Adrenal Catacholamines Flashcards
the adrenal gland is
two distinct organs - cortex and medulla that is organized into a single gland (not true for some species- amphibians and fish)
the cortex is split into …
3 layers
medulla contains what hormones
epi and norep
what are medulla chromaffin cells or pheochromocytes?
secretory vesicles containing epi or norepi
another name for chromaffin cell
modified neuron
what divisions of the autonomic NS involved in homeostasis?
parasymp, symp, and enteric ns
what is the role of the enteric nervous system
controls digestive organs and is mostly independent of CNS input. communicates via symp and para pathways
what are the components of the sympathetic NS?
interconnected neurons that transmit signals to postganglionic neurons.
what do the postganglionic neurons secrete?
norepi (NE) as an NT to stimulate innervated tissues
what is the role of the adrenal medulla in the symp NS?
symp NS innervates the adrenal medulla, which secrtes epi (E) into the bloodstream. this circulates to tissues targeting α- or β-adrenergic receptors (α-AR or β-AR).
how is secretion of epi and norepi stimulated?
by acetylcholine, which activates nicotinic receptors
what casues serum norepi concentrations?
primarily due to sym nerve leakage
what is the NT involved in transmitting signals within the symp NS?
acetylcholine, particularly in preganglionic neurons
what are the steps of catecholamine synthesis?
- acting on tyrosine; tyrosine hydroxylase adds a hydroxyl group to make DOPA (rate limiting step)
- dopa to dopamine: enzyme in all tissues removes carboxyl; drugs that block can cause production of ‘false transmitters’
- dopamine enters storage vesicles
- hydroxyl added to make norepi
- diffuses to cytoplasm - to make epi: methyl added by PNMT -> epi
- mostly occurs in adrenal medulla chromaffin cell
whats PNMT?
phenylethanolamine N-methyltransferase, gene induced by cortisol
