INTRO TO NEUROSCIENCE EXAM
PRACTICE TEST SET QUESTIONS
WITH VERIFIED ANSWERS
There are two sets of forces that work in opposition to contribute to the membrane
potential. - Answer-Why are neurons polarized?
Na+, K+, Cl-, A- (proteins) - Answer-What ions contribute to the resting membrane
potential?
K+ and A- (proteins) - Answer-What concentrations are greater inside the cell?
Na+ and Cl- - Answer-What concentrations are greater outside the cell?
These promote equal distribution of ions across the membrane. [concentration
gradients; electrostatic pressure] - Answer-What are homogenizing forces?
Examples?
Sodium/potassium pump; differential permeability. - Answer-Examples of opposing
forces?
The ions are returned by an active, energy required pump. - Answer-How is K+ and
Na+ leakage returned to the normal state?
This is movement of ions from an area of high concentration to an area of low
concentration (happens when there are different ion concentrations on either side of
the membrane.) - Answer-What is diffusion?
This is the force exerted by the attraction of oppositely charged ions or by the
repulsion of similarly charged ions. (this promotes the even distribution of ions). -
Answer-What is electrostatic pressure?
K+ and Cl- pass readily through the resting membrane through leak channels. K+
wants to get out of the cell and moves through its leak channel. The amount of K+
that passes is limited by the electrostatic gradient. - Answer-What is differential
permeability?
There are very few channels open for sodium. - Answer-Why is the membrane only
slightly permeable to sodium?
Charged proteins. - Answer-What cannot cross the membrane?
A sodium-potassium ATPase pump, which used ATP to move the ions against the
concentration gradient. - Answer-How are Na+ and K+ concentrations maintained?
, It causes a net transfer of one positive ion, when it transports 3 Na+ out for 2 K+
moved into the neuron. This will affect the resting potential. - Answer-Why is the
Na/K pump electrogenic?
-70mv, caused by ion distribution. - Answer-What is the average resting membrane
potential under normal conditions?
pushes potassium out of the cell - Answer-What direction does the concentration
gradient push potassium?
pushes potassium into cells - Answer-What direction does the electrical gradient
push potassium?
These require a trigger to open/close (voltage or ligand) - Answer-What are gated
channels?
There is an electrical potential (membrane potential) between the inside of the cell
and the outside. The inside is negative by about -70mV. - Answer-What does it mean
that neurons are polarized?
The separation of charges across the membrane. - Answer-What is membrane
potential?
The movement of ions across the membrane through ions channels. - Answer-What
is current?
Neural potential is becoming more negative than resting membrane potential. -
Answer-What is hyperpolarization?
Neural potential is becoming more positive than resting membrane potential. -
Answer-What is depolarization?
There is not net flux of ions, they enter and leave the neuron at the same rate. This
is achieved by a balance of diffusive force and electrical force. - Answer-What
happens when a neuron is at rest?
This is when there is no net flux. - Answer-What is equilibrium potential?
There is no net flux of ions across the membrane. - Answer-What is the net flux of
ions at equilibrium potential?
They move in the direction that brings the membrane potential closer to the
equilibrium potential. - Answer-In what direction do ions move?
+55mV - Answer-What is the EP of Na+?
-90mV - Answer-What is the EP of K+?
-60mV - Answer-What is the EP of Cl-?
PRACTICE TEST SET QUESTIONS
WITH VERIFIED ANSWERS
There are two sets of forces that work in opposition to contribute to the membrane
potential. - Answer-Why are neurons polarized?
Na+, K+, Cl-, A- (proteins) - Answer-What ions contribute to the resting membrane
potential?
K+ and A- (proteins) - Answer-What concentrations are greater inside the cell?
Na+ and Cl- - Answer-What concentrations are greater outside the cell?
These promote equal distribution of ions across the membrane. [concentration
gradients; electrostatic pressure] - Answer-What are homogenizing forces?
Examples?
Sodium/potassium pump; differential permeability. - Answer-Examples of opposing
forces?
The ions are returned by an active, energy required pump. - Answer-How is K+ and
Na+ leakage returned to the normal state?
This is movement of ions from an area of high concentration to an area of low
concentration (happens when there are different ion concentrations on either side of
the membrane.) - Answer-What is diffusion?
This is the force exerted by the attraction of oppositely charged ions or by the
repulsion of similarly charged ions. (this promotes the even distribution of ions). -
Answer-What is electrostatic pressure?
K+ and Cl- pass readily through the resting membrane through leak channels. K+
wants to get out of the cell and moves through its leak channel. The amount of K+
that passes is limited by the electrostatic gradient. - Answer-What is differential
permeability?
There are very few channels open for sodium. - Answer-Why is the membrane only
slightly permeable to sodium?
Charged proteins. - Answer-What cannot cross the membrane?
A sodium-potassium ATPase pump, which used ATP to move the ions against the
concentration gradient. - Answer-How are Na+ and K+ concentrations maintained?
, It causes a net transfer of one positive ion, when it transports 3 Na+ out for 2 K+
moved into the neuron. This will affect the resting potential. - Answer-Why is the
Na/K pump electrogenic?
-70mv, caused by ion distribution. - Answer-What is the average resting membrane
potential under normal conditions?
pushes potassium out of the cell - Answer-What direction does the concentration
gradient push potassium?
pushes potassium into cells - Answer-What direction does the electrical gradient
push potassium?
These require a trigger to open/close (voltage or ligand) - Answer-What are gated
channels?
There is an electrical potential (membrane potential) between the inside of the cell
and the outside. The inside is negative by about -70mV. - Answer-What does it mean
that neurons are polarized?
The separation of charges across the membrane. - Answer-What is membrane
potential?
The movement of ions across the membrane through ions channels. - Answer-What
is current?
Neural potential is becoming more negative than resting membrane potential. -
Answer-What is hyperpolarization?
Neural potential is becoming more positive than resting membrane potential. -
Answer-What is depolarization?
There is not net flux of ions, they enter and leave the neuron at the same rate. This
is achieved by a balance of diffusive force and electrical force. - Answer-What
happens when a neuron is at rest?
This is when there is no net flux. - Answer-What is equilibrium potential?
There is no net flux of ions across the membrane. - Answer-What is the net flux of
ions at equilibrium potential?
They move in the direction that brings the membrane potential closer to the
equilibrium potential. - Answer-In what direction do ions move?
+55mV - Answer-What is the EP of Na+?
-90mV - Answer-What is the EP of K+?
-60mV - Answer-What is the EP of Cl-?
