Hill Ch 12 TB All
68 Questions
7 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

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?

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

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

    <p>True</p> Signup and view all the answers

    Which glial cells are found in the peripheral nervous system?

    <p>Schwann cells</p> Signup and view all the answers

    Which statement about glial cells is true?

    <p>They help supply metabolic substrates to neurons.</p> Signup and view all the answers

    The separation of positive and negative charges constitutes

    <p>a voltage</p> Signup and view all the answers

    Which statement about membrane capacitance is true?

    <p>It is in series with membrane resistance.</p> Signup and view all the answers

    What is occurring at the membrane?

    <p>Depolarization</p> Signup and view all the answers

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

    <p>the capacitive properties of the membrane</p> Signup and view all the answers

    In the figure, the ______ decreases with distance.

    <p>graded potential</p> Signup and view all the answers

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

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

    The properties shown in the figure can be measured in

    <p>neurons, pacemaker cells, and muscle cells</p> Signup and view all the answers

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

    <p>The resting membrane current</p> Signup and view all the answers

    The figure shows that the membrane potential results from

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

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

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

    Which characteristic is not a factor in the Nernst Equation?

    <p>Capacitance</p> Signup and view all the answers

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

    <p>both active ion transport and passive diffusion of ions</p> Signup and view all the answers

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

    <p>A decrease in the concentration of anions inside the membrane</p> Signup and view all the answers

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

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

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

    <p>its membrane permeability</p> Signup and view all the answers

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

    <p>Voltage-gated Na⁺ channels</p> Signup and view all the answers

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

    <p>I</p> Signup and view all the answers

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

    <p>III and IV</p> Signup and view all the answers

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

    <p>Voltage-gated potassium</p> Signup and view all the answers

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

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

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

    <p>3</p> Signup and view all the answers

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

    <p>An action potential would likely not occur.</p> Signup and view all the answers

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

    <p>the train of action potentials would continue for the length of the stimulating current.</p> 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 ______.

    <p>open; closed; closed</p> 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 ______

    <p>open; inactivated; open</p> Signup and view all the answers

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

    <p>Patch-clamp</p> Signup and view all the answers

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

    <p>inward; Na+</p> Signup and view all the answers

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

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

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

    <p>Voltage-clamp</p> 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 ______.

    <p>hyperpolarised; depolarised</p> Signup and view all the answers

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

    <p>The outward ionic current would disappear.</p> Signup and view all the answers

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

    <p>Voltage-gated potassium channels open.</p> Signup and view all the answers

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

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

    A spiking neuron and a nonspiking neuron share which characteristic?

    <p>Neurotransmitter secretion based on a change in membrane potential</p> Signup and view all the answers

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

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

    The figure depicts a

    <p>cardiac action potential</p> Signup and view all the answers

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

    <p>Voltage-gated Ca2+ channels remain open.</p> Signup and view all the answers

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

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

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

    <p>inactivated voltage-gated sodium channels</p> Signup and view all the answers

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

    <p>Anions migrate into the membrane interior.</p> Signup and view all the answers

    ______ prevents bidirectional propagation of action potentials.

    <p>The inactivation of Na+ channels</p> Signup and view all the answers

    Conduction velocity shows ______ axon diameter.

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

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

    <p>Myelination</p> Signup and view all the answers

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

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

    Compare and contrast nervous systems and endocrine systems.

    <p>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.</p> Signup and view all the answers

    Describe the startle response in the cockroach.

    <p>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.</p> Signup and view all the answers

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

    <p>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.</p> Signup and view all the answers

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

    <p>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.</p> 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?

    <p>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.</p> Signup and view all the answers

    Explain in mechanistic terms how the action potential is an all-or-none phenomenon.

    <p>The action potential is initiated only when a threshold depolarization is reached near the axon hillock. That is, a certain critical number of voltage-gated Na+ channels have to open in order to cause a depolarization that is strong enough to initiate the Hodgkin cycle and, by definition, perpetuate the further opening of voltage-gated Na+ channels via their own depolarization. If the threshold is not reached, there will be no Hodgkin cycle or action potential.</p> Signup and view all the answers

    Compare and contrast the techniques of patch clamping and voltage clamping.

    <p>Both patch clamping and voltage clamping provide experimental information about membrane currents, especially during an action potential. The patch-clamp technique uses a micropipette to record single channel currents, whereas the voltage- clamp technique shows whole cell ionic currents.</p> Signup and view all the answers

    What are the similarities and differences among the channels in the voltage-gated channel superfamily?

    <p>All the voltage-gated channels have principal subunits with extensive sequence homology and thus are evolutionarily related. Voltage-gated Na+ and Ca2+ channels have four domains, whereas the voltage-gated K+ channel has one domain that is homologous to one of the domains on the Na+ channel.</p> Signup and view all the answers

    Explain in mechanistic terms why the action potential can travel a great distance along an axon without degrading.

    <p>The same mechanism that is responsible for the rising phase of the action potential also aids in its perpetuation along the axon without degradation. The action potential on one location on the axon can itself initiate an action potential at a neighboring location, and the induced action potential will have the same all-or-none amplitude as the original.</p> Signup and view all the answers

    Describe the significance of myelination.

    <p>Myelination greatly increases conduction velocity of an axon by increasing the membrane resistance while decreasing the membrane capacitance. In other words, conduction velocity is increased by increasing the length constant without increasing the time constant. Action potentials occur only at the nodes of Ranvier, in a process that is called saltatory conduction.</p> Signup and view all the answers

    The neuron converts an electrical signal to a chemical signal in the

    <p>presynaptic terminal.</p> Signup and view all the answers

    Neurons that relay sensory signals to integrative centers of the CNS are called

    <p>afferent neurons.</p> Signup and view all the answers

    Which glial cells function as metabolic intermediaries between capillaries and neurons?

    <p>Astrocytes</p> Signup and view all the answers

    Which term best describes the movement of ions across a membrane?

    <p>Current</p> Signup and view all the answers

    A decrease in the absolute value of the membrane potential toward zero is called

    <p>Depolarization</p> Signup and view all the answers

    Which of the following actively contributes to the cell’s membrane potential?

    <p>Electrogenic ion pumps</p> Signup and view all the answers

    The time constant (τ) depends on the _______ of the membrane.

    <p>resistance and capacitance</p> 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.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Animal Physiology, Chapter 12: Neurons PDF
    Ch 12 AP 3 PDF
    Ch 12 AP 3 PDF - Neural Tissue & Action Potential

    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.

    More Like This

    The Nervous System
    36 questions

    The Nervous System

    FragrantVibrance avatar
    FragrantVibrance
    Nervous System Cells and Action Potential
    22 questions

    Nervous System Cells and Action Potential

    WellRegardedCactus avatar
    WellRegardedCactus
    Nervous System Organization and Neurons
    5 questions

    Nervous System Organization and Neurons

    CleanlyPeridot5046 avatar
    CleanlyPeridot5046
    The Nervous System Overview
    34 questions

    The Nervous System Overview

    WarmFactorial avatar
    WarmFactorial
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser