Endocrinology of Stress Flashcards
wk 12
Eustress
normal physiologic workings of the living organism
Pathogenic stress or distress
when homestasis threatened or perceived to be so in setting of overwhelming or sustained external and internal stressors
What are the two components of the stress system?
Central and peripheral
Describe the central component of the stress system
Hypothalamus and brain steam
CRH and ADH secreting neurons of the hypothalamus
Noradrenergic cell groups in medulla and pons
Peripheral components
Peripheral limbs of HPA axis
Efferent sympathetic-adrenal medullary system
Components of the parasympathetic system
What are the two overall axis for Hypothalamus - pituitary - adrenal axis?
Hypothalamus (CRH + AVP) –> Anterior pituitary –> ACTH –> Adrenal cortex –> Cortisol
Hypothalamus –> sympathetic nervous system –> Adrenal Medulla
What are the three stress hormones?
Corticotropin releasing hormone
Adrenocorticotropic hormone
Glucocorticoids
Describe the release of CRH
Increased pulsatile release early in morning = increased primary amplitude of ACTH and cortisol secretion
Name some other hormones changes during stress
Oxytocin increase
glucagon increase
epinephrine increase
Angiotensin increase
Insulin decrease
What are the receptors for CRH?
CRHR1 and CRHR2
What is the primary regulator of the HPA?
CRH
What functions does the ANS control in regards to stress?
Cardiovascular, respiratory, GI, renal and endocrine
What are the effects of cortisol on growth?
Increased HPA axis = decreased GH
Prolonged cortisol presence = supression of growth hormone
Cortisol induced inhibition of IGF-1
CRH increases somatostatin
Chronic stress = supressed growth
In Cushing’s syndrome: delayed growth and shorter overall height
Describe the relationship between stress and thyroid hormone.
Stressed induced cortisol = decreased levels of TSH and inhibition of T3 and T4 formation
Due to increased CRH-induced somatostatin and cortisol
Describe the effect of stress on reproduction
Inhibited by ALL aspects if HPA axis
Decreased GnRH secretion = increased resistance od gonadal tissue
Ovarian and testicular steroidogenesis inhibited
What can happen in cases of chronic stress?
all functions of immune system is decreased
there can be a slight shift towards adaptive = potentially detrimental changes
What can happen in cases of acute stress?
Shift towards innate immune response
What is the impact of cortisol on immune system?
Anti-inflammatory and immunosupressive effect
Describe the overall effect of cortsiol in metabolism
Direct catabolic effects
Outline general effects of stress on metabolism.
Direct catabolic effects
Glucocorticoids antagonise the metabolic actions of GH and sex steroids
Chronic stress= increased gluconeogenesis, increased visceral adiposity, decreased bone and muscle mass, decreased osteoblastic activity and insulin resistance. -
What are the three reactions in General Adaption Syndrome?
Alarm reaction (shock stage
Stage of resistance (counter shock)
Stage of exhaustion
Describe the actions and effects of the Alaram reaction stage of General adaptive syndrome.
Generalised stimulation of the sympathetic nervous system = release of catecholamines
Increased sympathetic-adrenal action = increased HR, constriction of blood vessels to viscera and skin, blood supply to heart and muscles, BP and glycogenolysis
decreased digestive and reproductive system.
What occurs in the stage of resistance (2nd stage of GAS)
Body adapts to stress (system changes to reduce stress effects)
What hormone acts in the stage of resistance (2nd stage of GAS) and what effect does it have?
Cortisol
lipolysis, gluconeogenesis, protein catabolism, increased blood vessel sensitive and decreased inflammation.
