated by the hypothalamus, connect brain with organs including heart and adrenal glands
      2. Adrenal medulla
        ... and adrenal cortex (surround medulla)- release hormone
        adrenaline and noradrenaline
        heart beats faster, muscle tense and the liver converts stored glycogen into glucose for energy
        End of response
2. Chronic stress
  1. activated by the HPA which takes loner than the SAM, lasts longer
    1. when activated, it sends a signal to the symapthetic ns and produces corticotropin releasing factor
      1. causes the release of ACTH

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	Criado por Lilly Clare quase 8 anos atrás