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In fast-twitch oxidative-glycolytic fibers, their rapid increases in force rely on the ________ activity where rapid relaxation requires ________ activity.

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myosin ATP...

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A construction worker entered the emergency room after an accident in which his leg was crushed by falling beams.A color of the urine sample is noticeably reddish brown.Assuming that color is related to the accident, what molecule could have been released from the damaged muscle cells that colored the urine? What is the function of this molecule?

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The molecule is likely to be t...

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The speed with which force is developed by skeletal muscles is determined by the


A) Ca²⁺ ATPase activity.
B) sarcoplasmic calcium concentration.
C) myosin ATPase isoform.
D) Ca²⁺ ATPase activity and sarcoplasmic calcium concentration.
E) Ca²⁺ ATPase activity, myosin ATPase isoform, and sarcoplasmic calcium concentration.

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A(n)________ contraction describes the opening of stretch-activated channels in smooth muscle cells in response to a distortion of the cell membrane that is commonly observed in ________.

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myogenic, ...

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Match the structures with the accurate description. -highly organized bundles of contractile proteins within a skeletal muscle cell


A) muscle fiber
B) fascicle
C) sarcolemma
D) myofibril
E) t-tubules

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The function of transverse tubules is to


A) store Ca²⁺ ions inside the muscle fiber.
B) rapidly conduct action potentials to the interior of the muscle fiber.
C) ensure a supply of glycogen throughout the muscle sarcoplasm.
D) conduct ATP molecules out of the mitochondria throughout the sarcoplasm.

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You and your lab partner use a living nerve and muscle preparation to study muscle contraction.When you stimulate the nerve electrically, the muscle contracts; why? When you turn off the stimulator but add a high concentration of caffeine to the fluid surrounding the tissues, the muscle contracts; why (speculate on possible sites/mechanisms of action)? When curare (which blocks neuromuscular transmission)is added with caffeine, contraction occurs; why (speculate, and how does this alter your previous answer)? Can you identify a single site of action from this information? If not, what additional experiment would narrow your choices?

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The applied electrical current opens vol...

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Explain the events leading up to a skeletal muscle twitch, starting with the arrival of neurotransmitter in the neuromuscular junction.

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See Figure 12.10 in the chapter. Acetylc...

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Smooth muscle cells lack which protein(s) ?


A) actin only
B) myosin only
C) troponin only
D) tropomyosin only
E) troponin and tropomyosin

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Skeletal muscle fibers with the greatest endurance rely on ________ for energy.


A) anaerobic glycolysis
B) oxidative phosphorylation
C) lactic acid accumulation
D) ketone body degradation

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Groups of adjacent fibers bundled together into units are called ________.These bundles are surrounded by the proteins ________ and elastin as well as ________ that deliver nutrients to the muscle cells.

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fascicles,...

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When comparing complete tetanus with unfused (incomplete) tetanus, which is True?


A) Complete tetanus involves some relaxation between twitches.
B) Complete tetanus involves development of maximum tension.
C) Complete tetanus occurs at a lower frequency of stimulation than unfused tetanus.
D) Complete tetanus would occur when there is more time between twitch contractions.

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Motor units that control skeletal muscles involved with fine motor movements (eye muscles or the hands) have ________ muscle fibers than motor units that control more gross movements (gastrocnemius muscle of the lower leg) .


A) more
B) fewer
C) the same number of

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Striated muscles are so-called because of a repeating pattern of light and dark bands.One repeating unit of the banding pattern is called a


A) myofilament.
B) myomere.
C) sarcofibril.
D) sarcomere.
E) crossbridge.

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Match from the following list. -The lightest color bands of the sarcomere, comprised only of thin filaments.


A) A band
B) I band
C) Z disk
D) H zone
E) M line

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The gap junctions in cardiac muscle are part of specialized cell junctions that are localized to the ________.

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In order to contract and relax, muscle cells require energy in the form of ________.The immediate backup energy source is ________ that requires the enzyme ________.

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ATP, phosp...

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In order for the bicep muscle to shorten, the force applied by the muscle must be ________ the load applied at the hand.


A) greater than
B) less than
C) equal to

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Factors playing a role in fatigue can be classified into two categories.Define those two categories and provide an example of each.

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Central fatigue, peripheral fatigue.Cent...

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Briefly compare and contrast the structure and behavior of cardiac, smooth, and skeletal muscles.

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See Table ...

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