Physioex Exercise 3 Activity 1 Exam Questions and Answers Already Passed
A negative membrane potential was recorded when the tip of the microelectrode was - Answers both
inside the cell body and inside the axon
which of the following caused a change in membrane potential from -70 to -40 in the cell body -
Answers an increase in extracellular K+
Which of the following has the most negative voltage - Answers between the inside of the axon and the
outside of the axon with control K+ ECF
Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+
leak channels - Answers the K+ ions move from high concentration to low concentration so when there
is a higher concentration outside of the cell, the K+ ions will be less likely to move out of the cell
Explain why increasing extracellular K+ causes the membrane potential to change to a less negative
value. How well did the results compare with your prediction? - Answers increasing the extracellular K+
increases the positive charge outside the cell which decreases the difference between the inside and
outside of the cell
Explain why a change in extracellular Na+ did not significantly alter the membrane potential in the
resting neuron? - Answers The plasma membrane of a neuron is only slightly permeable to Na+ because
it contains relatively few Na+ leakage channels. This inhibits net diffusion of Na+ into or out of the cell
Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron - Answers the
relative permeability is higher for K+ because there are a lot more channels for it to diffuse through
whereas Na+ has a few because the membrane is selectively permeable to Na+
Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential - Answers
because the membrane is more permeable to K+, a change in K+ conductance will have a greater effect
on the resting membrane potential because the ions will flow into and out of the cell more
What will happen to the resting membrane potential if the extracellular K+ concentration is increased -
Answers the resting membrane potential will become less negative
What is the polarity of the resting membrane potential (voltage) - Answers negative
What does it mean that the voltage just inside the membrane is negative - Answers there are more
negative charges than positive charges just inside the membrane
Which direction would K+ be expected to move (diffuse) through these leak channels - Answers out of
the cell
What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell - Answers it
decreases the net diffusion of K+
A negative membrane potential was recorded when the tip of the microelectrode was - Answers both
inside the cell body and inside the axon
which of the following caused a change in membrane potential from -70 to -40 in the cell body -
Answers an increase in extracellular K+
Which of the following has the most negative voltage - Answers between the inside of the axon and the
outside of the axon with control K+ ECF
Explain why increasing extracellular K+ reduces the net diffusion of K+ out of the neuron through the K+
leak channels - Answers the K+ ions move from high concentration to low concentration so when there
is a higher concentration outside of the cell, the K+ ions will be less likely to move out of the cell
Explain why increasing extracellular K+ causes the membrane potential to change to a less negative
value. How well did the results compare with your prediction? - Answers increasing the extracellular K+
increases the positive charge outside the cell which decreases the difference between the inside and
outside of the cell
Explain why a change in extracellular Na+ did not significantly alter the membrane potential in the
resting neuron? - Answers The plasma membrane of a neuron is only slightly permeable to Na+ because
it contains relatively few Na+ leakage channels. This inhibits net diffusion of Na+ into or out of the cell
Discuss the relative permeability of the membrane to Na+ and K+ in a resting neuron - Answers the
relative permeability is higher for K+ because there are a lot more channels for it to diffuse through
whereas Na+ has a few because the membrane is selectively permeable to Na+
Discuss how a change in Na+ or K+ conductance would affect the resting membrane potential - Answers
because the membrane is more permeable to K+, a change in K+ conductance will have a greater effect
on the resting membrane potential because the ions will flow into and out of the cell more
What will happen to the resting membrane potential if the extracellular K+ concentration is increased -
Answers the resting membrane potential will become less negative
What is the polarity of the resting membrane potential (voltage) - Answers negative
What does it mean that the voltage just inside the membrane is negative - Answers there are more
negative charges than positive charges just inside the membrane
Which direction would K+ be expected to move (diffuse) through these leak channels - Answers out of
the cell
What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell - Answers it
decreases the net diffusion of K+
