Podcast
Questions and Answers
What is the main function of the parasympathetic division of the ANS?
What is the main function of the parasympathetic division of the ANS?
Where is Acetyl-CoA synthesized in neurons?
Where is Acetyl-CoA synthesized in neurons?
What is the rate-limiting step in Acetylcholine (ACh) synthesis?
What is the rate-limiting step in Acetylcholine (ACh) synthesis?
Which enzymes catalyze the synthesis of Acetylcholine (ACh)?
Which enzymes catalyze the synthesis of Acetylcholine (ACh)?
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What is the function of Cholinergic neurons?
What is the function of Cholinergic neurons?
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How is choline transported into neuron terminals?
How is choline transported into neuron terminals?
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What triggers the release of vesicles at the terminal?
What triggers the release of vesicles at the terminal?
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Which proteins interact with Ca2+ ions to destabilize storage vesicles?
Which proteins interact with Ca2+ ions to destabilize storage vesicles?
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Which substances can unpredictably prolong muscle paralysis when used as adjuncts to general anesthesia?
Which substances can unpredictably prolong muscle paralysis when used as adjuncts to general anesthesia?
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How do botulinum toxin and β-bungarotoxin affect the release of ACh from vesicles?
How do botulinum toxin and β-bungarotoxin affect the release of ACh from vesicles?
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What effect does Latrotoxin, found in black widow spider venom, have on synaptic vesicles?
What effect does Latrotoxin, found in black widow spider venom, have on synaptic vesicles?
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Which agents inhibit Ca2+ entry during the release process of vesicles?
Which agents inhibit Ca2+ entry during the release process of vesicles?
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What is the main function of the Sympathetic division of the ANS?
What is the main function of the Sympathetic division of the ANS?
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Which enzyme catalyzes the synthesis of Acetylcholine (ACh) from acetyl-CoA and choline?
Which enzyme catalyzes the synthesis of Acetylcholine (ACh) from acetyl-CoA and choline?
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What is a direct inhibitor of the enzyme Choline acetyltransferase (ChAT)?
What is a direct inhibitor of the enzyme Choline acetyltransferase (ChAT)?
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Which group of drugs can block the carrier that transports choline into neuron terminals?
Which group of drugs can block the carrier that transports choline into neuron terminals?
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Where is Acetyl-CoA synthesized in neurons before being used in Acetylcholine (ACh) synthesis?
Where is Acetyl-CoA synthesized in neurons before being used in Acetylcholine (ACh) synthesis?
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What is the role of the antiporter that transports synthesized ACh into vesicles?
What is the role of the antiporter that transports synthesized ACh into vesicles?
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What is required for the release of Acetylcholine (ACh) from the vesicles into the synaptic cleft?
What is required for the release of Acetylcholine (ACh) from the vesicles into the synaptic cleft?
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Which proteins interact with Ca2+ ions to destabilize the storage vesicles during the release process?
Which proteins interact with Ca2+ ions to destabilize the storage vesicles during the release process?
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How do Mg2+ ions and aminoglycoside antibiotics affect the release of Acetylcholine (ACh) from vesicles?
How do Mg2+ ions and aminoglycoside antibiotics affect the release of Acetylcholine (ACh) from vesicles?
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What is the mechanism through which Botulinum toxin and β-bungarotoxin block the release of Acetylcholine (ACh) from vesicles?
What is the mechanism through which Botulinum toxin and β-bungarotoxin block the release of Acetylcholine (ACh) from vesicles?
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What effect does Latrotoxin from black widow spider venom have on the synaptic vesicles?
What effect does Latrotoxin from black widow spider venom have on the synaptic vesicles?
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What is the impact of agents like streptomycin and neomycin on muscle paralysis when used during general anesthesia?
What is the impact of agents like streptomycin and neomycin on muscle paralysis when used during general anesthesia?
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Study Notes
Autonomic Nervous System (ANS)
- The ANS has two divisions: Sympathetic and Parasympathetic
- The Sympathetic division mobilizes the body during extreme situations
- The Parasympathetic division performs maintenance activities and conserves body energy
- The two divisions counterbalance each other's activity
Cholinergic Transmission Synthesis
- Cholinergic neurons contain large numbers of small membrane-bound vesicles concentrated near the synaptic portion of the cell membrane
- ACh is synthesized in the cytoplasm from acetyl-CoA and choline by the catalytic action of Choline acetyltransferase (ChAT)
- α-ketoacids and naphthoquinones are direct inhibitors of the enzyme ChAT
- Acetyl-CoA is synthesized in mitochondria, which are present in large numbers in the nerve ending
Choline Transport
- Choline is transported from the extracellular fluid into the neuron terminal by a Na+-dependent membrane choline cotransporter (Carrier A)
- This carrier can be blocked by hemicholiniums
- The action of the choline transporter is the rate-limiting step in ACh synthesis
ACh Transport and Release
- Synthesized ACh is transported from the cytoplasm into the vesicles by an antiporter that removes protons (carrier B)
- This transporter can be blocked by vesamicol
- Release of ACh is dependent on extracellular Ca2+ and occurs when an action potential reaches the terminal and triggers sufficient influx of Ca2+ ions
- The increased Ca2+ concentration "destabilizes" the storage vesicles by interacting with special proteins: VAMPs and SNAP
Inhibitors of ACh Release
- Mg2+ and various aminoglycoside antibiotics (e.g. streptomycin and neomycin) can inhibit Ca2+ entry and unpredictably prolong muscle paralysis
- Botulinum toxin and β-bungarotoxin block the ACh vesicle release process through the enzymatic removal of two amino acids from one or more of the fusion proteins
- Latrotoxin, the toxin in black widow spider venom, causes all the ACh stored in synaptic vesicles to empty into the synaptic gap, resulting in muscular spasm
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Description
Test your knowledge on the two divisions of the autonomic nervous system - Sympathetic and Parasympathetic, as well as cholinergic transmission. Learn how these divisions function, their roles in the body, and the process of cholinergic transmission in neurons.
