Action Potentials: Experiments and Results

LABORATORY REPORT
Activity:

Action Potentials

Name:

Caitlin Magnacca

Instructor:
Date:

03.19.2015

Predictions
Exceeding threshold depolarization at the trigger zone______the likelihood of generation of an action potential. increases Action potential amplitude decreases with distance
Increasing frequency of stimulation to the trigger zone increases 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?

2. Where was membrane potential measured?

3. What was used to measure membrane potential?

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
Axon hillock
Axon

0 V (no stimulation )
-68.5
-68.5

2V
-63.6
-72.4

b. Action Potential Generation.
Laboratory Report/ Caitlin Magnacca/ Action Potentials/ / 03.19.2015/ Page [1] of [4]

Stimulation Voltage
4V
-56.1
-63.8

6V
31.4
31.7

8V
30.9
-68.5

Location

Action potential generated?
Difference in action potential amplitude with distance Stimulation voltage
4V
6V

0 V (no stimulation ) no 2V

8V

no

no

yes

yes

0

8.8

7.7

-0.3

99.4

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?

2. At which stimulation voltage(s) did you see decrimental conduction of graded potential from axon hillock