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Flashcards in MR S10 - Incomplete Deck (6)
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Describe the storage of ACh

Actively packaged into high concentration (>100mM) vesicles at cholinergic terminals


Describe the termination of ACh

Acetylcholine esterase degrades ACh to choline and acetate
In fast/nicotinic synapses, the enzyme is faster so half life of ACh is only a few milliseconds
A choline channel on the terminal of the synapse recaptures most choline


Describe the synthesis of noradrenaline

Tyrosine is converted to DOPA by tyrosine hydroxylase (which is the rate-limiting step)
DOPA is converted to dopamine by aromatic amino acid decarboxylase (which is then packaged in a vesicle)
Dopamine is converted to noradrenaline by dopamine β hydroxylase (this occurs within the vesicle)


Describe the packaging of noradrenaline

Active transport required to package dopamine into a vesicle, where it is converted to NA
High-concentration vesicle (0.5-1.0M)


Describe the termination of noradrenaline

Uptake 1 is a high affinity reuptake system which removes NA from the synaptic cleft into cells
Uptake 2 is a widespread, lower affinity reuptake system which removes NA from the extracellular space
Cytoplasmic NA may be broken down by mono amine oxidase (MOA)


Describe the synthesis of ACh

ACh is synthesised from acetyl CoA and choline by the enzyme choline acetyltransferase in the cytoplasm of cholinergic terminals