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AutonomicsI&II
lectures 3-4 mumby
Question | Answer |
---|---|
parasympathetic - long PREsynaptic, short postsynaptic | |
sympathetic - short presynaptic, long postsynatpic | |
greater splanchnic nerve innervates sympathetic to adrenal medulla | |
NT at all autonomic ganglionic synapses | acetylcholine |
NT at symp. effector junction | mostly NE thus adrenergic |
NT at parasymp. effector junction | always ACh thus cholinergic |
Choline is actively transported into neuron then combined with _____ to make ACh via the enzyme _______. | acetylCoA; choline acetyltransferase (ChAT) |
toxin that blocks exocytosis of ACh, causing flaccid paralysis | botulinum toxin A |
toxin that causes massive release of exocytic vesicles containing ACh | alpha-latrotoxin from black widow spider |
pseudocholinesterase | aka butyrylcholinesterase, a non-specific cholinesterase found in liver & in plasma; metabolizes mostly exogenous choline compounds |
first-known naturally occurring agonist and antagonist of the nicotinic receptors | nicotine/ACh and curare |
first-known naturally occurring agonist and antagonist of the muscarinic receptors | muscarine/ACh and atropine |
Nicotinic receptors are _________ (type) channels that ___________ in order to depolarize and excite the neuron. | ligand-gated ion channels; increase permeability of Na+ and Ca++ |
# of molecules of ACh needed to open channel | 2 (two) |
3 most notable places where nicotinic receptors are located | all skeletal muscle neuroeffector junctions, all autonomic ganglion synapses and chromaffin cells of the adrenal medulla |
this subtype of muscarinic cholinergic receptor is typically found at pre-synapse to feedback inhibit | M2, predominate in heart |
M1/3/5 intracellular effects | PLC-beta increased activity, more Ca++ release and smooth muscle contraction/secretion |
M2/4 intracellular effects | inhibit adenylyl cyclase and Ca++ channels, activate K+ channels |
ratio of epi:norepi produced by adrenal medulla | 20 epi:80 norepi |
rate-limiting rxn in NE/epi synthesis | tyrosine --> DOPA via tyrosine hydroxylase |
2 most common ways norepi is removed from synapse | 70% recycling by reuptake and diffusion away from site of action |
2 enzymes that metabolize catecholamines (not associated with removal from synaptic cleft) | monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) |
all adrenergic receptors are of the ______ type | GPCR |
alpha-1 adrenergic receptors are coupled to ___ | Gq, PLC and increased Ca++ |
alpha-2 adrenergic receptors are coupled to ____ | Gi/o and inhibit |
important role of alpha-2 receptors on presynaptic adrenergic nerve terminals | mediate feedback inhibition of NE release |
beta-1/2 adrenergic receptors are coupled to ____ | both to Gs, increased Ca++ |
inhibitor of tyrosine hydroxylase | metyrosine |
old HTN drug that prevents storage of NE | reserpine |
2 substances that block serotonin, NE and dopamine uptake in CNS & PNS | cocaine and TCAs |
Why not use muscarinic antagonists? | there are no non-specific M antagonists, lots of unwanted side effects |
sympathetic always has constant global basal tone whereas para is organized for discrete and local discharge during periods of minimal activity |