1. Rank the sequence of events at the NMJ that initiate an action potential in t
ID: 3513191 • Letter: 1
Question
1. Rank the sequence of events at the NMJ that initiate an action potential in the muscle fiber, from first to last.
- Action potential arrives at the axon terminal.
- Acetylcholine binds to its receptors on the junctional folds.
- Calcium ions enter the axon terminal.
- Synaptic vesicles fuse to membrane of axon terminal.
- Junctional folds become depolarized.
- Action potential is initiated on the sarcolemma.
- Acetylcholine is released into the synaptic cleft.
2. Match term to the appropriate definition.
Terms:
- Acetylcholine
- Synaptic vesicle
- Acetylcholinesterase
- Sodium channel
- Acetylcholine receptor
- Calcium channel
- Synaptic cleft
Definitions:
- Neurotransmitter that stimulates skeletal muscle contraction.
- Membranous sac located in the axon terminal that contains neurotransmitter.
- Enzyme located in the synaptic cleft that breaks down acetylcholine.
- A type of voltage-gated ion channel located on the axon terminal.
- The space between the axon terminal and junctional folds.
- A type of voltage-gated ion channel located on the sarcolemma of the muscle fiber.
- A type of chemically-gated ion channel located on the junctional folds of the muscle fiber.
Explanation / Answer
1. Action potential arrives at the axon terminal --->Calcium ions enter the axon terminal ---> Synaptic vesicles fuse to membrane of axon terminal --->Acetylcholine is released into the synaptic cleft ----> Acetylcholine binds to its receptors on the junctional folds ---> Junctional folds become depolarized ---> Action potential is initiated on the sarcolemma.
2. Acetylcholine - Neurotransmitter that stimulates skeletal muscle contraction.
Synaptic vesicle - Membranous sac located in the axon terminal that contains neurotransmitter.
Acetylcholinesterase - Enzyme located in the synaptic cleft that breaks down acetylcholine.
Calcium channel - A type of chemically-gated ion channel located on the junctional folds of the muscle fiber.
Sodium channel - A type of voltage-gated ion channel located on the sarcolemma of the muscle fiber.
Synaptic cleft - The space between the axon terminal and junctional folds.
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