Stress Flashcards
Cannon’s concept of homeostasis
&
fight or flight responses
Stress response:
- Posterior pituitary –> ACTH –> adrenal gland –> cortisol –> increase glucose (prevent hypoglycemia)
- Rapid response: sympathetic NS –> adrenal gland–> NE & E –> î HR, respiration, blood flow, muscle strength
*homeostasis: negative feedback of cortisol
CRF as a neurotransmitter:
behavioral effects (6)
- increases locomotor activity
- startle response
- responsiveness to stress
- anxiogenic-like effect: helps to focus
- dose-dependent facilitation of stress-induced fighting
- taste and place aversion –> conscious uneasy feeling
Immune system (3)
- Chronic glucocorticoids have inhibitory effect on immune system
- Cytokines (IL) are pro-inflammatory molecules that increase production of CRF
- Cytokines from brain and peripheral can inhibit: FSH, LH, PRL, GH, TH –> decreased sex drive and fertility
*some immune cells can block effect of high cortisol to produce cytokines
cardiovascular response (4)
- Constant stimulation of smooth muscles by sympathetic nervous system –> increase activity
- Muscles get larger in size and number: hypertrophy
- Narrows lumen of blood vessel
- In addition to build up of plaque & put in a stressful situation (new; sensitized) –> catecholamine surge (NE) –> vasoconstriction –> heart attack (stops blood flow to heart)
respiratory response
Gonads: Polycystc Ovary Syndrome (PCOS)
(3)
- Cortisol –> hyperglycemia –> hyperinsulinemia
- insulin acts on ovarian stroma –> increase in androgen synthesis (excess)
- Hirsutism, virilization, anovulation
*failure to produce normal estrogen; disrupts LH and FSH secretion
gastrointestinal response
- Decreases stomach contractility and emptying –> bloating and full feeling
- Increases colon motility, transit, and defecation –> diarrhea
- Chronic: sloughing on intestinal epithelial lining –> large food particles can penetrate gut wall and interact with immune cells –> body generates antibodies to food –> allergies
Chronic exposure to stress (5)
- Chronic stress leads to depression
- Cushing-like features (cortisol stimulates mineralocorticoid R)
- weight gain due to increase in NPY –> hunger
weight gain leads to insulin resistance
- Length component of stress:
a. Sustained increase in HPA axis
b. Overtime, desensitization: decrease in HPA axis - Lose resilience to reutrn back to normal levels; decreases with age
Life expectancy
Chronic stress reduces telomere length –>
lose structural integrity for cells to replicate and divide
*potentially caused by oxidative damage –> premature cell death –> biological aging
*Decreasing stress, low fat diet, aerobic exercise, and group support can increase telomerase activity in PBMC
Habituation & Sensitization
Habituation: body downregulates response
decrease in behavior/body change due to chronic stimulation as seen in chronic stress
Sensitization: bodily response to a new stimulus
Role of stress in development of diseases
- hypertension
- endocrine disorders
- immune system disorders
- Smooth muscle hypertrophy and increase in size narrows lumen; stress upregulates renin-angiotensin system in kidneys via the sympathetic NS
- Lose negative feedback b/c demand for cortisol continues to increase
- Suppress all parameters of immune system; more susceptible to sickness
Neuroendocrine systems
