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Lecture 5

GVPT 100 Lecture Notes - Lecture 5: Resting Potential, Membrane Potential, Myofibril


Department
Government and Politics
Course Code
GVPT 100
Professor
Irwin Morris
Lecture
5

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BSCI207 Exam 4 Review Sheet
Neurons:
1. When Na+ channels open in a neuron during an action potential
a. Na+ ions pour into the cell but the relative Na+ concentrations inside and outside the
cell are essentially unchanged
b. Na+ ions pour into the cell, reversing the relative ion concentrations so that the Na+
concentration becomes higher inside the cell than outside the cell, causing depolarization
c. the net charge throughout the cytoplasm inside the neuron shifts from negative to
positive
d. Both A & C are true
2. From the table of concentrations…
a. Calculate the membrane potential for K+, Na+, and Cl- ions individually (assume
temperature is 37 C).
b. Calculate the membrane potential overall given the permeabilities of the ions listed in
the table
c. What’s the difference in the equations?
Ion
[Ion]in
[Ion]out
Relative Permeability
K+
200 mM
20 mM
10
Na+
15 mM
150 mM
0.1
Cl-
10 mM
120 mM
0.03
3. Fill in the blanks…
At the resting membrane potential, the concentration of K+ is ______ inside the cell than
it is outside and the concentration of Na+ is ________ inside the cell than it is outside.
At resting, more ________ leak channels are open, allowing the ion to move ______ the
cell, causing the internal membrane of the neuron to be more ________ than the outside.
Opening more Na+ channels in the membrane makes the internal surface _______
negative and __________ the cell.
Opening more K+ channels in the membrane makes the internal surface _______
negative and _________ the cell.
4. True or False related to action potentials
a. Action potentials are always the same size
b. A neuron cannot receive multiple signals that sum to bring membrane potential to
threshold
c. When a cell membrane becomes depolarized, K+ channels open
d. At threshold, large numbers of voltage-gated Na+ channels open to allow for a massive
influx of sodium into the cell
e. K+ channels are slow to open and close, causing a hyperpolarization of the neuron
f. During the falling phase of the action potential, there is a refractory period where the
neuron action potential cannot fire again
5. Which of the following would NOT cause an increase in the speed of an action potential?
a. More myelination
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