Noradrenergic nerve terminal Norepinephrine production adrenergic neurons transport tyrosine by a transport protein to synthesize norepinephrine adrenergic and dopaminergic neurons use the same pathway adrenergic neurons modify NE to Epi dopaminergic neurons terminates at dopamine tyrosine → dopa → dopamine → norepinephrine → epinephrine the rate limiting step is the conversion of tyrosine to dopa by tyrosine hydroxylase can be inhibited by metyrosine NE pathway feedback NE: negative feedback by acting on presynaptic α2 autoreceptors to inhibit further NE release ACh: acts on M2 receptors also to inhibit further NE release angiotensin II: activates NE release Pathway Inhibitors reserpine: inhibits the vesicular monoamine transporter (VMAT) preventing the storage of neurotransmitters guanethidine: replaces the NE inside the neurotransmitter vesicles and depletes the vesicle of NE cocaine and tricyclic antidepressants: inhibits the NET (reuptake) Cholinergic Nerve Terminal Acetylcholine (ACh) production synthesized from choline and acetyl-CoA by choline acetyltransferase acetyl-CoA is made in the mitochondria choline is transported into the nerve by choline transporter (CHT) Pathway Inhibitors hemicholinium: blocks the uptake of choline by inhibiting CHT vesamicol: inhibits vesicular acetylcholine transporter (VAT) preventing the storage of acetylcholine botulinum toxin: cleaves the SNAP proteins thereby preventing the presynaptic vesicles from docking at the terminal and releasing acetylcholine
QUESTIONS 1 of 3 1 2 3 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.PH.12.40) A 32-year-old farmer is brought to the emergency department by his wife. The patient was reportedly anxious, sweaty, and complaining of a headache and chest tightness before losing consciousness en route to the hospital. Which of the following is mechanistically responsible for this patient's symptoms? QID: 101704 Type & Select Correct Answer 1 Competitive inhibition of acetylcholine at post-junctional effector sites 10% (46/449) 2 Binding of acetylcholine agonists to post-junctional receptors 9% (42/449) 3 Inhibition of presynaptic exocytosis of acetylcholine vesicles 6% (26/449) 4 Irreversible inhibition of acetylcholinesterase 53% (238/449) 5 Reversible inhibition of acetylcholinesterase 19% (84/449) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic
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