Introduction to Stress Flashcards
What is a Stimulus in stress?
Stressor
What is a Response to stress?
Strain
What is the process of stress?
Interactions between stimulus and response
What are two definitions of stress?
- “A physical or emotional factor that causes bodily or mental tension and may lead to disease causation”
- “A negative emotional experience accompanied by biochemical, physiological, cognitive and behavioral changes that are directed toward altering the stressful event.”
What is physical stress?
A direct physical threat to one’s well-being - cold, heat, infection, extended exercise, etc.
What is psychological stress?
An event that is perceived as negative (not physically threatening) —> Loss of a loved one, major personal disappointment, unemployment
What are two pathways that work in response to stress?
- Sympathetic-Adrenal-Medulla (SAM) axis
2. Hypothalamus-Pituitary-Adrenal (HPA) axis
What happens in the Sympathetic-Adrenal-Medulla axis in response to stress?
- Prepares organ to respond to state of emergency
2. Adrenal medulla secretes catecholamines (NE and EPI)
What happens in the Hypothalamus-Pituitary-Adrenal (HPA) axis in response to stress?
- Corticotropin-Releasing Hormone (CRH)
- Goes to anterior portion of pituitary gland
- Releases ACTH (Adrenocorticotropic Homrone)
- Adrenal cortex produces cortisol (glucocorticoid hormone)
- Normal metabolic functions and efficiency under state of emergency (energy utilization)
What does the diagram of the HPA axis show?
- Circadian Rhythm disruptions or Stress cause the release of…
- CRH which leads to the release of…
- ACTH which leads to the release of…
- Cortisol
What are the functions of Cortisol from the HPA diagram?
- Negative feedback upon ACTH and CRH
- Suppresses immune system function
- Causes gluconeogenesis in the liver (producing glucose)
- Causes protein catabolism in the muscle (producing a.a.)
- Causes lipolysis in the adipose tissue (producing fat particles)
How can cortisone inhibit immune functions?
- Dec. macrophage response to IL-2 or interferon-g –> Dec. macrophage cell ingestion
- Dec. IL-1 production by macrophages –> Dec. IL-2 production by T cells
- Dec. production of CD4 cells
- Dec. activity of B lymphocytes –> Dec. activity of NK cells
What three main things did Walter Cannon describe (1871-1945)?
- Homeostasis
- Allostasis
- Fight-Flight Response
What is Homeostasis?
The collective process of maintaining the internal physiology stability in the face of environmental change
What is Allostasis?
(Refinement of homeostasis): the compensation that an organism does to achieve homeostasis successfully
- -> Brain is able to detect non-optimal internal states & it can use lots of mechanisms to compensate correctly
- -> Failure to meet such challenges of homeostasis can result in tissue damage or death
What is homeostasis a dynamic balance between?
The autonomic branches
- Stress –> sympathetic activity dominants –> fight or flight
- Normal resting condition –> parasympathetic activity dominates –> rest and digest
What is the Fight-Flight Response?
- Organisms better equipped to defend themselves would have a survival & evolutionary advantage over those less equipped
- The term “fight-flight response” is used in reference to this loosely defined constellation of survival functions
- Fight-flight response is a prototype stress response
- Fight-flight response incorporates powerful emotional (anxiety, fear, anger), neuroendocrine and autonomic changes to increase chance of survival
What was Hans Selye’s contribution?
He proposed a general model of stress reactivity which described physiological mechanisms for the stress-illness relationship