Podcast
Questions and Answers
What molecule binds to the myosin cross-bridge head to initiate the process?
What molecule binds to the myosin cross-bridge head to initiate the process?
- Actin
- ATP (correct)
- ADP
- Calcium
Which neurotransmitter is released at the neuromuscular junction to initiate muscle contraction?
Which neurotransmitter is released at the neuromuscular junction to initiate muscle contraction?
- Acetylcholine (correct)
- Serotonin
- Dopamine
- Epinephrine
What structure does the action potential travel down to reach the sarcoplasmic reticulum?
What structure does the action potential travel down to reach the sarcoplasmic reticulum?
- Myofibril
- Sarcomere
- Actin Filament
- T-tubules (correct)
Which ion is released from the sarcoplasmic reticulum (SR) to trigger muscle contraction?
Which ion is released from the sarcoplasmic reticulum (SR) to trigger muscle contraction?
What protein does calcium bind to on actin to expose myosin binding sites?
What protein does calcium bind to on actin to expose myosin binding sites?
The binding of myosin heads to actin forms what structure?
The binding of myosin heads to actin forms what structure?
What causes the myosin heads to swivel, pulling actin and Z-lines towards the cell center?
What causes the myosin heads to swivel, pulling actin and Z-lines towards the cell center?
During muscle contraction, what happens to the sarcomere?
During muscle contraction, what happens to the sarcomere?
What structure pulls actin filaments towards the center of the sarcomere?
What structure pulls actin filaments towards the center of the sarcomere?
After ATP splits into ADP and P, what does the energy released do to the cross-bridges?
After ATP splits into ADP and P, what does the energy released do to the cross-bridges?
Flashcards
ATP Hydrolysis in Muscle Contraction
ATP Hydrolysis in Muscle Contraction
ATP binds to myosin, which is then split into ADP and P, releasing energy. This energy moves the cross-bridges into a high affinity position.
Neuromuscular Junction Action
Neuromuscular Junction Action
A motor neuron releases acetylcholine at the neuromuscular junction, triggering an action potential on the sarcolemma.
Action Potential Propagation
Action Potential Propagation
The action potential spreads through the sarcolemma and T-tubules.
Calcium Release
Calcium Release
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Calcium's Role in Exposing Binding Sites
Calcium's Role in Exposing Binding Sites
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Cross-Bridge Formation and Power Stroke
Cross-Bridge Formation and Power Stroke
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Study Notes
- ATP binds to myosin cross-bridge head, splitting ATP into ADP and P, releasing energy.
- The released energy swivels the cross-bridges to a "high affinity" position.
- A motor neuron releases acetylcholine at the neuromuscular junction.
- Acetylcholine binds to receptors on the motor end plate of the sarcolemma, causing an action potential.
- The action potential spreads through the sarcolemma and down the T-tubules.
- Sarcoplasmic reticulum (SR) channels open and release calcium ions (Ca2+).
- Calcium ions bind to protein on actin, exposing binding sites for myosin heads.
- Myosin heads attach to actin, forming cross-bridges.
- Myosin heads release P and ADP, causing the heads to swivel, pulling actin and Z-lines towards the cell center, shortening the sarcomere.
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