Question 1

Action potentials are all-or-none and self-regenerating events.These two properties contribute to which characteristic of action potentials?

Accepted Answer

The fact that action potentials are all-or-none and self-regenerating means that they are conducted without any loss of signal strength. This allows the action potential to propagate down the axon and reach the target cell with the same strength as the original signal.

Question 2

Neuromuscular junctions are synapses between _______ and _______ muscle cells.

Accepted Answer

Neuromuscular junctions are synapses between motor neurons and skeletal muscle cells. Option A and D are incorrect as sensory neurons do not directly synapse with muscle cells. Option B and E are incorrect as interneurons and smooth muscle cells are not involved in neuromuscular junctions.

Question 3

Ion channels may be open continuously, or they may only open or close in response to certain stimuli.The ones that require specific stimuli are known as _______ channels.

Accepted Answer

Gated channels require specific stimuli to open or close, whereas leak channels are continuously open and potassium channels are a type of ion channel that allows the passage of potassium ions. Patch and potential are not types of ion channels.

Question 4

If you knew the intracellular and extracellular concentrations of several ions in a liquid medium bathing cells, what else would you need to know to use the Goldman equation?

Accepted Answer

The Goldman equation calculates the resting membrane potential based on the permeability of the membrane to different ions, their charge, and their concentration gradients across the membrane. Therefore, knowing the membrane permeability for each ion is crucial for its application.

Question 5

Ion transporters and ion channels both contribute to membrane potentials but differ in their requirement for

Accepted Answer

Ion transporters require energy to actively transport ions across the membrane, while ion channels do not require energy and facilitate the passive movement of ions down their concentration gradients.

Question 6

The part of the squid giant axon used by Hodgkin and Huxley to sample ion concentrations was the

Accepted Answer

The squid giant axon was used by Hodgkin and Huxley for their pioneering studies on the ionic basis of action potentials. They sampled ion concentrations in the cytoplasm of the axon, which allowed them to understand how ions move across the neuron's membrane.

Question 7

All of the following are events in an action potential except

Accepted Answer

Opening of leak channels is not an event in an action potential. Leak channels are always open, allowing a small amount of ion movement across the membrane. The events that occur during an action potential include membrane depolarization, opening of voltage-gated channels, reaching threshold, depolarization resulting in the influx of positively charged ions, repolarization resulting in the efflux of positively charged ions, and entering a refractory period.

Question 8

Which statement about axons is false?

Accepted Answer

Saltatory conduction is faster not because ion channels open and close faster than electric current can flow through the cytoplasm, but because the action potential jumps from node to node, skipping the myelinated sections of the axon. This allows the action potential to travel much faster than it would if it had to move through every part of the axon membrane.

Question 9

Refer to the graph showing the tracing of membrane potential change during the course of an action potential.  Which of the following is the correct sequence of events and conditions indicated by the labels "a," "b," "c," and "d"?

Accepted Answer

The correct sequence of events and conditions indicated by the labels "a," "b," "c," and "d" is as follows: Resting potential (a), depolarization (b), repolarization (c), undershoot (d). This is the classic sequence of events in an action potential.

Question 10

Which statement about neuronal membranes is false?

Accepted Answer

The statement that open chloride channels are largely responsible for the resting membrane potential of neurons is false. Instead, resting membrane potential is largely due to the permeability of the membrane to potassium ions, which are more permeable than any other ion at rest. The sodium-potassium pump keeps potassium concentrations higher inside the cell, and membrane potentials tend toward the equilibrium potential of the ion to which the membrane is most permeable. The pump expels sodium ions from inside the cell, which contributes to the negative resting membrane potential.

Question 11

If you wanted to cause a voltage-gated channel in a cell membrane to open, what might you use for a stimulus?

Accepted Answer

Voltage-gated channels open in response to changes in the electrical potential across the cell membrane. Therefore, applying an electrical current to the membrane would be the best stimulus to cause the voltage-gated channel to open. A drug applied to the bathing medium may affect the channel, but it may also have other effects on the cell. Pressure on the membrane or changes in ion concentrations are not reliable stimuli for opening a voltage-gated channel.

Question 12

During an action potential, activation gates in voltage-gated Na⁺ channels close rapidly, but there is a delay in the reopening of their inactivation gates.This contributes to the

Accepted Answer

The delay in the reopening of the inactivation gates of the voltage-gated Na+ channels contributes to the refractory period, during which the neuron is unable to generate another action potential in response to a stimulus. This prevents the action potential from reversing direction and allows for proper signaling in one direction along the axon.

Question 13

The Goldman equation can be used to calculate the equilibrium membrane potential by considering the

Accepted Answer

The Goldman equation takes into account the relative permeabilities of the membrane to all ions that can diffuse across. It considers the electrical charge carried by each ion as well as their concentration gradients. Therefore, choice E is the correct answer. The other options (A, B, and C) are not relevant to the calculation of the equilibrium membrane potential.

Question 14

Refer to the graph showing the tracing of membrane potential change during the course of an action potential.  Which event is occurring in the section of the tracing highlighted in red?

Accepted Answer

The answer of Refer to the graph showing the tracing...

Question 15

When K⁺ ions diffuse out of a resting neuron through open potassium leak channels and leave behind unbalanced negative charges that create a negative membrane potential, that pulls K⁺ back into the neuron.The membrane potential at which the diffusion of K⁺ out of the cell is balanced by the pull of K⁺ into the cell is called the potassium

Accepted Answer

The membrane potential at which the diffusion of potassium ions out of the cell is balanced by the pull of potassium ions into the cell is called the equilibrium potential. This is also known as the Nernst potential or Nernst equilibrium. Therefore, the best choice is D, which is equilibrium potential. The other options may describe related concepts but are not the most appropriate for describing this specific phenomenon.

Question 16

The opening and closing of single ion channels produces tiny electrical currents across the cell membrane, which can be measured by

Accepted Answer

Patch clamping is a technique that allows the measurement of electrical currents produced by the opening and closing of single ion channels across a cell membrane. The technique involves using a microelectrode to create a seal around a small patch of membrane, which allows the recording of the electrical currents produced by individual ion channels. The Goldman equation, Nernst equation, electrochemical gradient and resting potential are all related to the movement of ions across a membrane, but do not directly measure the electrical currents produced by single ion channels.

Question 17

The direction and amount of movement of ions through an ion channel depends on the concentration gradient of the ion as well as on the voltage difference across the membrane.These two forces acting on an ion are called the

Accepted Answer

The two forces acting on an ion through an ion channel are the concentration gradient and voltage difference across the membrane. Together, these forces are known as the electrochemical gradient.

Question 18

When you recorded the membrane potential of a neuron, you noticed that the reading rapidly changed from -60 mV to +50 mV before returning to -60 mV again.What is a possible explanation for this event?

Accepted Answer

The sudden change in membrane potential from -60 mV to +50 mV and then returning to -60 mV is indicative of an action potential, which is a rapid and brief change in membrane potential that allows for nerve impulses to be transmitted along the axon of a neuron. Graded potentials are slower, more local changes in membrane potential, hyperpolarization refers to a change in membrane potential to a more negative value, ionic current flow and opening of leak channels are processes that contribute to changes in membrane potential but do not explain the specific pattern observed in the question.

Question 19

When gated channels open or close the membrane potential of the cell changes.When the inside of a neuron becomes less negative because of the influx of Na⁺ ions, the membrane

Accepted Answer

When the inside of a neuron becomes less negative due to the influx of Na+ ions, the membrane potential moves towards a less negative value, which is called depolarization.

Question 20

Which statement about gated ion channels is false?

Accepted Answer

The resting potential is not produced by gated ion channels, but rather by the unequal distribution of ions across the cell membrane, maintained by ion pumps and transporters.

Quiz 44: Neurons, Glia, and Nervous Systems

Action potentials are all-or-none and self-regenerating events.These two properties contribute to which characteristic of action potentials?

Neuromuscular junctions are synapses between _ and _ muscle cells.

Ion channels may be open continuously, or they may only open or close in response to certain stimuli.The ones that require specific stimuli are known as _______ channels.

If you knew the intracellular and extracellular concentrations of several ions in a liquid medium bathing cells, what else would you need to know to use the Goldman equation?

Ion transporters and ion channels both contribute to membrane potentials but differ in their requirement for

The part of the squid giant axon used by Hodgkin and Huxley to sample ion concentrations was the

All of the following are events in an action potential except

Which statement about axons is false?

Refer to the graph showing the tracing of membrane potential change during the course of an action potential. Which of the following is the correct sequence of events and conditions indicated by the labels "a," "b," "c," and "d"?

Which statement about neuronal membranes is false?

If you wanted to cause a voltage-gated channel in a cell membrane to open, what might you use for a stimulus?

During an action potential, activation gates in voltage-gated Na⁺ channels close rapidly, but there is a delay in the reopening of their inactivation gates.This contributes to the

The Goldman equation can be used to calculate the equilibrium membrane potential by considering the

Refer to the graph showing the tracing of membrane potential change during the course of an action potential. Which event is occurring in the section of the tracing highlighted in red?

The opening and closing of single ion channels produces tiny electrical currents across the cell membrane, which can be measured by

The direction and amount of movement of ions through an ion channel depends on the concentration gradient of the ion as well as on the voltage difference across the membrane.These two forces acting on an ion are called the

When you recorded the membrane potential of a neuron, you noticed that the reading rapidly changed from -60 mV to +50 mV before returning to -60 mV again.What is a possible explanation for this event?

When gated channels open or close the membrane potential of the cell changes.When the inside of a neuron becomes less negative because of the influx of Na⁺ ions, the membrane

Which statement about gated ion channels is false?

Quiz 44: Neurons, Glia, and Nervous Systems

Action potentials are all-or-none and self-regenerating events.These two properties contribute to which characteristic of action potentials?

Neuromuscular junctions are synapses between _______ and _______ muscle cells.

Ion channels may be open continuously, or they may only open or close in response to certain stimuli.The ones that require specific stimuli are known as _______ channels.

If you knew the intracellular and extracellular concentrations of several ions in a liquid medium bathing cells, what else would you need to know to use the Goldman equation?

Ion transporters and ion channels both contribute to membrane potentials but differ in their requirement for

The part of the squid giant axon used by Hodgkin and Huxley to sample ion concentrations was the

All of the following are events in an action potential except

Which statement about axons is false?

Refer to the graph showing the tracing of membrane potential change during the course of an action potential. Which of the following is the correct sequence of events and conditions indicated by the labels "a," "b," "c," and "d"?

Which statement about neuronal membranes is false?

If you wanted to cause a voltage-gated channel in a cell membrane to open, what might you use for a stimulus?

During an action potential, activation gates in voltage-gated Na+ channels close rapidly, but there is a delay in the reopening of their inactivation gates.This contributes to the

The Goldman equation can be used to calculate the equilibrium membrane potential by considering the

Refer to the graph showing the tracing of membrane potential change during the course of an action potential. Which event is occurring in the section of the tracing highlighted in red?

The opening and closing of single ion channels produces tiny electrical currents across the cell membrane, which can be measured by

The direction and amount of movement of ions through an ion channel depends on the concentration gradient of the ion as well as on the voltage difference across the membrane.These two forces acting on an ion are called the

When you recorded the membrane potential of a neuron, you noticed that the reading rapidly changed from -60 mV to +50 mV before returning to -60 mV again.What is a possible explanation for this event?

When gated channels open or close the membrane potential of the cell changes.When the inside of a neuron becomes less negative because of the influx of Na+ ions, the membrane

Which statement about gated ion channels is false?

Neuromuscular junctions are synapses between _ and _ muscle cells.

During an action potential, activation gates in voltage-gated Na⁺ channels close rapidly, but there is a delay in the reopening of their inactivation gates.This contributes to the

When gated channels open or close the membrane potential of the cell changes.When the inside of a neuron becomes less negative because of the influx of Na⁺ ions, the membrane