BIOS252 Week 3 PowerPhys4 Lab Report 2

Topics: Action potential / Pages: 5 (973 words) / Published: Nov 18th, 2014

Activity 4: Generation of Action Potentials


1. Exceeding the threshold depolarization at the trigger zone DECREASES the likelihood of generation of action potential.

2. Action potential amplitude: DOES NOT CHANGE with distance

3. Increasing frequency of stimulation to the trigger zone: DOES NOT increase the production of action potentials.


Experiment 1: Effect of Stimulus Strength on Action Potential Generation

1. Dependent Variable Membrane potential

2. Independent Variable
Stimulus strength (voltage)

3. Controlled Variables
Frequency of stimulation
Type of neuron

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)

4. Which part of the neuron was stimulated? Action potential is first generated in the dendrites of the neuron, or where the neuron receives the action potential of other neurons.

5. Where was membrane potential measured?

6. What was used to measure membrane potential?


See Table 3: Membrane Potentials at Different Stimulation Voltages, by Location
See Graph 1: Maximal depolarization of membrane potential at axon hillock and axon after different stimulation voltages.

1. What was the resting membrane potential (no stimulation) recorded in Table 3?
The Resting Membrane Potential Voltage =-70 mV

2. At which stimulation voltage(s) did you see decrimental conduction of graded potential from axon hillock to axon? At 2V the graded potential went from 64.8 – 73.8

3.At what stimulus voltage(s) did an action potential occur? Action potential occurred at 6V

4. What was the membrane potential at the axon hillock when the action potential was generated? The membrane potential was 30.2 at the axon hillock at 6V when action potential was generated.

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