Question 1

Why is the sodium-potassium exchange pump necessary?

Accepted Answer

A)  To establish a resting membrane potential 
B)  To counteract the loss of chloride ions from the cell 
C)  To ensure osmotic balance 
D)  To keep sodium and potassium flux at a steady state 
E)  To maintain equal numbers of positive and negative charges across the membrane 
A)  To establish a resting membrane potential 
B)  To counteract the loss of chloride ions from the cell 
C)  To ensure osmotic balance 
D)  To keep sodium and potassium flux at a steady state 
E)  To maintain equal numbers of positive and negative charges across the membrane

Question 2

Explain what is meant by the equilibrium potential for an ion?

Accepted Answer

The student should explain that the equi

Question 3

In your neurology practice, you meet a patient who complains of a temporary inability to move her legs, a condition that lasts for hours to days at a time. What is your diagnosis, including a description of the molecular mechanism that underlies this condition?

Accepted Answer

The student's answer should identify the

Question 4

In a cell at rest, the driving force on sodium is high, while the permeability of sodium is low. As a consequence, which of the following is true of the cell's membrane potential at rest?

Accepted Answer

A)  Sodium ion concentrations have a small influence on the resting membrane potential. 
B)  Small changes in extracellular sodium concentration will have a large impact on the membrane potential. 
C)  Sodium is at equilibrium at the resting membrane potential. 
D)  Small changes in the intracellular sodium concentration will have a large impact on the membrane potential. 
E)  Sodium ion concentrations do not contribute to the resting membrane potential. 
A)  Sodium ion concentrations have a small influence on the resting membrane potential. 
B)  Small changes in extracellular sodium concentration will have a large impact on the membrane potential. 
C)  Sodium is at equilibrium at the resting membrane potential. 
D)  Small changes in the intracellular sodium concentration will have a large impact on the membrane potential. 
E)  Sodium ion concentrations do not contribute to the resting membrane potential.

Question 5

In the term "steady state," what is steady?

Accepted Answer

A)  The net passive loss of solutes from the cell 
B)  The composition of the cytoplasm 
C)  The leaking of solutes into the cell 
D)  The activity of ion pumps 
E)  The direction in which sodium and potassium are moving 
A)  The net passive loss of solutes from the cell 
B)  The composition of the cytoplasm 
C)  The leaking of solutes into the cell 
D)  The activity of ion pumps 
E)  The direction in which sodium and potassium are moving

Question 6

Which must be true for an ion to be at equilibrium?

Accepted Answer

A)  The concentrations on both sides of the membrane must be equal. 
B)  The electrical gradient must match the concentration gradient in the opposite direction. 
C)  The neuron's membrane potential must be negative. 
D)  The neuron's membrane potential must be positive. 
E)  The permeability of the ion must be zero. 
A)  The concentrations on both sides of the membrane must be equal. 
B)  The electrical gradient must match the concentration gradient in the opposite direction. 
C)  The neuron's membrane potential must be negative. 
D)  The neuron's membrane potential must be positive. 
E)  The permeability of the ion must be zero.

Question 7

In a biological neuron at rest, there is a constant flow of potassium ions out of the cell. This flow is called the

Accepted Answer

A)  restive current. 
B)  sodium-potassium exchange pump current. 
C)  leak current. 
D)  electrogenic current. 
E)  passive current. 
A)  restive current. 
B)  sodium-potassium exchange pump current. 
C)  leak current. 
D)  electrogenic current. 
E)  passive current.

Question 8

In a model cell, positive ions collect on the outer surface of the cell membrane, while anions collect along the inner surface. These ions are effectively removed from the intracellular and extracellular solutions, leaving these solutions

Accepted Answer

A)  electrically charged. 
B)  osmotically balanced. 
C)  ion-deficient. 
D)  electrically neutral. 
E)  osmotically imbalanced. 
A)  electrically charged. 
B)  osmotically balanced. 
C)  ion-deficient. 
D)  electrically neutral. 
E)  osmotically imbalanced.

Question 9

Name two features of the squid giant axon that make it particularly suitable for experiments on membrane potentials.

Accepted Answer

The student's answer should describe tha

Question 10

Describe the following components of the neuron in terms of their electrical properties: The cell membrane, ion equilibrium potentials, ion channels.

Accepted Answer

The student's answer should list the cel

Question 11

The driving force on an ion is defined as the difference between the

Accepted Answer

A)  membrane potential and the threshold potential. 
B)  conductance of an ion and the membrane potential. 
C)  membrane potential and the equilibrium potential for that ion. 
D)  fraction of ions on the intracellular and extracellular membranes. 
E)  sodium and potassium equilibrium potentials. 
A)  membrane potential and the threshold potential. 
B)  conductance of an ion and the membrane potential. 
C)  membrane potential and the equilibrium potential for that ion. 
D)  fraction of ions on the intracellular and extracellular membranes. 
E)  sodium and potassium equilibrium potentials.

Question 12

At rest, a cell's membrane potential is near, but not equal to, the potassium equilibrium potential. Explain why this is the case.

Accepted Answer

The student's answer should explain that

Question 13

Values for neuronal resting membrane potentials vary widely, from -90mV to -40mV. This is primarily due to differences in

Accepted Answer

A)  external potassium concentration. 
B)  external sodium concentration. 
C)  the sodium-potassium exchange pump. 
D)  the chloride conductance. 
E)  the sodium-to-potassium permeability ratio. 
A)  external potassium concentration. 
B)  external sodium concentration. 
C)  the sodium-potassium exchange pump. 
D)  the chloride conductance. 
E)  the sodium-to-potassium permeability ratio.

Question 14

The action of ion channels to allow current to flow through the membrane can be thought of 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 15

Which is a requirement for a neuron to remain in a stable condition?

Accepted Answer

A)  It must have equal concentrations of intracellular sodium and potassium. 
B)  It must be osmotically balanced. 
C)  It must have a small sodium permeability to counteract the sodium-potassium exchange pump. 
D)  It must have a small chloride permeability to counteract the potassium permeability. 
E)  The intracellular solution must be electrically negative compared to the extracellular solution. 
A)  It must have equal concentrations of intracellular sodium and potassium. 
B)  It must be osmotically balanced. 
C)  It must have a small sodium permeability to counteract the sodium-potassium exchange pump. 
D)  It must have a small chloride permeability to counteract the potassium permeability. 
E)  The intracellular solution must be electrically negative compared to the extracellular solution.

Question 16

Ionic conductance is a measure of

Accepted Answer

A)  the electrical charge of an ion. 
B)  the charge strength of an ion. 
C)  the resistance of an ion to movement. 
D)  the equilibrium potential of an ion. 
E)  how easily the ion can move across the membrane. 
A)  the electrical charge of an ion. 
B)  the charge strength of an ion. 
C)  the resistance of an ion to movement. 
D)  the equilibrium potential of an ion. 
E)  how easily the ion can move across the membrane.

Question 17

Which of the following is true for the sodium-potassium exchange pump?

Accepted Answer

A)  It pumps an equal number of ions into and out of the cell. 
B)  It passively distributes ions along their concentration gradient. 
C)  It passively distributes ions along their electrical gradient. 
D)  It pumps two potassium ions into the cell and three sodium ions out of the cell. 
E)  It is unrelated to maintaining ion balance in the cell. 
A)  It pumps an equal number of ions into and out of the cell. 
B)  It passively distributes ions along their concentration gradient. 
C)  It passively distributes ions along their electrical gradient. 
D)  It pumps two potassium ions into the cell and three sodium ions out of the cell. 
E)  It is unrelated to maintaining ion balance in the cell.

Exam 6: Ionic Basis of the Resting Potential

Why is the sodium-potassium exchange pump necessary?

Explain what is meant by the equilibrium potential for an ion?

In your neurology practice, you meet a patient who complains of a temporary inability to move her legs, a condition that lasts for hours to days at a time. What is your diagnosis, including a description of the molecular mechanism that underlies this condition?

In a cell at rest, the driving force on sodium is high, while the permeability of sodium is low. As a consequence, which of the following is true of the cell's membrane potential at rest?

In the term "steady state," what is steady?

Which must be true for an ion to be at equilibrium?

In a biological neuron at rest, there is a constant flow of potassium ions out of the cell. This flow is called the

In a model cell, positive ions collect on the outer surface of the cell membrane, while anions collect along the inner surface. These ions are effectively removed from the intracellular and extracellular solutions, leaving these solutions

Name two features of the squid giant axon that make it particularly suitable for experiments on membrane potentials.

Describe the following components of the neuron in terms of their electrical properties: The cell membrane, ion equilibrium potentials, ion channels.

The driving force on an ion is defined as the difference between the

At rest, a cell's membrane potential is near, but not equal to, the potassium equilibrium potential. Explain why this is the case.

Values for neuronal resting membrane potentials vary widely, from -90mV to -40mV. This is primarily due to differences in

The action of ion channels to allow current to flow through the membrane can be thought of as which of the following electrical components?

Which is a requirement for a neuron to remain in a stable condition?

Ionic conductance is a measure of

Which of the following is true for the sodium-potassium exchange pump?

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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