Powerphys4

LABORATORY REPORT

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Activity: Name: Instructor: Date:

Action Potentials November 16, 2014

Predictions

1. Exceeding threshold depolarization at the trigger zone _____ the likelihood of generation of an action potential. increases 2. Action potential amplitude decreases with distance. 3. Increasing frequency of stimulation to the trigger zone decreases number of action potentials.

Materials and Methods

Experiment 1: Effect of Stimulus Strength on Action Potential Generation 1. Dependent Variable. membrane potential 2. Independent Variable. stimulus strength (voltage) 3. Controlled Variables. type of neuron; frequency of stimulation

Experiment 2: Effect of Frequency of Stimulation on Action Potential Generation 1. Dependent Variable. membrane potential 2. Independent Variable. frequency of stimulation 3. Controlled Variables. type of neuron; stimulus strength (voltage)

1. Which part of the neuron was stimulated? undefined

Trigger zone

2. Where was membrane potential measured? undefined

Along different spots, axion hilloc

3. What was used to measure membrane potential? undefined

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 0 V (no stimulation ) Axon hillock -68 2V -63.4 Stimulation voltage 4V 6V -55.9 29.7 8V 30.8

Location 0 V (no stimulation ) -67 2V -72.3

Stimulation voltage 4V 6V -64.2 29.9

8V 31.1

Axon

b. Action Potential Generation.

Action potential generated? Difference in action potential amplitude with distance No -1 No 8.9 No 8.3 Yes -0.2 Yes -0.3

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...