Action Potentials in the Locust Leg essays

Action Potentials in the Locust Leg essays The latency period measured from our representative muscle action potential is 8.2 ms (Figure 1). Figure 1 also shows the duration of the action potential, which was measured to be approximately 5 ms. The amplitude measured from baseline to peak was found to be 0.14 V (Figure 1). Dividing this value by the gain, which was set to 200 for this experiment, gives the baseline-to-peak amplitude of 0.7 mV. Three volts was the threshold voltage required to elicit a muscle action potential. Using Method A to calculate the conduction velocity, it was found to be 2.8 m/s (Appendix 1). Using Method B, the conduction velocity was found to be 3.3 m/s (Appendix 1). Figure 2 shows the relationship between stimulus duration and the threshold voltage required for an action potential to occur. As the duration of the stimulus increased, the value of the minimum voltage required to elicit an action potential decreased. The faster the action potential occurs, the shorter the synaptic delay. Following an action potential, the range for the absolute refractory period in the lab manual exercise was found to be 0-2.9 ms. The range for the relative refractory period was 3-6 ms after the action potential. 2. Jumps were seen in the muscle action potentials recorded in response to varying stimulus voltages because of the summation of action potentials from more than one axon. Arthropods have rapid motoneurons. Fast axons have large diameters and low resistances; therefore, they are able to produce phasic, all-or-none action potentials at high velocities. When the applied stimulus was above the threshold voltage, jumps were observed. In addition, during a fast axon depolarization, a rapid leg twitch was observed. There are also slow motoneurons in the arthropod muscle. According to Fourtner and Pearson (1977), slow motoneurons in muscles of the distal leg segments can produce tonic, graded potentials. Invertebrates usually h...