Question 1

Which of the following is true regarding HCN channels in the neuronal membrane?

Accepted Answer

A)  They are responsible for the bulk of the flow of potassium from the cell at rest. 
B)  They are voltage-activated at hyperpolarized membrane potentials. 
C)  They are nonspecific ion channels that allow chloride ions to flow into the cell. 
D)  They have a 4:1 ratio of potassium to sodium, allowing sodium to flow into the cell. 
E)  They are blocked by tetrodotoxin. 
A)  They are responsible for the bulk of the flow of potassium from the cell at rest. 
B)  They are voltage-activated at hyperpolarized membrane potentials. 
C)  They are nonspecific ion channels that allow chloride ions to flow into the cell. 
D)  They have a 4:1 ratio of potassium to sodium, allowing sodium to flow into the cell. 
E)  They are blocked by tetrodotoxin.

Question 2

What is the most abundant source of potassium to flow out of the cell at the resting membrane potential?

Accepted Answer

A)  The sodium-potassium exchange pump 
B)  2P channels 
C)  M channels 
D)  The omega current 
E)  HCN channels 
A)  The sodium-potassium exchange pump 
B)  2P channels 
C)  M channels 
D)  The omega current 
E)  HCN channels

Question 3

In 1902, Bernstein postulated that the membrane potential was due to differences in the concentration of Potassium in the intracellular and extracellular fluids. How did Goldman, Hodgkin and Katz refine this relationship to model the membrane potential more exactly?

Accepted Answer

The student's answer should relate that

Question 4

What happens in a squid giant axon when the extracellular potassium 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 5

The action of the sodium-potassium exchange pump is electrogenic. What does this mean?

Accepted Answer

A)  The exchange pump uses the electrical gradient to pump ions.. 
B)  The exchange pump produces an electrical charge. 
C)  The exchange pump is responsible for the membrane potential. 
D)  The exchange pump counteracts the effect of the electrical gradient. 
E)  The exchange pump uses ions to pump water out of the cell. 
A)  The exchange pump uses the electrical gradient to pump ions.. 
B)  The exchange pump produces an electrical charge. 
C)  The exchange pump is responsible for the membrane potential. 
D)  The exchange pump counteracts the effect of the electrical gradient. 
E)  The exchange pump uses ions to pump water out of the cell.

Question 6

Explain why the charge separation across the cell membrane does not violate the principle of electrical neutrality.

Accepted Answer

The student's answer should describe tha

Question 7

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

Accepted Answer

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

Question 8

In a model cell at rest, what is the relative concentration of potassium inside the cell?

Accepted Answer

A)  Lower than the concentration of potassium outside the cell 
B)  The same as the concentration of potassium outside the cell 
C)  Higher than the concentration of potassium outside the cell 
D)  Lower than the sodium concentration inside the cell 
E)  Lower than the concentration of anions inside the cell 
A)  Lower than the concentration of potassium outside the cell 
B)  The same as the concentration of potassium outside the cell 
C)  Higher than the concentration of potassium outside the cell 
D)  Lower than the sodium concentration inside the cell 
E)  Lower than the concentration of anions inside the cell

Question 9

The equilibrium potential for an ion can be considered as which of the following electrical components?

Accepted Answer

A)  Capacitor 
B)  Battery 
C)  Wires 
D)  Resistor 
E)  Voltmeter 
A)  Capacitor 
B)  Battery 
C)  Wires 
D)  Resistor 
E)  Voltmeter

Question 10

In order to maintain the neuronal membrane potential at steady state, which must occur?

Accepted Answer

A)  ATP must be produced and used by the cell. 
B)  The potassium conductance must be low. 
C)  The membrane must be impermeable to sodium. 
D)  The sodium current must be zero. 
E)  The chloride equilibrium potential must be less than that for potassium. 
A)  ATP must be produced and used by the cell. 
B)  The potassium conductance must be low. 
C)  The membrane must be impermeable to sodium. 
D)  The sodium current must be zero. 
E)  The chloride equilibrium potential must be less than that for potassium.

Question 11

At the neuron's resting membrane potential, chloride ions are at equilibrium; what else must be true?

Accepted Answer

A)  The driving forces on sodium and potassium are equal and in opposite directions. 
B)  The concentrations of sodium and potassium are equal on opposite sides of the membrane. 
C)  The permeability of the membrane to sodium and potassium are equal. 
D)  The ratio of sodium to potassium is equal on opposite sides of the membrane. 
E)  The products of the driving force and permeability for sodium and potassium are equal and opposite. 
A)  The driving forces on sodium and potassium are equal and in opposite directions. 
B)  The concentrations of sodium and potassium are equal on opposite sides of the membrane. 
C)  The permeability of the membrane to sodium and potassium are equal. 
D)  The ratio of sodium to potassium is equal on opposite sides of the membrane. 
E)  The products of the driving force and permeability for sodium and potassium are equal and opposite.

Question 12

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

Accepted Answer

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

Question 13

Name three conditions that must be met for a cell to remain in a stable condition.

Accepted Answer

The student should have the following th

Question 14

The intracellular concentration of sodium in a neuron is

Accepted Answer

A)  much lower than the extracellular concentration. 
B)  somewhat lower than the extracellular concentration. 
C)  the same as the extracellular concentration. 
D)  somewhat higher than the extracellular concentration. 
E)  much higher than the extracellular concentration. 
A)  much lower than the extracellular concentration. 
B)  somewhat lower than the extracellular concentration. 
C)  the same as the extracellular concentration. 
D)  somewhat higher than the extracellular concentration. 
E)  much higher than the extracellular concentration.

Question 15

What is the ratio of sodium to potassium exchange for each cycle of the sodium-potassium exchange pump?

Accepted Answer

A)  1 sodium: 1 potassium 
B)  2 sodium: 1 potassium 
C)  3 sodium: 2 potassium 
D)  2 sodium: 3 potassium 
E)  1 sodium: 2 potassium 
A)  1 sodium: 1 potassium 
B)  2 sodium: 1 potassium 
C)  3 sodium: 2 potassium 
D)  2 sodium: 3 potassium 
E)  1 sodium: 2 potassium

Question 16

Explain how the actions of the sodium-potassium exchange pump maintains a cell's internal concentrations of sodium and potassium.

Accepted Answer

The student's answer should explain that

Question 17

What happens in a model cell when the extracellular chloride concentration is lowered to half its original value?

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 potassium gets more negative. 
E)  The equilibrium potential for potassium 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 potassium gets more negative. 
E)  The equilibrium potential for potassium gets more positive.

Question 18

Which of these conditions is assumed under the constant field equation?

Accepted Answer

A)  Equal conductance for sodium and potassium 
B)  Zero net ionic current 
C)  High chloride conductance 
D)  High potassium conductance 
E)  Low sodium conductance 
A)  Equal conductance for sodium and potassium 
B)  Zero net ionic current 
C)  High chloride conductance 
D)  High potassium conductance 
E)  Low sodium conductance

Question 19

What is the purpose of the constant field equation?

Accepted Answer

A)  To determine the equilibrium potential of a single ion 
B)  To determine the membrane potential when potassium and chloride are present. 
C)  To determine the resting potential of a cell given all ionic concentrations and conductances 
D)  To determine which ions are moving across the membrane at rest 
E)  To determine the minimum voltage at which ionic movement can be balanced 
A)  To determine the equilibrium potential of a single ion 
B)  To determine the membrane potential when potassium and chloride are present. 
C)  To determine the resting potential of a cell given all ionic concentrations and conductances 
D)  To determine which ions are moving across the membrane at rest 
E)  To determine the minimum voltage at which ionic movement can be balanced

Question 20

You are conducting an experiment recording the membrane potential of the squid giant axon. You decide to increase the extracellular concentration of potassium from 10 mM to 30 mM, and then to 200mM. What is the effect on the membrane potential in each case? How do these results compare to the values you would expect from the Nernst equation? Why?

Accepted Answer

The student's answer should describe tha

Exam 6: Ionic Basis of the Resting Potential

Which of the following is true regarding HCN channels in the neuronal membrane?

What is the most abundant source of potassium to flow out of the cell at the resting membrane potential?

In 1902, Bernstein postulated that the membrane potential was due to differences in the concentration of Potassium in the intracellular and extracellular fluids. How did Goldman, Hodgkin and Katz refine this relationship to model the membrane potential more exactly?

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

The action of the sodium-potassium exchange pump is electrogenic. What does this mean?

Explain why the charge separation across the cell membrane does not violate the principle of electrical neutrality.

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

In a model cell at rest, what is the relative concentration of potassium inside the cell?

The equilibrium potential for an ion can be considered as which of the following electrical components?

In order to maintain the neuronal membrane potential at steady state, which must occur?

At the neuron's resting membrane potential, chloride ions are at equilibrium; what else must be true?

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

Name three conditions that must be met for a cell to remain in a stable condition.

The intracellular concentration of sodium in a neuron is

What is the ratio of sodium to potassium exchange for each cycle of the sodium-potassium exchange pump?

Explain how the actions of the sodium-potassium exchange pump maintains a cell's internal concentrations of sodium and potassium.

What happens in a model cell when the extracellular chloride concentration is lowered to half its original value?

Which of these conditions is assumed under the constant field equation?

What is the purpose of the constant field equation?

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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