Term
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Definition
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Term
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Definition
| quaternary amine with a low molecular mass serving as a neurotransmitter in CNS and |
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Term
| Examples of cholinergic sites in the CNS? |
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Definition
synapse in the ganglia of the visceral motor systems
- ACh is the CNS is still not fully understood |
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Term
| Where is ACh synthesized? |
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Definition
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Term
| What is the rate limiting factor of ACh synthesis? |
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Definition
| availability of Choline and Aceytl CoA |
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Term
| Where is Choline obtained from? |
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Definition
| Either from plasma or by metabolism of choline-containing compounds, obtained from egg yolk, liver and vegetables in our diets |
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Term
| What is the concentration of Choline in the plasma? |
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Definition
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Term
| How much of Choline is recycled? |
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Definition
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Term
| What is Aceytl CoA synthesized from? |
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Definition
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Term
| Which enzyme catalyzes the synthesis of ACh? |
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Definition
Choline acetyltransferase (ChAT).
- This enzyme is synthesized in the soma and found in high concentration at the nerve terminal |
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Term
| What stops overproduction of ACh? |
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Definition
| ChAt enzyme is subject to feedback production inhibition where ACh bind to the allosteric site signalling it to stop overproduction of ACh. |
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Term
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Definition
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Term
| What transports the ACh into the vesicles? |
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Definition
| transport protein called Vesicular Acetylcholine transporter (VAChT) |
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Term
| How many molecules of ACh does VAChT stock up into vesicles? |
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Definition
| 10,000 molecules of ACh in cholinergic vesicles. |
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Term
| What mechanism does Vesicular Acetylcholine transporter (VAChT) use? |
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Definition
This pump is driven by a proton pumping ATPase.
(1 H+ out in exhange of 1 NT in driven by hydrolysis of ATP) |
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Term
| Is ACh subject for reuptake? |
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Definition
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Term
| What inactivates ACh in the nerve terminal ? |
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Definition
| Hydrolytic enzyme Acetylcholinesterase |
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Term
| What does Hydrolytic enzyme Acetylcholinesterase do? |
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Definition
| Hydrolyses ACh into acetate and choline |
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Term
| What is the speed of catalytic activity for AChE? |
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Definition
| 5000 molecules of ACh per AChE molecule per second |
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Term
| How is choline reuptaken by neurons? |
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Definition
| via the Choline Transporter |
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Term
| How does the Choline transporter work? |
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Definition
| 1 Choline in - exchange of 1 Na out |
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Term
| Which receptors does ACh bind to? |
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Definition
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Term
| What are the two types of nicotinic AChR |
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Definition
- neuromuscular nAChR
- neuronal nAChR |
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Term
| What is the difference between neuromuscular nAChR and neuronal nAChR? |
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Definition
They both contain 5 sub units but
neuromuscular nAChR contains 2α : 1ß : 1δ : 1ε
neuronal nAChR contains 3α: 2ß |
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Term
| Which sub-unit contains the binding site for ACh? |
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Definition
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Term
| Which ACh receptor is more common in the brain? |
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Definition
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Term
| Describe the structure of mAChR |
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Definition
- 7 helical membrane span proteins
- ACh binding site available on the extracellular surface |
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Term
| What are the 5 subtypes and which G- proteins are they coupled to? |
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Definition
M1 - Gq
M2 - Gi
M3 - Gq
M4 - Gi
M5 - Gq |
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Term
| Where is mAChR highly expressed? |
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Definition
| Striatum and other forebrain regions |
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Term
What effect do they have in the striatum?
(Think Samits lecture) |
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Definition
| Activate inward rectifying K+ channels and Ca activated K+ channels --> results in inhibitory influence on dopamine mediated motor effects |
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Term
| How does Botulinum affect cholinergic transmission? |
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Definition
| Blocks release of ACh; causes muscular paralysis |
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Term
| How does Vesamicol affect cholinergic transmission? |
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Definition
| blocks vesicular ACh transporter - unable to pack ACh into vesicles therefore less available in stores at the terminal - reducing ACh release |
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Term
| How does Hemicolinium affect cholinergic transmission? |
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Definition
| decrease synthesis of ACh by decreasing reuptake of Choline by binding to the Choline transporter |
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Term
| How can cholinergic neurons be located? |
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Definition
| By staining markers of cholinergic neurons including ChaT and AChE |
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Term
| Why is AChE an unreliable marker? |
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Definition
| Enyzme is not present in the neuron but is densly concentrated in the synpatic cleft |
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Term
| Why is ChAT a reliable marker ? |
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Definition
| Selectively lables cholinergic neurons |
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