Summation of muscle twitches:
W. is due to the addition of the forces produced in response to individual APs.
X. can be caused by the summation of action potentials in the sarcolemma, leading to
stronger contractions.
Y. may lead to the development of a tetanic contaction.
Z. is the only means by which the force of muscular contraction can be increased.
A. if only W, X, and Y are correct
B. if only W, and Y are correct
C. if only X, and Z are correct
D. if only Z is correct
E. if all are correct
