Which of the following statements regarding contraction of a skeletal muscle fiber is TRUE?
A. Some contractions occur without cross-bridge activation.
B. Contracting muscle fibers do not always shorten.
C. Contraction only occurs following summation of action potentials from many motor neurons.
D. Contraction does not always require the occurrence of an action potential.
E. Thick filaments shorten when muscle cells contract.
Answer: B
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a) Mucous membrane b) Serous membrane c) Cutaneous membrane d) Synovial membrane
The ________ principle states that the properties of the action potential are independent of the relative strength of the depolarizing stimulus.
Fill in the blank(s) with the appropriate word(s).
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a. diaphragm relaxes. b. external intercostal muscles relax. c. internal intercostals muscles relax. d. two of these. e. all of these.
Situs inversus is a condition in which __________.
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