Which of the following statements regarding contraction of a skeletal muscle fiber is TRUE?
A. Thick filaments shorten when muscle cells contract.
B. Some contractions occur without cross-bridge activation.
C. Contracting muscle fibers do not always shorten.
D. Contraction does not always require the occurrence of an action potential.
E. Contraction only occurs following summation of action potentials from many motor neurons.
C
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Which of the following terms does NOT belong with the others?
A. Medulla oblongata B. Midbrain C. Reticular formation D. Pons E. Thalamus
The term used for a cytokine that is released by one white blood cell that acts on another is ________.
Fill in the blank(s) with the appropriate word(s).
In blood plasma:
a. the number of positive ions is greater than the number of negative ions b. the number of positive ions is less than the number of negative ions c. the number of positive and negative ions are equal d. there are no electrolytes
Which of the following is NOT one of the factors that make the sexuality of blacks somewhat different from that of whites?
A. The African heritage B. The influences of the Judeo-Christian tradition C. The current economic and social conditions D. The gender roles in African-American society epitomized in the concepts of machismo and marianismo