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HPA axis
3.30.07
42
Other
Not Applicable
04/01/2007

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Cards

Term
where is the seat of the HPA?
Definition
hypothalamus
Term
what are the physiolgoical responses to stress?
Definition
activation of the HPA and the SNS
Term
What does HPA stand for?
Definition
Hypothalamic Pituitary Adrenal Axis
Term
What IS the HPA axis?
Definition
the neuroendocrine regulation of the digestive, immune, mood, sex, energy usage
Term
what is the HPA cycle?
Definition
Paraventricular nucleus of the hypothal. secretes vasopressin and CRF from the medial eminance. VP and CRF stimulate the secretion of ACTH in the pituitary. ACTH stimulates the adrenal cortices which stimulate (by ACTH) glucocorticoids and catecholamines
Term
what is cortisol?
Definition
a glucocorticoid, a sterioid hormone
Term
What is the pathway for GR signalling?
Definition
GR is intracellular (in cytoplasm, bound by protien, in inactive state). Cortisol comes through the membrane, binds, produces active molecules. 2 molecules dimerize. Binds actively to DNA and transcribes. Cortisol and GR--> binds to GRE in the promotor region.
Term
what does GRE stand for?
Definition
Glucocorticoid Response Element
Term
What are the 2 types of cells that respond to MR?
Definition
aldosterone responsive cells and aldosterone non-responsive cells
Term
Does MR have high affin or low affin for GCs?
Definition
High
Term
What does MR do?q
Definition
It is important in proactive maintanence of basal HPA tone (for a steady base state of cortisol in the blood)
Term
Is GR for low or high affinity for GCs?
Definition
Low
Term
What are GRs responsible for?
Definition
reactive NEGATIVE feedback during peak expresssion
Term
What is MR?
Definition
mineralocorticoid Receptor:: an aldosterone receptor
Term
WhaT is the adaptive stress response?
Definition
increase arousal, increase scanning attention, decrease memory, energy mobilization
Term
What is the pathological stress response?
Definition
sleep disturbance, attention disruption, memory loss, hypertension, clotting, functional bowel syndrome, sexual disorders, susceptibility to infection.
Term
What are the effects of GCs?
Definition
Alter metabolism to make glucose available and keep up stores (converts food sources into glycogen or fat, conversion of protein to fat, decreases insulin sensitivity);;

Trafficking of immune cells (changes texture of immune cells to stick to vessel wall). Inhibits immune and inflammatory reactions.

Inhibits pituitary gonadotropins, makes target tissues resistant to gonadotropins;;

Inhibits osteoblastic activity; decrease bone mass;;

Effects on hippocampus to alter memory;;

Feedback regulation of HPA axis;;

Maintain fluid balance (aldosterone in kidney)
Term
What is the adaptive response of CC?
Definition
reduced gonadotrophic activiy, immunie cell production and function, osteoblastic activity, INCREASED attention, immune cell trafficking
Term
What are the effects of CC (an allosteric load)?
Definition
REDUCED reprofuctioning, memory, growth, INCREASED infection, osteoporosis, fat, diabetes, muscle wasting
Term
When does GR regulate diurnal rhythms?
Definition
0.5 hours after waking up--gets you going!
Term
When are cortisol levels at their highest?
Definition
0.5 hours after waking up
Term
When does MR regulate?
Definition
the rest of the day
Term
what regulates CRF?
Definition
GC provides feedback regulation
Term
Where is CRF regulated?
Definition
hippocampus, amygdala, BNST, prefrontal cortex
Term
What does CRF stand for?
Definition
corticotrophin relaeasing Factor
Term
what might increased GC concentrations do?
Definition
atrophy of hippo due to stres is due to high concentrations of GC-- decrease hippo, decrease memory
Term
Where is CRF released from?
Definition
Hypothal, influenced by stress, cortisol blood levels
Term
What does CRF do?
Definition
It starts a HPA response
Term
What receptors does CRF bind to?
Definition
CRF-R1 ONLY
Term
What refcpetors does urocortin bind to?
Definition
CRF-R1 and CRF- R2
Term
Why is urocortin so important?
Definition
it binds to both
Term
What does the median eminance secreate?
Definition
CRF --> ACTH secretion
Term
Posterior Pituitary?
Definition
AVP, OT --> pressor, anitdiuretic, lactation, parturition
Term
autonomic?
Definition
CRF, AVP, OT --> transmitter/modulators in central autonomic pathways
Term
what are the effects produced by stress and central CRF administration?
Definition
Increased Sympathetic activity:
Increase heart rate, blood pressure, oxygen consumption;;
Alterations in GI function :
Decrease in upper GI motility, decrease gastric acid secretion, increase in lower GI motility, mucin depletion, decreased muscosal blood flow, mast cell degranulation;;
Cognitive Effects ::
Increase arousal, memory, seizures::
Alterations in Behavior ::
Change in locomotor activity, decrease feeding, reproductive behavior, promote anxiogenic behavior;
Immunological Effects :
Decrease killer cell activity;
Supression of Growth hormone
Term
What are the depressed HPA changes?
Definition
Hyperactive HPA system ;
Chronic elevated CORT ;
Loss of circadian rhythm;
Fail to suppress in Dex suppression test; all of which normalize when symptoms normalize
Term
What does the DEX suppression test exmaine?
Definition
the function of the HPA system
Term
What are the cortisol levels for depression
Definition
higher basal cortisol, less feedback inhibition
Term
What are the physiological symptoms of depression that mimic stress?
Definition
Hypercortisolemia
Increased Cortisol response to stress
Adrenal hypertrophy
Hyperarousal (sleep disturbance)
Anorexia
Decreased libido
Anxiety
Functional bowel disorders
Osteoporosis
Term
Are CRF levels decreased or increased in depression?
Definition
elevated, and receptors are down regulated in suicide
Term
What are cortisol levels in PTSD?
Definition
hypocortisol and supersupression to Dex
Term
Early trauma/abuse --?
Definition
mental illness, obesity, diabetes, heart disease.
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