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3 Cards in this Set
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Adrenergic Neurotransmitters Acetylcholine Neurotransmitter at both nicotinic and muscarinic receptors It's preganglionic and motor for direct transmission from CNS Norepinephrine Dopamine Epinephrine Synthesis of acetylcholine Choline is accumulated in cholinergic presynaptic nerve endings via Na+ pump active transport Choline+Acetyl COA in presynaptic terminal to form ACh Enzyme is choline Acetyl transferase Depolarization at presynaptic membrane open voltage gated Ca+ channel , influx of Ca+ cause fusion of synaptic vesicles membrane with presynaptic membrane causing exocytosis of ACh Inactivated by acetylcholine esterase at post junctional Choline uptake is inhibited by hemicholinium Botulinum toxin prevent release of ACh from synaptic vesicles by binding synaptobrevin |
Norepinephrine Synthesis Tyrosine actively transported into nerve endings; converted to L DOPA via tyrosine hydroxylase; rate limiting step; DOPA converted to dopamine via L aromatic amino acids decarboxylase: dopamine taken up into storage vesicles where it's metabolized to norepinephrine via Dopamine Beta hydroxylase; Release Presynaptic membrane depolarization open Ca+ gated voltage channels; influx of Ca causes fusion of presynaptic membrane and synaptic membrane; exocytosis of norepinephrine into neuroeffector junction Metabolism Termination of its action is removal from neuroeffector junction back to synaptic terminal via norepinephrine reuptake transport system. Metabolism is by catechol-O-methyltransferase(COMT) in synapse or MAO in prejunctional nerve terminal |
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Epinephrine |
Norepinephrine |
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Dopamine |
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