MSP3 NEUROSCIENCE EXAM 1,
LECTURE 2: CELLULAR
NEUROPHYSIOLOGY TEST
QUESTIONS AND ANSWERS
Why does calcium ion not contribute much to the membrane potential? - Answer-It is
used elsewhere throughout the body (like muscle cells)
Why is it important to understand the polarity of the cell and the ratio of ion in:out of
the cell? - Answer-To intuit the nernst equation, we can assume that resting
membrane potential of an ion is +/- 58 mV at a 10 fold concentration difference. If the
ratio is higher or lower, we can assume the charge will be more or less
negative/positive.
If potassium's resting membrane potential is -84 mV, but when measured, the
voltage of the cell is at -70 mV, what direction can we expect potassium to be
moving? - Answer-Out of the cell, so that the positive charges leave, making the cell
more negative
What range is the resting membrane potential for a neuron? - Answer-50-70mV
If the membrane potential is higher/lower than its resting potential, ions will move in
or out of the cell. What determines which ions will move more rapidly? - Answer-The
ions with the most channels available and the permeability
Which of the primary ions involved in neuronal membrane potential is most
permeable? - Answer-Potassium. We know this because its resting potential of K is
closest to the resting potential of a neuron
Which equation do we use to determine the OVERALL resting potential of a cell? -
Answer-The goldman equation, where P = relative permeability of an ion through the
membrane. The equation accounts for the concentration gradients and the relative
permeability
If we wanted to change the membrane potential of a cell, which ion would we target?
- Answer-The ion with the greatest relative permeability (K+ for neurons) because it
can flow in or out of the cell at a faster rate
If you are hyperkalemic (too much potassium outside the cell), what happens to the
cell? - Answer-The membrane potential changes, and can become depolarized
If you are hypokalemic (not enough potassium outside the cell), what happens to the
cell? - Answer-The membrane potential is even more negative, and will be
hyperpolarized (no action potential)
LECTURE 2: CELLULAR
NEUROPHYSIOLOGY TEST
QUESTIONS AND ANSWERS
Why does calcium ion not contribute much to the membrane potential? - Answer-It is
used elsewhere throughout the body (like muscle cells)
Why is it important to understand the polarity of the cell and the ratio of ion in:out of
the cell? - Answer-To intuit the nernst equation, we can assume that resting
membrane potential of an ion is +/- 58 mV at a 10 fold concentration difference. If the
ratio is higher or lower, we can assume the charge will be more or less
negative/positive.
If potassium's resting membrane potential is -84 mV, but when measured, the
voltage of the cell is at -70 mV, what direction can we expect potassium to be
moving? - Answer-Out of the cell, so that the positive charges leave, making the cell
more negative
What range is the resting membrane potential for a neuron? - Answer-50-70mV
If the membrane potential is higher/lower than its resting potential, ions will move in
or out of the cell. What determines which ions will move more rapidly? - Answer-The
ions with the most channels available and the permeability
Which of the primary ions involved in neuronal membrane potential is most
permeable? - Answer-Potassium. We know this because its resting potential of K is
closest to the resting potential of a neuron
Which equation do we use to determine the OVERALL resting potential of a cell? -
Answer-The goldman equation, where P = relative permeability of an ion through the
membrane. The equation accounts for the concentration gradients and the relative
permeability
If we wanted to change the membrane potential of a cell, which ion would we target?
- Answer-The ion with the greatest relative permeability (K+ for neurons) because it
can flow in or out of the cell at a faster rate
If you are hyperkalemic (too much potassium outside the cell), what happens to the
cell? - Answer-The membrane potential changes, and can become depolarized
If you are hypokalemic (not enough potassium outside the cell), what happens to the
cell? - Answer-The membrane potential is even more negative, and will be
hyperpolarized (no action potential)
