Muscle Physiology- Pt 4 Quiz
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Questions and Answers

What is the energy configuration of the myosin head when it is bound to ATP?

  • Low energy configuration (correct)
  • Variable energy configuration
  • High energy configuration
  • Neutral energy configuration
  • What is the result of calcium binding to troponin?

  • The actin binding site is closed
  • The myosin head is in a low energy configuration
  • The actin binding site is opened (correct)
  • The myosin head is in a high energy configuration
  • What is the role of SERCA1a in excitation-contraction coupling?

  • To transmit nerve impulses to the muscle fiber
  • To release calcium ions from the sarcoplasmic reticulum
  • To generate muscle contraction
  • To pump calcium ions back into the sarcoplasmic reticulum (correct)
  • What is the outcome of the myosin head cleaving ATP into ADP + P?

    <p>The myosin head is in a high energy configuration</p> Signup and view all the answers

    Which term correctly describes the overall process which transforms a nerve impulse into a muscle contraction?

    <p>Excitation-contraction coupling</p> Signup and view all the answers

    What happens to ADP after the power stroke?

    <p>ADP detaches from the myosin head</p> Signup and view all the answers

    What is the term for when the myosin head moves from a high energy state to a low energy state, causing actin to be pulled closer to the M-line?

    <p>Power stroke</p> Signup and view all the answers

    What is the term for when the myosin heads bend towards the center of the sarcomere?

    <p>Micro-contraction</p> Signup and view all the answers

    What is the primary function of RyRs in excitation-contraction coupling?

    <p>To release calcium ions from the sarcoplasmic reticulum</p> Signup and view all the answers

    What is the role of DHPR in excitation-contraction coupling?

    <p>To sense voltage changes and trigger calcium release</p> Signup and view all the answers

    What is the term for when myosin is still attached to actin?

    <p>Rigor state</p> Signup and view all the answers

    What is the outcome of the action potential causing a conformational change in the DHPR?

    <p>The RyRs calcium channels open</p> Signup and view all the answers

    What is the name of the theory that describes actin-myosin binding for muscle contractions?

    <p>Walk along theory</p> Signup and view all the answers

    Which is the correct order of events, in regards to excitation-contraction coupling?

    <p>AP scatters across sarcolemma, AP travels through T-Tubule, DHPR conformational change, RyRs calcium release, Muscle contraction</p> Signup and view all the answers

    What is the primary function of the sarcoplasmic reticulum?

    <p>To store calcium ions</p> Signup and view all the answers

    Which is the correct order of events, in regards to the "walk along theory"?

    <p>Cross bridge, power stroke, micro-contraction, rigor state</p> Signup and view all the answers

    Study Notes

    Excitation-Contraction Coupling: General Info

    • Excitation-contraction coupling transforms a nerve impulse into a muscle contraction.
    • T-Tubules are associated with the sarcoplasmic reticulum, which stores calcium.
    • The sarcoplasmic reticulum consists of terminal cisternae and longitudinal tubules surrounding myofibrils.
    • DHPR (dihydropyridine receptors) are voltage-sensing proteins mechanically coupled to RyRs (ryanodine receptors).
    • RyRs are calcium channels on the sarcoplasmic reticulum membrane.
    • Muscle contraction continues as long as calcium ion concentration remains high.
    • SERCA1a (sarcoplasmic reticulum calcium ATPase) is a calcium pump continuously active in the sarcoplasmic reticulum walls.

    Excitation-Contraction Coupling: Steps

    • Action potential travels from the motor end plate to the sarcolemma.
    • The action potential depolarizes the T-Tubule and penetrates the cell.
    • DHPR conformational change triggers RyRs calcium channels to open.
    • Calcium rapidly diffuses out of the sarcoplasmic reticulum.
    • Muscle contraction is initiated.
    • SERCA1a removes calcium ions from the myofibrillar fluid after contraction.

    Walk Along Theory (of muscle contractions): General Info

    • Myosin head bound to ATP is in a low energy configuration.
    • Myosin head cleaves ATP into ADP + P, forming a "cocked position" in a high energy configuration.

    Walk Along Theory (of muscle contractions): Steps

    • Myosin head binds to ATP, entering a low energy configuration.
    • Myosin head cleaves ATP, cocking into a high energy configuration.
    • Calcium binds to troponin, opening the actin binding site.
    • Myosin head binds to actin, forming the cross bridge.
    • Cross bridging triggers Myosin to release the phosphate group, leaving ADP attached.
    • Power stroke occurs, moving myosin from high to low energy state, causing actin to pull closer to the M-line (micro-contraction).
    • ADP detaches from myosin, leaving it in a rigor state.
    • ATP binds to the myosin head group.
    • Myosin detaches from actin.

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    Related Documents

    3- Muscle Physiology- Pt 4.docx

    Description

    Learn about the process of transforming nerve impulses into muscle contractions, including the role of T-tubules and sarcoplasmic reticulum in calcium storage.

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