Skeletal Muscle Contraction Report

A contraction in skeletal muscle is caused by specialized intracellular thin and thick filaments, actin and myosin, sliding past each other. Contraction and relaxation of skeletal muscle bring about body movements. These body movements are voluntary and facilitated by the somatic nervous system. Near contact between somatic motor neurons and the muscle fibers are referred to as neuromuscular junctions. It is at the neuromuscular junctions that neurons are able to transmit a signal to the muscle fibers causing muscle contractions. In order to understand physiological mechanisms of skeletal muscle tissue, including twitch recruitment, length-tension relationship, summation, tetanus, fatigue, and temperature, we examined the contraction of an isolated
A higher voltage was needed to see a contraction when directly stimulate the gastrocnemius muscle compared to the stimulation of the sciatic nerve. The gastrocnemius muscle reached a maximal contraction force of 0.8102 N when stretched in length by 3 mm. Contraction force decreased once the gastrocnemius muscle passed optimal strength length. Summation occurred once the sciatic nerve was stimulated twice in succession at the inter-stimulus interval of 100 ms. At the inter-stimulus interval of 40 ms, we saw only one contraction. As we increased the frequency of stimulation, the contraction forces of the peaks and troughs increased. At 1.4 Hz, the peak and trough contraction forces did not differ. When the gastrocnemius muscle was stimulated at the high stimulus frequency of 2 Hz, the contraction force decreased 3.25% per second. The contraction force after the hot (50°C) treatment was significantly larger than both of contractions forces after the cold (4° C) and room temperature (22°C) treatments. There was no significant difference in contraction force after the cold (4°C) and room temperature