Flashcards in HPA Axis and Adrenal Gland Deck (80)
What are the components of the HPA axis?
What are the main functions of the HPA axis?
-Adaptive response to stress
-Regulation of immune function
What are the hormones of the HPA axis?
Catecholamines – epinephrine and norepinephrine
Glucocorticoids – cortisol
What enacts short loop inhibition on CRH?
What enacts long loop inhibition on CRH?
Where is CRH made?
Parvocellular Neurons of the PVN
What is the release pattern of CRH?
Pulsatile so it results in periodic release of ACTH
What receptor does CRH use for the release of ACTH?
What are the main receptors that bind CRH and what is the binding affinity?
CRH R1 - Binds with highest affinity to CRH R1 in anterior pituitary.
CRH R2 - Binds with higher affinity to urocortin.
What is the synergistic effect of CRH and AVP?
ACTH release is amplified in the presence of AVP and CRH together
What is POMC?
Pro-opiomelanocortin and it is the precursor of ACTH
Where is ACTH made?
What receptors does ACTH bind to and with what affinity?
Binds with high affinity to MC2R
Binds with low affinity to MC1R (skin)
How do high levels of ACTH causes hyper pigmentation of the skin?
It will increase MC1R binding in the skin
What are the 3 layers of the adrenal gland?
What hormones does the cortex secrete??
What hormones does the medulla secrete?
What is the cell type of cortex and the medulla?
Cortex - glandular
Medulla - neural
What are the 3 layers of the adrenal cortex and the hormones that they produce?
Zona Glomerulosa - Mineralcorticoids
Zona Fascilculata - Glucocorticoids
Zona Reticularis - Weak Androgens (DHEA)
What is the blood supply of the adrenal cortex?
Suprarenal arteries break into subcapsular plexus of capillaries (fenestrated).
What is the blood supply of the adrenal medulla?
It has a dual blood supply.
•Bathes the medullary cells with blood carrying corticosteriods from the cortex – important for conversion of NE to E.
•Arterioles break into fenestrated capillaries.
What is cortisol released in response to?
Where is cortisol released from?
How is cortisol transported in the blood?
90% is bound to corticosteroid binding globulin (CBG)
What converts cortisone into cortisol?
What is pleiotropy in cortisol?
It has different effects on different tissues.
What is the effect of cortisol on bone?
Increases bone resorption and decreases bone formation by decreasing IGF-I receptors.
What is the effect of cortisol on muscle?
Decreases muscle mass
What is the effect of cortisol on the immune system?
Suppresses immune and inflammatory responses