Question 1

How would an increase in chloride conductance affect the changes in the membrane potential?

Accepted Answer

The student's answer should explain that increases in chloride conductance will not change the resting membrane potential but will stabilize the membrane potential at a value close to the chloride equilibrium potential.

Question 2

For a cell at rest, increasing the extracellular potassium ion concentration will cause what movement of potassium ions?

Accepted Answer

A)  Potassium ions will move out of the cell. 
B)  Potassium ions will move into the cell. 
C)  Potassium ions will move away from the cell in the extracellular space. 
D)  Potassium ions will not move because the cell is at equilibrium. 
E)  Potassium ions will not move because potassium cannot cross the cell membrane. 
A)  Potassium ions will move out of the cell. 
B)  Potassium ions will move into the cell. 
C)  Potassium ions will move away from the cell in the extracellular space. 
D)  Potassium ions will not move because the cell is at equilibrium. 
E)  Potassium ions will not move because potassium cannot cross the cell membrane. A

Question 3

Which of these is not a factor in determining the membrane potential for a cell?

Accepted Answer

A)  The concentration of sodium ions inside and outside the cell 
B)  The concentration of potassium ions inside and outside the cell 
C)  The relative permeability (or conductance) of the membrane to sodium and potassium ions 
D)  The ratio of the actions of the sodium-potassium exchange 
E)  The type of cell being studied (e.g., glia, muscle, neuron) 
A)  The concentration of sodium ions inside and outside the cell 
B)  The concentration of potassium ions inside and outside the cell 
C)  The relative permeability (or conductance) of the membrane to sodium and potassium ions 
D)  The ratio of the actions of the sodium-potassium exchange 
E)  The type of cell being studied (e.g., glia, muscle, neuron) E

Question 4

Increasing the extracellular potassium concentration causes chloride ions to

Accepted Answer

A)  flow into the cell. 
B)  flow out of the cell. 
C)  accumulate in the extracellular space. 
D)  redistribute to establish equal concentrations on both sides of the cell membrane. 
E)  do nothing; extracellular potassium concentration does not impact chloride ions. 
A)  flow into the cell. 
B)  flow out of the cell. 
C)  accumulate in the extracellular space. 
D)  redistribute to establish equal concentrations on both sides of the cell membrane. 
E)  do nothing; extracellular potassium concentration does not impact chloride ions.

Question 5

The resting membrane potential for a neuron will depolarize (become less negative) with increased extracellular concentration of which of the following ions?

Accepted Answer

A)  Potassium 
B)  Sodium 
C)  Chloride 
D)  Calcium 
E)  Anions 
A)  Potassium 
B)  Sodium 
C)  Chloride 
D)  Calcium 
E)  Anions

Question 6

Why does a neuronal membrane potential change with increases in extracellular potassium concentration, but does not change with an increase in extracellular chloride concentration?

Accepted Answer

The student's answer should describe tha

Question 7

In modifying the Constant Field Equation, why is it necessary to account for the ratio of potassium to sodium permeability?

Accepted Answer

The student's answer should explain that

Question 8

What happens in a squid giant axon when the extracellular chloride concentration is increased?

Accepted Answer

A)  The membrane potential gets more positive (depolarizes). 
B)  The membrane potential gets more negative (hyperpolarizes). 
C)  The membrane potential stays about the same. 
D)  The equilibrium potential for sodium gets more negative. 
E)  The equilibrium potential for sodium gets more positive. 
A)  The membrane potential gets more positive (depolarizes). 
B)  The membrane potential gets more negative (hyperpolarizes). 
C)  The membrane potential stays about the same. 
D)  The equilibrium potential for sodium gets more negative. 
E)  The equilibrium potential for sodium gets more positive.

Question 9

Explain how the sodium-potassium exchange pump contributes to the membrane potential, and how you can predict the magnitude of its effect.

Accepted Answer

The student's answer should describe the

Question 10

Which is true of the potassium equilibrium potential?

Accepted Answer

A)  In neurons, it is usually around 70mV. 
B)  It describes the membrane potential at which all ionic movement stops. 
C)  It predicts the membrane potential when the neuron is at steady state. 
D)  It is the membrane potential where electrical forces and concentration gradients are equal and opposite. 
E)  It plays little or no role in setting the resting membrane potential. 
A)  In neurons, it is usually around 70mV. 
B)  It describes the membrane potential at which all ionic movement stops. 
C)  It predicts the membrane potential when the neuron is at steady state. 
D)  It is the membrane potential where electrical forces and concentration gradients are equal and opposite. 
E)  It plays little or no role in setting the resting membrane potential.

Question 11

What happens when the axoplasm is removed from the giant axon of the squid?

Accepted Answer

A)  Intracellular and extracellular ionic solutions can be controlled and the axon responds normally. 
B)  Anions removed from the intracellular space are lost and the axon loses function. 
C)  Ions from the extracellular space move inward, and the axon has a positive resting potential. 
D)  Ionic concentration can no longer be measured. 
E)  The membrane produces a weak potential that decays over time. 
A)  Intracellular and extracellular ionic solutions can be controlled and the axon responds normally. 
B)  Anions removed from the intracellular space are lost and the axon loses function. 
C)  Ions from the extracellular space move inward, and the axon has a positive resting potential. 
D)  Ionic concentration can no longer be measured. 
E)  The membrane produces a weak potential that decays over time.

Question 12

For a membrane potential to remain stable, which of the following must be true?

Accepted Answer

A)  The potassium conductance must be equal to zero. 
B)  The sum of all ionic currents must be equal to zero. 
C)  The chloride and potassium equilibrium potentials must be the same. 
D)  The chloride and sodium currents must be equal. 
E)  The chloride and potassium conductances must be equal. 
A)  The potassium conductance must be equal to zero. 
B)  The sum of all ionic currents must be equal to zero. 
C)  The chloride and potassium equilibrium potentials must be the same. 
D)  The chloride and sodium currents must be equal. 
E)  The chloride and potassium conductances must be equal.

Question 13

The flow of potassium ions out of the cell is countered by which of the following?

Accepted Answer

A)  An outward flow of chloride ions 
B)  An inward flow of chloride ions 
C)  An outward flow of sodium ions 
D)  An outward flow of calcium ions 
E)  The sodium-potassium exchange pump 
A)  An outward flow of chloride ions 
B)  An inward flow of chloride ions 
C)  An outward flow of sodium ions 
D)  An outward flow of calcium ions 
E)  The sodium-potassium exchange pump

Question 14

At rest, potassium ions exhibit very low current because the tendency for potassium to flow across the cell membrane because of a concentration gradient is opposed by

Accepted Answer

A)  chloride ions moving across the cell membrane because of a concentration gradient. 
B)  sodium ions moving across the cell membrane because of a concentration gradient. 
C)  potassium ions moving across the cell membrane because of the electrical gradient. 
D)  chloride ions moving across the cell membrane because of the electrical gradient. 
E)  sodium ions moving across the cell membrane because of the electrical gradient. 
A)  chloride ions moving across the cell membrane because of a concentration gradient. 
B)  sodium ions moving across the cell membrane because of a concentration gradient. 
C)  potassium ions moving across the cell membrane because of the electrical gradient. 
D)  chloride ions moving across the cell membrane because of the electrical gradient. 
E)  sodium ions moving across the cell membrane because of the electrical gradient.

Question 15

In the squid axon, potassium contributes approximately how much to the resting membrane potential?

Accepted Answer

A)  15% 
B)  30% 
C)  45% 
D)  60% 
E)  75% 
A)  15% 
B)  30% 
C)  45% 
D)  60% 
E)  75%

Question 16

Which of the following is true regarding the sodium permeability for a cell at rest?

Accepted Answer

A)  The sodium permeability is about the same as the potassium permeability. 
B)  The sodium permeability is about 50% smaller than the potassium permeability. 
C)  The sodium permeability is about 75% smaller than the potassium permeability. 
D)  The sodium permeability is about 90% smaller than the potassium permeability. 
E)  The cell membrane is not permeable to sodium at rest. 
A)  The sodium permeability is about the same as the potassium permeability. 
B)  The sodium permeability is about 50% smaller than the potassium permeability. 
C)  The sodium permeability is about 75% smaller than the potassium permeability. 
D)  The sodium permeability is about 90% smaller than the potassium permeability. 
E)  The cell membrane is not permeable to sodium at rest.

Question 17

In retinal ganglion cells, the sodium leak current is relatively large. Explain the effect this has on the resting membrane potential for these cells.

Accepted Answer

The student's answer should describe tha

Question 18

Whether an increase in chloride permeability is hyperpolarizing or depolarizing depends on

Accepted Answer

A)  the equilibrium potential for sodium. 
B)  the relationship between the chloride equilibrium potential and the membrane potential. 
C)  whether there is active transport of chloride across the membrane. 
D)  the equilibrium potential for potassium. 
E)  the neuronal membrane potential. 
A)  the equilibrium potential for sodium. 
B)  the relationship between the chloride equilibrium potential and the membrane potential. 
C)  whether there is active transport of chloride across the membrane. 
D)  the equilibrium potential for potassium. 
E)  the neuronal membrane potential.

Question 19

What is the approximate maximum value that the sodium-potassium exchange pump can contribute to the resting membrane potential?

Accepted Answer

A)  -5 mV 
B)  -11 mV 
C)  -24 mV 
D)  -75 mV 
E)  -90 mV 
A)  -5 mV 
B)  -11 mV 
C)  -24 mV 
D)  -75 mV 
E)  -90 mV

Question 20

The membrane potential of a cell depends on the relative conductances of the membrane to the major ions, and on the

Accepted Answer

A)  permeability of these ions. 
B)  charge of these ions. 
C)  concentrations of these ions. 
D)  size of these ions. 
E)  equilibrium potentials of these ions. 
A)  permeability of these ions. 
B)  charge of these ions. 
C)  concentrations of these ions. 
D)  size of these ions. 
E)  equilibrium potentials of these ions.

Exam 6: Ionic Basis of the Resting Potential

How would an increase in chloride conductance affect the changes in the membrane potential?

For a cell at rest, increasing the extracellular potassium ion concentration will cause what movement of potassium ions?

Which of these is not a factor in determining the membrane potential for a cell?

Increasing the extracellular potassium concentration causes chloride ions to

The resting membrane potential for a neuron will depolarize (become less negative) with increased extracellular concentration of which of the following ions?

Why does a neuronal membrane potential change with increases in extracellular potassium concentration, but does not change with an increase in extracellular chloride concentration?

In modifying the Constant Field Equation, why is it necessary to account for the ratio of potassium to sodium permeability?

What happens in a squid giant axon when the extracellular chloride concentration is increased?

Explain how the sodium-potassium exchange pump contributes to the membrane potential, and how you can predict the magnitude of its effect.

Which is true of the potassium equilibrium potential?

What happens when the axoplasm is removed from the giant axon of the squid?

For a membrane potential to remain stable, which of the following must be true?

The flow of potassium ions out of the cell is countered by which of the following?

At rest, potassium ions exhibit very low current because the tendency for potassium to flow across the cell membrane because of a concentration gradient is opposed by

In the squid axon, potassium contributes approximately how much to the resting membrane potential?

Which of the following is true regarding the sodium permeability for a cell at rest?

In retinal ganglion cells, the sodium leak current is relatively large. Explain the effect this has on the resting membrane potential for these cells.

Whether an increase in chloride permeability is hyperpolarizing or depolarizing depends on

What is the approximate maximum value that the sodium-potassium exchange pump can contribute to the resting membrane potential?

The membrane potential of a cell depends on the relative conductances of the membrane to the major ions, and on the

Principles of Signaling and Organization

Signaling in the Visual System

Functional Architecture of the Visual Cortex

Ion Channels and Signaling

Structure of Ion Channels

Ionic Basis of the Action Potential

Electrical Signaling in Neurons

Ion Transport Across Cell Membranes

Properties and Functions of Neuroglial Cells

Mechanisms of Direct Synaptic Transmission

Indirect Mechanisms of Synaptic Transmission

Release of Neurotransmitters

Neurotransmitters in the Central Nervous System

Transmitter Synthesis, Storage, Transport, and Inactivation

Synaptic Plasticity

The Molecular and Cellular Biology of Synaptic Plasticity

Mechanisms of Extrasynaptic Communication

Autonomic Nervous System

Walking, Flying, and Swimming: Cellular Mechanisms of Sensorimotor Behavior in Invertebrates

Sensory Transduction

Transduction and Transmission in the Retina

Touch, Pain, and Texture Sensation

Auditory and Vestibular Sensation

Constructing Perception

Initiation and Control of Coordinated Muscular Movements

Development of the Nervous System

Critical Periods in Sensory Systems

Regeneration and Repair of Synaptic Connections After Injury

Appendix

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