Muscle Contraction

In: Science

Submitted By harrisco
Words 425
Pages 2
Conor Harris
11/9/2015

In the experiment we performed in lab last week, our group’s objective was to measure the force output in the unit of Newtons (N) and Electromyography (EMG) output of an isometric hand contraction squeezing a ball in four varying wrist angles. This experiment was created with the intention to help us better understand how muscle force varies when muscle length varies. The title of the experiment is the “Length-Tension Experiment”. The Length-Tension relationship in anatomy refers to how the number of crossbridges depends on the amount of overlap between thick and thin fibers. Optimum amount of overlap will result in the greatest amount of tension. The optimum amount of overlap can be determined by the length of the sacromeres when the muscle is contracted. If the muscles are too stretched when contraction occurs, myosin will pull away from the actin and prevent cross bridge formation. Conversely, if muscles/sacromeres are too short at contraction cannot conduct signal efficiently because the crowded thin filaments disrupt the t-tubule’s arrangement in the myofibers. It is also essential to comprehend the relationship between myosin and actin. Myosin (thick filaments in sacromere) grabs onto actin (thin filaments in sacromere) and pulls, creating tension in the muscle. The contraction is caused by the previously described interaction between actin and myosin, resulting in the thin filaments being pulled closer to the M line of the sacromere, widening the zone of overlap between the two more and more until the sacromeres are fully shortened. Understanding this knowledge helped us interpret our results of the experiment much more effectively. As seen in Figure 1 below, our results were interesting, but not entirely what we expected. Our group predicted increasing force as the wrist angle came closer to neutral (180 degrees), but one of…...

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