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Questions and Answers
What is the initial neurotransmitter released at the neuromuscular junction?
What is the initial neurotransmitter released at the neuromuscular junction?
Where does the depolarization of the muscle cell membrane occur?
Where does the depolarization of the muscle cell membrane occur?
What structure spreads the action potential into the muscle fiber?
What structure spreads the action potential into the muscle fiber?
What stimulates the release of calcium ions from the sarcoplasmic reticulum?
What stimulates the release of calcium ions from the sarcoplasmic reticulum?
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Which protein binds to calcium ions in muscle cells?
Which protein binds to calcium ions in muscle cells?
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What causes a conformational change in the troponin-tropomyosin complex?
What causes a conformational change in the troponin-tropomyosin complex?
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What provides energy for myosin heads during cross-bridge formation?
What provides energy for myosin heads during cross-bridge formation?
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Where are the binding sites on actin exposed during muscle contraction?
Where are the binding sites on actin exposed during muscle contraction?
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Which structure releases stored calcium ions into the cytoplasm of the muscle cell?
Which structure releases stored calcium ions into the cytoplasm of the muscle cell?
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What is responsible for pulling actin filaments toward the center of the sarcomere?
What is responsible for pulling actin filaments toward the center of the sarcomere?
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Which neurotransmitter binds to receptors on the muscle cell membrane at NMJ?
Which neurotransmitter binds to receptors on the muscle cell membrane at NMJ?
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What is responsible for generating an action potential that spreads along the sarcolemma and into the muscle fiber?
What is responsible for generating an action potential that spreads along the sarcolemma and into the muscle fiber?
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Study Notes
Neuromuscular Junction
- The initial neurotransmitter released at the neuromuscular junction is acetylcholine.
Muscle Cell Membrane
- Depolarization of the muscle cell membrane occurs at the motor end plate.
Muscle Fiber
- The T-tubules (transverse tubules) spread the action potential into the muscle fiber.
Sarcoplasmic Reticulum
- The depolarization of the T-tubules stimulates the release of calcium ions from the sarcoplasmic reticulum.
Calcium Ions
- Calcium ions bind to the troponin protein in muscle cells.
Muscle Contraction
- The binding of calcium ions to troponin causes a conformational change in the troponin-tropomyosin complex, which exposes the binding sites on actin.
Cross-Bridge Formation
- ATP provides energy for myosin heads during cross-bridge formation.
Muscle Contraction Process
- Myosin heads are responsible for pulling actin filaments toward the center of the sarcomere.
Sarcoplasmic Reticulum Function
- The sarcoplasmic reticulum releases stored calcium ions into the cytoplasm of the muscle cell.
Neuromuscular Junction Communication
- Acetylcholine binds to receptors on the muscle cell membrane at the neuromuscular junction.
Action Potential Generation
- The binding of acetylcholine to its receptors is responsible for generating an action potential that spreads along the sarcolemma and into the muscle fiber.
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Description
Learn about the molecular and electrical processes involved in muscle cell excitation–contraction coupling at the neuromuscular junction. Understand the role of acetylcholine release, action potential propagation, and sarcolemma depolarization.
