DATE:
DCHAPTER
ATE :
12
NAME:
NAME :
HANDOUT
DATE :
NAME :
CLASS:
Action Potential (three snapshots)
CLASS
: 12-2
BLM
CLASS:
In this activity you will diagram three aspects of nerve impulse propagation: the resting
potential (polarization), depolarization, and repolarization.
For all three diagrams label the extracellular fluid, the intracellular fluid, the large negative organic ions inside
the neuron, the Na+ voltage-gated channels, the K+ voltage-gated channels, and the sodium-potassium pump and
a voltmeter with two electrodes correctly labelled with the electrical potential or change in electrical potential.
Note: When drawing in the diagrams be sure to keep the colour coding of objects the same.
Resting Potential
Choose a colour to represent the Na+ ions and K+ ions.
To the diagram below, add 10 small sodium ions in the extracellular fluid, 12 slightly larger K + ions in the
intracellular fluid, and 3 Na+ ions and 2 K+ ions being moved by the sodium-potassium pump.
To the right side of the diagram draw a graph of Voltage (mV) vs. Time (milliseconds) for polarization.
Describe the events that occur during polarization.
________________________________________________________
________________________________________________________
________________________________________________________
BC Biology 12 Blackline Master
BLM 12-2 Action Potential (three snapshots)
Copyright © 2013 McGraw-Hill Ryerson Limited
978-1-25-908794-3
DATE:
DCHAPTER
ATE :
12
NAME:
NAME :
HANDOUT
DATE :
NAME :
CLASS:
Action Potential (three snapshots)
CLASS
: 12-2
BLM
CLASS:
Depolarization
To show the movement of Na+ ions during depolarization draw 4 Na+ ions in the intracellular fluid, 7 Na+ ions
in the extracellular fluid, and one Na+ ion passing through each sodium-gated channel in the membrane. To
show the position of the K+ ions during depolarization draw 14 K+ ions in the intracellular fluid.
To the right side of the diagram draw a graph of Voltage (mV) vs. Time (milliseconds) for polarization and
depolarization.
Describe the events that occur during depolarization.
________________________________________________________
________________________________________________________
________________________________________________________
BC Biology 12 Blackline Master
BLM 12-2 Action Potential (three snapshots)
Copyright © 2013 McGraw-Hill Ryerson Limited
978-1-25-908794-3
DATE:
DCHAPTER
ATE :
12
NAME:
NAME :
HANDOUT
DATE :
NAME :
CLASS:
Action Potential (three snapshots)
CLASS
: 12-2
BLM
CLASS:
Repolarization
During repolarization the sodium-gated channels have closed. Draw the positions of the Na+ ions: seven remain
in the extracellular fluid and six are now in the intracellular fluid.
Now draw the movement of K+ ions during repolarization. Place 4 K+ ions in the extracellular fluid, 8 K+ ions
in the intracellular fluid, and one K+ ion passing out through each sodium-gated channel in the membrane.
To the right side of the diagram draw a graph of Voltage (mV) vs. Time (milliseconds) for polarization,
depolarization, and repolarization (include hyperpolarization).
Describe the events that occur during repolarization.
________________________________________________________
________________________________________________________
________________________________________________________
Questions
1. The neuron is not truly “at rest” during the resting potential. Discuss the types of transport that occur.
2. Why does the depolarization move in only one direction?
3. Explain the phenomenon of “overshoot” or hyperpolarization.
BC Biology 12 Blackline Master
BLM 12-2 Action Potential (three snapshots)
Copyright © 2013 McGraw-Hill Ryerson Limited
978-1-25-908794-3