Podcast
Questions and Answers
What is the role of ATP in the release of actin during muscle contraction?
What is the role of ATP in the release of actin during muscle contraction?
- ATP prevents rigor mortis by continuously binding to actin.
- ATP hydrolysis is necessary for the myosin head to release actin. (correct)
- ATP is produced by muscle cells during contraction to facilitate binding.
- ATP binds to myosin, allowing it to form stronger bonds with actin.
Which statement accurately reflects the behavior of the SERCA pump?
Which statement accurately reflects the behavior of the SERCA pump?
- It is activated by increased calcium levels in the muscle fibers.
- It releases calcium ions into the cytoplasm during contraction.
- It is responsible for calcium uptake into the sarcoplasmic reticulum. (correct)
- It phosphorylates ATP to generate energy for muscle contraction.
What is rigor mortis primarily caused by?
What is rigor mortis primarily caused by?
- Accumulation of ATP in muscle fibers.
- Binding of actin and myosin in the absence of ATP. (correct)
- Continuous electrical stimulation of muscle fibers.
- A lack of calcium ions in the muscle tissue.
What contributes to maintaining the resting membrane potential in muscle cells?
What contributes to maintaining the resting membrane potential in muscle cells?
What initiates the production of muscle action potential?
What initiates the production of muscle action potential?
What initiates the exposure of active sites on actin during muscle contraction?
What initiates the exposure of active sites on actin during muscle contraction?
During the cross bridge cycle, what happens during the power stroke?
During the cross bridge cycle, what happens during the power stroke?
What is the role of acetylcholinesterase in muscle contraction?
What is the role of acetylcholinesterase in muscle contraction?
What occurs when myosin heads bind to the active sites on actin?
What occurs when myosin heads bind to the active sites on actin?
In which part of the muscle fiber is the motor end plate typically found?
In which part of the muscle fiber is the motor end plate typically found?
What happens to calcium ions during the resting state of a muscle?
What happens to calcium ions during the resting state of a muscle?
What is the function of myosin ATPase in muscle contraction?
What is the function of myosin ATPase in muscle contraction?
How does the motor neuron communicate with muscle fibers?
How does the motor neuron communicate with muscle fibers?
What is the significance of the M-line during muscle contraction?
What is the significance of the M-line during muscle contraction?
What does excitation-contraction coupling refer to?
What does excitation-contraction coupling refer to?
What process occurs at the neuromuscular junction to initiate muscle contraction?
What process occurs at the neuromuscular junction to initiate muscle contraction?
What is the role of the sodium-potassium ATPase in muscle physiology?
What is the role of the sodium-potassium ATPase in muscle physiology?
In the sliding filament theory, which zone or band disappears during maximal contraction?
In the sliding filament theory, which zone or band disappears during maximal contraction?
Which part of the muscle fiber is associated with the synaptic end bulb?
Which part of the muscle fiber is associated with the synaptic end bulb?
What is the function of calcium ATPase in muscle relaxation?
What is the function of calcium ATPase in muscle relaxation?
What describes the asynchronous nature of cross-bridge cycling in muscle contraction?
What describes the asynchronous nature of cross-bridge cycling in muscle contraction?
What is the effect of action potential reaching the threshold at the motor end plate?
What is the effect of action potential reaching the threshold at the motor end plate?
Flashcards
Rigor Mortis
Rigor Mortis
The state of muscle stiffness after death, caused by the lack of ATP preventing myosin heads from detaching from actin.
Troponin
Troponin
The protein that binds to calcium, triggering a conformational change in tropomyosin to expose actin-binding sites for myosin.
Tropomyosin
Tropomyosin
The protein that blocks myosin binding sites on actin in a relaxed muscle, moved aside by troponin when calcium is present.
ATP (Adenosine Triphosphate)
ATP (Adenosine Triphosphate)
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SERCA Pump
SERCA Pump
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Sliding Filament Theory
Sliding Filament Theory
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Neuromuscular Junction (NMJ)
Neuromuscular Junction (NMJ)
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Acetylcholine Release
Acetylcholine Release
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Motor End Plate
Motor End Plate
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Cross Bridge Cycle
Cross Bridge Cycle
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Maximal Contraction
Maximal Contraction
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Sodium Potassium ATPase
Sodium Potassium ATPase
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Cross Bridge
Cross Bridge
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Myosin Preparation
Myosin Preparation
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Myosin ATPase
Myosin ATPase
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SR Calcium Release
SR Calcium Release
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Excitation-Contraction Coupling
Excitation-Contraction Coupling
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Motor Unit
Motor Unit
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Acetylcholinesterase
Acetylcholinesterase
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Study Notes
Muscle Physiology
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Sliding Filament Theory: Actin and myosin filaments slide past each other, shortening the muscle. Overlap of filaments changes, but filament lengths themselves do not change.
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Neuromuscular Junction (NMJ): Connection between nervous system and muscle. Axon collateral of somatic motor neuron branches into synaptic end bulbs. Acetylcholine (ACh) is released from synaptic vesicles, triggering an action potential.
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ATP Requirements: Sodium potassium ATPase re-establishes resting membrane potential. Myosin ATPase detaches and stores energy for power strokes. Sarcoendoplasmic reticulum calcium ATPase allows relaxation.
Cross Bridge Cycle
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Cycle Process: Myosin binds to actin, moves it, and releases. Binding is part of preparation, where myosin heads (activated) store energy in upright position.
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Hydrolysis: Myosin ATPase hydrolyzes ATP to ADP + P, storing energy in the heads.
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Binding: Calcium binds to troponin, shifting tropomyosin, exposing active sites. Myosin binds to actin.
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Power Stroke: Energy from myosin heads moves actin toward the M-line (center of sarcomere). ADP is released.
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Release: ATP binds to myosin, causing it to release actin.
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Re-Energization: ATP is hydrolyzed, re-energizing the myosin head, which returns to the starting position.
Electrical Properties
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Resting Membrane Potential: Approximately -85 mV.
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Potassium Leak Channels: More numerous than sodium channels, contributing to resting potential.
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Sodium-Potassium Pump: Requires ATP, maintaining high extracellular sodium and high intracellular potassium. This pump maintains the concentration gradient between sodium and potassium.
Excitation-Contraction Coupling
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Transformation: Action potential (MAP) transforms into muscle contraction.
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Resting State: Calcium channels are closed, troponin is relaxed, and tropomyosin covers active sites.
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Contraction: Action potential triggers calcium release from the sarcoplasmic reticulum, causing calcium binding to troponin. This moves tropomyosin, exposing binding sites on actin. Myosin then binds to actin, initiating the cross-bridge cycle.
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Calcium Uptake: Calcium is taken back up into sarcoplasmic reticulum.
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