Mer Scott
Test por , creado hace más de 1 año

• Understand why we need muscle (cardiac, smooth, skeletal). • Know the structure and molecular components of skeletal muscle and their interaction. • Know the structure and molecular components of motor unit (neuromuscular junction). • Understand the mechanism of contraction

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Mer Scott
Creado por Mer Scott hace alrededor de 7 años
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L25 Skeletal Muscle Structure and Function

Pregunta 1 de 12

1

Skeletal muscle is essential for movement, posture, and heat generation.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 2 de 12

1

A muscle cell is made of myofilaments, and the sarcomeres within it are made of myofibrils.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 3 de 12

1

Myofibrils have around 30,000 sarcomeres.

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  • FALSO

Explicación

Pregunta 4 de 12

1

Selecciona la opción correcta de los menús desplegables para completar el texto.

( Sarcoplasmic Reticulum, T-tubule(Transverse tubule), Triad ): The ER of the muscle. Stores calcium.
( T-tubule(Transverse tubule), Triad, Sarcoplasmic Reticulum ): invaginated sarcolemma, enhances calcium transport.
( Triad, Sarcoplasmic Reticulum, T-tubule(Transverse tubule) ): T-tubule in between two SR.

Explicación

Pregunta 5 de 12

1

Troponin and tropomyosin attach to myosin, making them part of the thick filament.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 6 de 12

1

If a motor neuron innervates a large number of muscle fibres, the action is precise.
If a motor neuron innervates a small number of muscle fibres, the action is unprecise.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 7 de 12

1

Choose the correct statements.

Selecciona una o más de las siguientes respuestas posibles:

  • A muscle fibre is innervated by multiple motor neurons.

  • A motor neuron always innervates only one muscle fibre.

  • The more muscle fibres innervated by a neuron, the more precise the movement.

  • None of these are correct.

Explicación

Pregunta 8 de 12

1

The mechanism of contraction of skeletal muscles begins with . Here, the action potential is transferred to a action potential via the neurotransmitter ACh. (This ACh is diffused through the NMJ when channels opening in the neuron trigger the release of vesicles.)
Next, occurs. ACh receptors open voltage gated channels, which depolarises the muscle membrane (). Ca++ is released from the and diffuses into the firstly the , and then the . Here it forms crossbridges with the myofilaments, allowing them to interdigiate.
After, the muscle when Ca++ is taken up into the SR and the crossbridges .

Arrastra y suelta para completar el texto.

    excitation
    neuronal
    muscular
    Ca++
    contraction
    Na+
    sarcolemma and T-tubules
    SR
    sarcoplasm
    myofilaments
    relaxes
    uncouple

Explicación

Pregunta 9 de 12

1

Choose the incorrect statement.

Selecciona una de las siguientes respuestas posibles:

  • When Ca++ binds to the troponin-tropomyosin complex, it changes its composition, to open the binding site for myosin.

  • Myosin is in an energised state before Ca++ enters.

  • ATP is released when the myosin moves in its power stroke.

  • Myosin binding to the open site on actin is the formation of the crossbridge.

Explicación

Pregunta 10 de 12

1

The sarcolemma depolarises when no new AP innervates it.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 11 de 12

1

Ca++ ions diffuse back into the SR when the muscle relaxes, and can no longer bind to troponin.

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  • VERDADERO
  • FALSO

Explicación

Pregunta 12 de 12

1

When Ca++ leaves the myofilaments, they uncouple passively.

Selecciona uno de los siguientes:

  • VERDADERO
  • FALSO

Explicación

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