Podcast
Questions and Answers
Once the muscle cell has been excited it will ______________.
Once the muscle cell has been excited it will ______________.
contract
A muscle action potential will trigger a release of __________ into the sarcoplasm.
A muscle action potential will trigger a release of __________ into the sarcoplasm.
ca2+
What do the calcium ions bond?
What do the calcium ions bond?
The calcium ions bond to regulatory proteins and trigger a contraction.
A single nervous signal releases calcium ions in the ____________ to initiate the contraction cycle.
A single nervous signal releases calcium ions in the ____________ to initiate the contraction cycle.
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List the 4 steps of the contraction cycle.
List the 4 steps of the contraction cycle.
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What happens during Step 1: ATP Hydrolysis?
What happens during Step 1: ATP Hydrolysis?
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What occurs during Step 2: Cross Bridge Attachment?
What occurs during Step 2: Cross Bridge Attachment?
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Describe Step 3: Power Stroke.
Describe Step 3: Power Stroke.
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What happens during Step 4: Cross Bridge Detachment?
What happens during Step 4: Cross Bridge Detachment?
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The contraction cycle will repeat so long as ______________.
The contraction cycle will repeat so long as ______________.
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The contraction will continue so long as ______________.
The contraction will continue so long as ______________.
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What happens during maximum muscle contraction?
What happens during maximum muscle contraction?
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Study Notes
Muscle Contraction Cycle Overview
- Muscle contraction initiates once the muscle cell is excited and ready to contract.
- A muscle action potential triggers the release of calcium ions (Ca2+) into the sarcoplasm, essential for contraction.
Role of Calcium Ions
- Calcium ions bind to regulatory proteins in muscle fibers, initiating the contraction process.
- Calcium release occurs in the sarcoplasm as a response to a single nervous signal, acting as a trigger for the contraction cycle.
Contraction Cycle Steps
- The contraction cycle consists of four key steps:
- ATP Hydrolysis
- Cross Bridge Attachment
- Power Stroke
- Cross Bridge Detachment
Step 1: ATP Hydrolysis
- ATP (adenosine triphosphate) energizes myosin molecules, enabling them to perform power strokes necessary for contraction.
Step 2: Cross Bridge Attachment
- Myosin heads temporarily attach to actin filaments, forming cross bridges essential for muscle contraction.
Step 3: Power Stroke
- Myosin filaments pull the actin filaments during the power stroke after phosphate is released, sliding the filaments and causing contraction. ADP is also released during this phase.
Step 4: Cross Bridge Detachment
- The binding of a new ATP molecule to the myosin cross bridge results in detachment from actin, allowing the cycle to repeat.
Contraction Cycle Continuity
- The contraction cycle continues as long as myosin ATPase can hydrolyze newly attached ATP molecules.
Conditions for Continued Contraction
- Sustained contraction is dependent on the availability of ATP and high calcium ion levels near thin filaments.
Maximum Contraction
- During maximum muscle contraction, the distance between Z discs can reduce to half their resting length, indicating a fully contracted state.
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Description
Test your knowledge on the muscle contraction cycle with these flashcards. Each card covers key concepts such as muscle cell excitation, calcium ion release, and regulatory proteins that trigger contractions. Perfect for students studying muscle physiology!
