by jheeb


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Binding of the myosin head sequentailly prevents "_____________" of the thin filament. This makes it seem that the myosin is "_______" the actin ______.

  • back-sliding

  • walking

  • forward

Calcium ions are moved back into the SR by the process known as ____________ which is facilitated by specialized _________________. This process requires___.

  • Active transport

  • Calcium Ion Pumps

  • ATP

During muscle contraction, the ________shortens but the __________remains the same.

  • Sarcomere

  • Myofilament

Flexing the myosin head provides what is known as the ________.
power stroke
Hydrolysis of ATP returns the myosin head to its ____________conformation.
high-energy
Name 3 roles of ATP in the contraction of muscle.

  • Energizes power stroke of myosin head

  • Disconnects myosin head from actin

  • Actively transports calcium ions back to the sarcoplasmic reticulum


 
The myosin head contains binding sites for what 2 molecules?

  • Actin

  • ATP

The thick filament is composed of what molecule?
Myosin
True or False.
When a muscle contracts, all crossbridges are synchronized to bind and disconnect at the same time.
False. Not all crossbridges will bind and disconnect at the same time, because is this were done, the thin filament would never be moved forward, contracting the sarcomere. The myosin heads bind at different times to prevent the thin filament backsliding so as to "walk" the filament continually forward.
Waht are the 3 molecules that make up the thin filament?

  • Actin

  • Tropomyosin

  • Troponin

What are the 6 steps of the cross bridge cycling?

  • Influx of calcium ions

  • Binding of myosin to actin

  • Power stroke, causing sliding of thin filaments

  • Binding of ATP to cross bridge

  • Hydrolysis of ATP

  • Transfer of calcium ions back to the SR

What is the name of the condition in which muscles become rigid after death?
Rigor Mortis
What molecule is connected to the z-line?
Actin
What molecule must bind to the myosin head in order for it to disconnect from the actin?
ATP
What triggers the condition of body rigidity posthumously?
No ATP synthesis=ATP depletion=No disconnect of myosn head from actin, keeping muscles in a temporary (several hours) contracted state.
What triggers the release of calcium ions?
Action potential is passed down the T-tubules to the terminal cisternae
Where are calcium ions stored?
Terminal cisternae
Which molecule on the thin filament covers the binding site for myosin heads?
Tropomyosin
Which molecule on the thin filament has a binding site to calcium ions?
Troponin
Which molecule on the thin filament has a minding site for myosin heads?
Actin
Which muscle tissue appears branched and has a loose conformation?
Cardiac
Which muscle tissue appears striated and is voluntary?
Skeletal
Which muscle tissue functions as a posture-holding, gross and fine motor movement muscle?
Skeletal
Which muscle tissue functions to move the blood throughout the whole body via intense contractions?
Cardiac
Which muscle tissue functions to move things internally throughout the body systems?
Smooth
Which muscle tissue is found only in the heart?
Cardiac
Which muscle tissue is only found attached to bones?
Skeletal
Which muscle tissue is striated and is involuntary?
Cardiac
Which muscle tissue lines the organs and blood vessels?
Smooth
Which muscle tissue is involuntary and does not  appear striated?
Smooth
Which of the following shorten during contraction?
     a. thin filament
     b. sarcomere
     c. H zone
     d. thick filament
    

  • b. sarcomere

  • c. H zone

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