Neuroscience Chapter 12: Neurons Quiz

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Questions and Answers

Initiation of the action potential usually occurs ______ of the neuron.

on the dendrites

in the cell body

at the axon initial segment (correct)

on the axon

Which statement about an animal's nervous system is true?

Signal transmission rate is relatively slow.

Neurons form highly discrete lines of communication. (correct)

Action potential signals degrade over distance.

Neurotransmitter is released throughout the body via the blood.

For a hormone to elicit a specific response from a cell, the cell must possess

a synapse

a cell body

dendrites specific to the hormone

receptor proteins specific to the hormone (correct)

Which statement about the startle response of the cockroach is true?

Vibrations of hairs generate nerve impulses in sensory neurons. Signup and view all the answers

At the metathoracic ganglion, the interneurons synaptically inhibit leg motor neurons.

True Signup and view all the answers

Which glial cells are found in the peripheral nervous system?

Schwann cells Signup and view all the answers

Which statement about glial cells is true?

They help supply metabolic substrates to neurons. Signup and view all the answers

The separation of positive and negative charges constitutes

a voltage Signup and view all the answers

Which statement about membrane capacitance is true?

It is in series with membrane resistance. Signup and view all the answers

What is occurring at the membrane?

Depolarization Signup and view all the answers

In the lower panel, the difference between the dashed line and the solid red line is due to

the capacitive properties of the membrane Signup and view all the answers

In the figure, the ______ decreases with distance.

graded potential Signup and view all the answers

Which statement offers the best explanation for the difference between the middle panel and the lower panel?

The membrane voltage measured in the lower panel is farther away from the current pulse. Signup and view all the answers

The properties shown in the figure can be measured in

neurons, pacemaker cells, and muscle cells Signup and view all the answers

Which variable does not contribute to the passive electrical properties of a cell?

The resting membrane current Signup and view all the answers

The figure shows that the membrane potential results from

the overall difference intra- and extra cellular ion concentrations in the volume of cell shown Signup and view all the answers

In the figure, ______ in the center of the cell.

the overall charge neutrality would be maintained independently of the membrane potential Signup and view all the answers

Which characteristic is not a factor in the Nernst Equation?

Capacitance Signup and view all the answers

In a cell, the difference in ion concentration between the intracellular and extracellular fluids results from

both active ion transport and passive diffusion of ions Signup and view all the answers

According to the Nernst equation, which change will depolarize Vm, the membrane potential?

A decrease in the concentration of anions inside the membrane Signup and view all the answers

Which statement regarding the ions in intracellular and extracellular fluids in a standard animal cell is true?

K+ leaks out of the cell slowly because the electrochemical gradient is small. Signup and view all the answers

According to the Goldman equation, the contribution of each ion to the membrane potential depends most on

its membrane permeability Signup and view all the answers

Which structure is most responsible for the all-or-none property of the action potential?

Voltage-gated Na⁺ channels Signup and view all the answers

Which arrow best represents the point where permeability to sodium is the highest?

I Signup and view all the answers

Which arrow best represents the point where the voltage-gated sodium channels are inactivated?

III and IV Signup and view all the answers

______ channels are responsible for the undershoot at point D of the figure.

Voltage-gated potassium Signup and view all the answers

What occurs when the membrane is clamped at -100 mV?

Voltage-gated ion channels do not open at all. Signup and view all the answers

How many separate current pulses cause the membrane potential to reach the threshold?

3 Signup and view all the answers

What would likely occur if stimulus 3 and 6 were performed simultaneously?

An action potential would likely not occur. Signup and view all the answers

If stimulating current pulse 9 (not shown) was both stronger and longer than stimulating current pulse 8, then

the train of action potentials would continue for the length of the stimulating current. Signup and view all the answers

For an axon at resting membrane potential, the K⁺ leak channel is the voltage-gated Na⁺ channel is and the voltage-gated K+ channel is __.

open; closed; closed Signup and view all the answers

During the falling phase of an action potential, the K+ leak channel on the axon is , the voltage-gated Na⁺ channel is , and the voltage-gated K+ channel is __

open; inactivated; open Signup and view all the answers

Which technique was used to collect the data in the bottom panel?

Patch-clamp Signup and view all the answers

On the figure, I represents currents through voltage-gated channels.

inward; Na+ Signup and view all the answers

Why do the channels at II on the figure stay open longer than those at I?

Channels at I become inactivated, whereas channels at II close due to membrane voltage. Signup and view all the answers

Which technique was used to collect the data shown in the figure?

Voltage-clamp Signup and view all the answers

The treatment difference between the membranes shown in the graphs is that the membrane on the left is being while the membrane on the right is being .

hyperpolarised; depolarised Signup and view all the answers

How would the trace on the right look if the neuron was soaking in TEA?

The outward ionic current would disappear. Signup and view all the answers

Which statement about a voltage clamp of a neuron at 0 mV is true?

Voltage-gated potassium channels open. Signup and view all the answers

Which statement regarding the structure of the voltage-gated Na⁺ channels is false?

The channel protein changes its primary structure in response to membrane depolarization. Signup and view all the answers

A spiking neuron and a nonspiking neuron share which characteristic?

Neurotransmitter secretion based on a change in membrane potential Signup and view all the answers

How do nonspiking neurons function even though their depolarization signal significantly degrades with distance?

Voltage-gated K+ channels compensate for the lack of voltage-gated Na⁺ channels. Signup and view all the answers

The figure depicts a

cardiac action potential Signup and view all the answers

What is the best explanation for the plateau shown in the figure?

Voltage-gated Ca2+ channels remain open. Signup and view all the answers

Which statement about ion permeability as shown in the figure is true?

Na+ permeability is at its highest very close to the membrane potential peak. Signup and view all the answers

The absolute refractory period of the action potential is best explained by

inactivated voltage-gated sodium channels Signup and view all the answers

Which statement about a local circuit in an axon is false?

Anions migrate into the membrane interior. Signup and view all the answers

______ prevents bidirectional propagation of action potentials.

The inactivation of Na+ channels Signup and view all the answers

Conduction velocity shows ______ axon diameter.

either a proportional relationship to, or a proportional relationship to the square root of Signup and view all the answers

Considering neurons in living systems, which variable affects conduction velocity the most?

Myelination Signup and view all the answers

Myelination by Schwann cells increases the velocity of action potential propagation by

increasing the resistance and decreasing the capacitance, allowing the action potential to 'jump' over the myelinated area. Signup and view all the answers

Compare and contrast nervous systems and endocrine systems.

Neural and endocrine systems both serve as communication networks within the body. Nervous systems enable fast and precise communication, allowing for fine control. Endocrine systems, in contrast, rely on hormones transported via the bloodstream and often regulate more widespread and long-lasting processes. Signup and view all the answers

Describe the startle response in the cockroach.

When a cockroach senses sudden vibrations or air currents, filiform hairs on its cerci activate sensory neurons. These neurons transmit signals to giant interneurons within the metathoracic ganglion, which then excite motor neurons. Activation of leg motor neurons triggers a rapid withdrawal response, often involving leg movements, allowing the cockroach to escape potential threats. Signup and view all the answers

What are glial cells and how do they aid in the function of the nervous system?

Glial cells provide support and nourishment to neurons. They myelinate axons, increasing conduction velocity, and form a crucial part of the blood-brain barrier, protecting the brain from harmful substances. Signup and view all the answers

Compare and contrast current and voltage with respect to the cell membrane.

Voltage is the potential difference across the membrane due to charge separation, analogous to a battery. Current is the flow of charged particles, such as ions, across the membrane. Signup and view all the answers

Since the bulk solutions that make up the intracellular and extracellular fluids maintain charge neutrality, how does the cell produce membrane potentials?

The membrane potential arises from a localized charge separation across the membrane. Despite the overall neutrality of the fluids, a small number of ions clustering near the membrane are sufficient to create a significant potential difference. Signup and view all the answers

Study Notes

Test Bank Questions - Chapter 12: Neurons

Action Potential Initiation: The action potential typically begins at the axon initial segment of a neuron.
Nervous System Function: The nervous system's communication is routed through discrete neural pathways, not via the bloodstream. Signal transmission is relatively slow compared to other systems.
Hormone Response: For a hormone to trigger a specific cellular response, the cell must possess appropriate receptor proteins.
Cockroach Startle Response: The startle response in cockroaches involves sensory hairs triggering nerve impulses that lead to the spinal cord.
Peripheral Nervous System Glial Cells: Schwann cells are a specific type of glial cell found in the peripheral nervous system.
Glial Cell Function: Glial cells provide metabolic support to neurons.
Membrane Potential Components: Membrane potentials are due to differences in charge separation (voltage).
Membrane Capacitance: Membrane capacitance is the ability of a membrane to store charge; it is in series with membrane resistance.
Graded Potential: A graded potential (in a figure) is a change in membrane voltage that is proportional to the change in the stimulus strength. Depolarization is an increase in membrane potential; hyperpolarization is a decrease.
Action Potential: An action potential is a rapid and substantial change in membrane voltage; it is characterized by a rising phase (depolarization); a falling phase (repolarization); and an undershoot (hyperpolarization).
Sodium and Potassium Channels: Various channels (voltage-gated sodium, voltage-gated potassium) influence action potential.
Passive Electrical Properties: Membrane resistance and capacitance affect the passive electrical properties of a cell.
Cell Membrane Potential: The cellular membrane potential is influenced by the concentration gradients of various ions (like sodium, potassium, and chloride) across the cell.
Nernst Equation: This equation determines the equilibrium potential for a given ion, considering factors like ion concentrations and electrical charge.
Membrane Potential Factors: A number of factors such as membrane resistance and capacitance determines the passive electrical properties of the cell.
All-or-None Principle: Neurons exhibit an all-or-none response in their action potentials depending on whether the voltage at the triggering zone reaches the threshold value. This is a critical property of action potentials in neurons.
Action Potential Phases: Voltage-gated sodium channels open during the rising phase and then become inactivated; voltage-gated potassium channels open during the falling phase.
Refractory Period: The absolute refractory period is when sodium channels are inactivated, preventing further action potentials.
Sodium Channel Inactivation: Sodium channels inactivate during an action potential, leading to the falling phase of the action potential.
Potassium Channels and Undershoot: K+ channel opening and subsequent K+ efflux produce the undershoot phase (hyperpolarization) after an action potential.
Action Potential Conduction Velocity: Factors such as axon diameter and myelination significantly affect conduction velocity of the action potential.
Myelination: Myelination increases the speed of action potential propagation by increasing the resistance and decreasing capacitance of the axon.
Neurotransmitter Release: Neurotransmitter release occurs at the synapse as a result of an action potential triggering the release from the axon terminal.
Neural and Endocrine Communication: Nervous systems exhibit much faster and more precise responses compared to endocrine systems.
Glial Cells: Glial cells support neurons with metabolic intermediaries between capillaries and neurons, maintaining a conducive environment for neural activity.
Current and Voltage: Electric current is the net movement of charge; voltage is charge separation.
Action Potential Mechanism: Ion flow (e.g., sodium influx, potassium efflux) drives the action potential.
Action Potential Characteristics: Action potentials are rapid, large changes in membrane potential that are responsible for signal transmission in neurons.
Pacemaker Cells: Pacemaker cells self-generate action potentials that can be regulated.
Action Potential Measurement Techniques: Specialized techniques, such as the voltage clamp or patch-clamp method, allow for understanding action potential characteristics.
Local Circuit: The local circuit involves current flow within the neuron to propagate the action potential, facilitating rapid and effective transmission.

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Description

Test your knowledge on the key concepts of neurons as explored in Chapter 12. This quiz covers topics such as action potentials, nervous system functions, and the roles of glial cells. Each question challenges your understanding of how neurons work and communicate within the nervous system.