Passage I

A muscle twitch (a stimulus-contraction-relaxation cycle) is divided into 3 phases (the latent period, the contraction phase, and the relaxation phase) based on the timing of the stimulus and changes in the force generated by the muscle. Table 1 shows when each phase starts and ends.

Figure 1 shows the force generated by an adductor pollicis (a thumb muscle) undergoing an isometric twitch (a twitch that does not change the muscle’s length). In Figure 1, force is given in newtons (N) and time is given in milliseconds (msec).

4. If an adductor pollicis is stimulated multiple times at a high frequency, it can undergo a tetanic contraction (a sustained muscle contraction that prevents relaxation). In this state, the muscle generates a force that is about 2 times the maximum force generated during an isometric twitch. Based on Figure 1, during a tetanic contraction, the muscle would generate a force of about:

Answer and Explanation

Your Answer is

Correct Answer is G

Explanation

Twice the maximum force, according to figure 1, the maximum force is 7.5, so 7.5×2=15