Action Potentials Essay

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Task 5 - 3report_potentials.pdf Predictions Exceeding threshold depolarization at the trigger zone______the likelihood of generation of an action potential. increases Action potential amplitude does not change with distance Increasing frequency of stimulation to the trigger zone does not change number of action potentials. Materials and Methods Experiment 1: Effect of Stimulus Strength on Action Potential Generation Dependent Variable membrane potential Independent Variable stimulus strength (voltage) Controlled Variables frequency of stimulation, type of neuron Experiment 2: Effect of Frequency of Stimulation on Action Potential Generation Dependent Variable membrane potential Independent Variable frequency of stimulation Controlled Variables stimulus strength (voltage), type of neuron 1. Which part of the neuron was stimulated? trigger zone 2. Where was membrane potential measured? axon 3. What was used to measure membrane potential? voltmeter, patch clamp equipment and electrodes Results Table 3: Membrane Potentials at Different Stimulation Voltages, by Location. a. Values of maximal depolarization of membrane potential (mV) at different stimulation voltages, by location. Location Stimulation Voltage 0 V (no stimulation ) 2 V 4 V 6 V 8 V Axon hillock -68 -63.2 -55.7 29.9 30.6 Axon -67.6 -72.6 -63.9 29.8 -67.6 Laboratory Repor b. Action Potential Generation. Location Stimulation voltage 0 V (no stimulation ) 2 V 4 V 6 V 8 V Action potential generated? NO NO NO YES YES Difference in action potential amplitude with distance -0.4 9.4 8.2 0.1 98.2 Graph 1. Maximal depolarization of membrane potential at axon hillock and axon after different stimulation voltages. Resting membrane potential = -70 mV. 1. What was the resting membrane potential (no stimulation) recorded in Table 3? -68 at Axon Hillock and 67.6 at

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