U1 day 7 stress Flashcards
(12 cards)
HPA axis steps for response
Paraventricular hypothalamus releases CRH, Portal circulation to Anterior pituitary, release of ACTH from Ant. Pituitary, systemic circulation, Adrenal cortex synthesis and release of corticosteroids, systemic circulation, central and peripheral NS actions, Feedback
Stress Appraisal
Limbic regions (prefrontal cortex, hippocampus, and amygdala) innervate hypothalamus and brainstem to convey psychosocial influences.
T/F CRH neurons receive direct synaptic inputs from brain regions that mediate memory and cognition.
False, not direct input, they act on homeostatic regions that then have a direct input into CRH neurons.
Corticotropin releasing hormone (CRH)
peptide synthesized by neurons of paraventricular hypothalamus
CRH receptor 1
CRH-R1 primary CRH receptor expressed by corticotropes, simulates HPA axis, GPCR signaling through G-alpha-S.
CRH receptor 2
CRH-R2 has low affinity for CRH, reduces stress response.
Adrenocorticotropic Hormone (ACTH)
Synthesized from precursor Proopiomelanocortin (POMC), then stored in vesicles, rise in intracellular calcium leads to exocytosis.
Adrenal Cortex synthesis of hormones
mineralocorticoid (Zona Glomerulosa)
glucocorticoid, cortisol (Zona Fasciculata)
androgens - testosterone (Zona reticularis)
ACTH receptors
Melanocrotin-2 receptor (MC2R), located in all three layers of adrenal cortex, activates cAMP and PKA through GCPR and G-alpha-S, to increase cholesterol intake into mitochondria
T/F Pituitary receptors for CRH (CRH-R1) and Adrenal cortex receptors for ACTH (MC2R) both signal through G-alpha-S coupled receptors to increase PKA activity
true
Steroidogenesis
all arise from cholesterol, synthesized on demand and not stored, lipophilic, diffuse through membranes
Corticosteroid receptors
Type 1: MR: high affinity: binds at lower concentrations
Type 2: GR: lower affinity than MR: activated by elevated cortisol, only binds when MR is full
