2022-05-15T17:13:25+03:00[Europe/Moscow] en true <p>what are the thick filaments within a myofibril made up of</p>, <p>what are myosin molecules</p>, <p>what is the function of the fibrous part of the myosin molecule</p>, <p>how are the myosin molecules arranged in the thick filament</p>, <p>what are the thin filaments within a myofibril made up of</p>, <p>what are actin molecules</p>, <p>many actin molecules link together to form </p>, <p>how many chains form one thin filament</p>, <p>what other fibrous protein is twisted around the two chains of actin molecules</p>, <p>what other protein is attached to the actin chains and in what way</p>, <p>how do muscles cause movement </p>, <p>what action happens during a muscle contraction</p>, <p>what is the sliding filament model of muscle contraction </p>, <p>sliding filament model of muscle contraction process (1)</p>, <p>sliding filament model of muscle contraction process (2)</p>, <p>sliding filament model of muscle contraction process (3)</p>, <p>sliding filament model of muscle contraction process (4)</p>, <p>sliding filament model of muscle contraction process (5)</p>, <p>sliding filament model of muscle contraction process (6)</p>, <p>sliding filament model of muscle contraction process (7)</p>, <p>sliding filament model of muscle contraction process (8)</p>, <p>sliding filament model of muscle contraction process (9)</p>, <p>sliding filament model of muscle contraction process (10)</p>, <p>what are the requirements for full contraction of a muscle</p> flashcards

A2 Sliding Filament Model of Muscular Contraction

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  • what are the thick filaments within a myofibril made up of

    myosin molecules

  • what are myosin molecules

    these are fibrous protein molecules with a globular head

  • what is the function of the fibrous part of the myosin molecule

    it anchors the molecule into the thick filament

  • how are the myosin molecules arranged in the thick filament

    lie next to each other with their globular heads all pointing away from the M line

  • what are the thin filaments within a myofibril made up of

    actin molecules

  • what are actin molecules

    these are globular protein molecules

  • many actin molecules link together to form

    a chain

  • how many chains form one thin filament

    two actin chains twisted together

  • what other fibrous protein is twisted around the two chains of actin molecules

    tropomyosin

  • what other protein is attached to the actin chains and in what way

    troponin at regular intervals

  • how do muscles cause movement

    by contracting

  • what action happens during a muscle contraction

    sarcomeres within myofibrils shorten as the Z discs are pulled closer together

  • what is the sliding filament model of muscle contraction

    when sarcomeres within myofibrils shorten as Z discs are pulled closer together

  • sliding filament model of muscle contraction process (1)

    an action potential arrives at the neuromuscular junction

  • sliding filament model of muscle contraction process (2)

    calcium ions are released from the sarcoplasmic reticulum (SR)

  • sliding filament model of muscle contraction process (3)

    calcium ions bind to troponin molecules stimulating them to change shape

  • sliding filament model of muscle contraction process (4)

    causes troponin and tropomyosin proteins to change position on the actin (thin) filaments exposing the myosin binding sites on the actin molecules

  • sliding filament model of muscle contraction process (5)

    globular heads of the myosin molecules bind with these sites forming cross bridges between the two types of filament

  • sliding filament model of muscle contraction process (6)

    myosin heads move and pull the actin filaments towards the center of the sarcomere causing the muscle to contract a very small distance

  • sliding filament model of muscle contraction process (7)

    ATP hydrolysis occurs at the myosin heads providing the energy required for the myosin heads to release the actin filaments

  • sliding filament model of muscle contraction process (8)

    myosin heads move back to their original positions and bind to new binding sites o the actin filaments closer to the Z disc

  • sliding filament model of muscle contraction process (9)

    myosin heads move again pulling the actin filaments even closer to the center of the sarcomere causing the sarcomere to shorten once more and pulling the Z discs closer together

  • sliding filament model of muscle contraction process (10)

    the myosin heads hydrolyse ATP once more in order to detach again

  • what are the requirements for full contraction of a muscle

    troponin and tropomyosin are not blocking the myosin-binding sites and the muscle has a supply of ATP