T1 L14: Physiology of Neurons: Electrochemical properties and communication. (HJW)
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Questions and Answers

Which of the following is responsible for the resting membrane potential in neurons?

  • Inward Cl- current
  • Outward Ca2+ current
  • Inward Na+ current
  • Outward K+ current (correct)

    • Which of the following is responsible for depolarization during an action potential?

  • Inward Na+ current (correct)
  • Outward K+ current
  • Outward Ca2+ current
  • Inward Cl- current

    • Which of the following is responsible for the threshold voltage in an action potential?

  • Outward K+ current
  • Inward Cl- current
  • Inward Na+ current (correct)
  • Outward Ca2+ current

    • Which of the following is responsible for repolarization during an action potential?

    <p>Outward K+ current</p> Signup and view all the answers

    According to the text, what is the conduction velocity for an alpha motor neuron?

    <p>100 meters/second</p> Signup and view all the answers

    According to the text, what is the conduction velocity for C fibers responsible for pain?

    <p>1 meter/second</p> Signup and view all the answers

    According to the text, what are the structural differences between alpha motor neurons and C fibers that contribute to the difference in their conduction velocity?

    <p>Alpha motor neurons are myelinated, while C fibers are not.</p> Signup and view all the answers

    According to the text, why do neurons with a larger cross-sectional diameter conduct faster?

    <p>Larger diameter leads to increased conduction velocity because of decreased intracellular resistance.</p> Signup and view all the answers

    Which of the following is true about the resting membrane potential (RMP) if extracellular Na+ concentration increases?

    <p>The RMP becomes slightly less negative</p> Signup and view all the answers

    What happens to the RMP if extracellular K+ concentration suddenly increases?

    <p>The RMP becomes less negative</p> Signup and view all the answers

    Which of the following is NOT a characteristic of action potentials?

    <p>Variable in voltage</p> Signup and view all the answers

    Why do axons need action potentials instead of graded potentials to propagate signals long distances?

    <p>Graded potentials diminish over distance</p> Signup and view all the answers

    Which of the following is true about selective serotonin reuptake inhibitors (SSRIs)?

    <p>SSRIs block the reuptake of serotonin from the synaptic cleft.</p> Signup and view all the answers

    What would happen if the membrane suddenly became 100 times more permeable to Cl¯ ions than to any other ion?

    <p>The membrane potential would become clamped to ECl (e.g. -65 mV).</p> Signup and view all the answers

    What is the effect of sodium channel inactivation on sodium channel activity during the after-hyperpolarization phase of the action potential?

    <p>Initially reduces Na+ conduction, but over time recovery from inactivation occurs.</p> Signup and view all the answers

    How do neurons encode the intensity of a signal?

    <p>Increased frequency of action potentials.</p> Signup and view all the answers

    Which ion's current is half blocked in the presence of this drug?

    <p>K+</p> Signup and view all the answers

    What happens to the resting membrane potential (RMP) when the K+ current is half blocked?

    <p>It becomes more negative</p> Signup and view all the answers

    What effect does doubling the Na/K pump activity have on the RMP?

    <p>It makes it more negative</p> Signup and view all the answers

    By how much does the membrane potential hyperpolarize due to the electrogenic effects of the Na/K pump?

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

    What effect does the drug have on the delayed rectifiers?

    <p>It half blocks them</p> Signup and view all the answers

    What happens to the duration of the action potential when the delayed rectifiers are half blocked?

    <p>It becomes longer</p> Signup and view all the answers

    Which of the following statements is true about the delayed rectifier K+ channels?

    <p>If these channels open immediately upon depolarization, the depolarization would be slower and smaller.</p> Signup and view all the answers

    Which of the following can initiate a subthreshold stimulus in a neuron that might lead to an action potential?

    <p>An electrical signal from a nearby part of the same neuron</p> Signup and view all the answers

    Why does the membrane potential (Vm) become more negative than the resting membrane potential (RMP) during the after-hyperpolarization (AHP)?

    <p>An increased K+ current due to the delayed rectifier</p> Signup and view all the answers

    What would be the equilibrium potential for the nicotinic acetylcholine receptor (nAChR) if it is equally permeable to Na+ and K+?

    <p>-17.5 mV</p> Signup and view all the answers

    Which of the following is responsible for the afterhyperpolarisation (AHP) phase of the action potential?

    <p>Delayed rectifiers</p> Signup and view all the answers

    What is the main transmembrane force acting on an ion during an action potential?

    <p>Electrochemical force</p> Signup and view all the answers

    What is the equilibrium potential for Na+ in a typical cell?

    <p>~ +55 mV</p> Signup and view all the answers

    Why is the resting membrane potential -70 mV despite the presence of positive K+ ions inside the cell?

    <p>K+ ions are balanced by negative ions inside the cell</p> Signup and view all the answers

    Which ion is responsible for the resting membrane potential of -70 mV in a typical cell?

    <p>K+</p> Signup and view all the answers

    What is the main transmembrane force acting on an ion at its equilibrium potential?

    <p>Chemical force</p> Signup and view all the answers

    Which drug class blocks sodium channels as part of their mechanism of action?

    <p>Local anesthetics</p> Signup and view all the answers

    What is the refractory period following an action potential?

    <p>A period of decreased excitability</p> Signup and view all the answers

    What is the purpose of the nervous system?

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

    What is the central nervous system responsible for?

    <p>Information processing</p> Signup and view all the answers

    What is the peripheral nervous system responsible for?

    <p>Motor activation</p> Signup and view all the answers

    Which part of the neuron is responsible for increasing conduction velocity?

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

    What is the main function of the pyramidal cell in the neocortex?

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

    Which type of neuron is responsible for coordination in the cerebellum?

    <p>Perkin G cell</p> Signup and view all the answers

    What is the structure that contains the cell bodies of dorsal root ganglion cells?

    <p>Dorsal root ganglion</p> Signup and view all the answers

    Which cells are able to divide throughout the lifespan and maintain neurons?

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

    Which area of the brain is most rostral in the cerebral cortex?

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

    Which Broadman area corresponds to the sensory cortex?

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

    What is the main difference between neurons and glia?

    <p>Neurons form myelin sheaths</p> Signup and view all the answers

    Which part of the neuron is primarily responsible for sensing and transmitting information?

    <p>Cell body</p> Signup and view all the answers

    What is the purpose of the myelin sheath in neurons?

    <p>To insulate the axon electrically</p> Signup and view all the answers

    What are the nodes of Ranvier in relation to the myelin sheath?

    <p>Gaps in the myelin sheath</p> Signup and view all the answers

    What is the function of the axon terminals in a neuron?

    <p>To transmit electrical signals to other neurons</p> Signup and view all the answers

    Which type of neuron is among the least numerous in the nervous system?

    <p>Bipolar neurons</p> Signup and view all the answers

    What is the main characteristic of pseudo unipolar cells?

    <p>They have two poles but look like they have one</p> Signup and view all the answers

    What is the key feature of chemical synapses?

    <p>They have a large gap between the presynaptic and postsynaptic neuron</p> Signup and view all the answers

    What happens in divergent signaling?

    <p>A single neuron sends signals to multiple neurons</p> Signup and view all the answers

    Which cells are more abundant in the nervous system compared to neurons?

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

    What is the function of glial cells?

    <p>Support and protect neurons</p> Signup and view all the answers

    What is another name for glial cells?

    <p>Neural glia</p> Signup and view all the answers

    What can be observed in the background of the image shown in the text?

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

    What do glial cells do in relation to blood vessels?

    <p>Regulate blood flow</p> Signup and view all the answers

    Which cells are shown as big cells in the image?

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

    What is the main function of glial cells in the nervous system?

    <p>Support and protection</p> Signup and view all the answers

    Which part of the nervous system is derived from the ectoderm?

    <p>Central nervous system</p> Signup and view all the answers

    What is the function of a ganglion in the nervous system?

    <p>Group of cell bodies outside the central nervous system</p> Signup and view all the answers

    Which type of neurons occur only in the central nervous system?

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

    What is the main difference between glia and neurons?

    <p>Glia have no action potentials, while neurons do</p> Signup and view all the answers

    Which cells are able to divide throughout the lifespan and maintain neurons?

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

    Which part of the neuron is responsible for receiving inputs?

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

    What is the function of the myelin sheath in neurons?

    <p>To insulate the axon and increase conduction velocity</p> Signup and view all the answers

    What is the main difference between dorsal and ventral in the brain?

    <p>Dorsal is the upper part of the brain, while ventral is the lower part</p> Signup and view all the answers

    What is the main function of Broadman areas in the cerebral cortex?

    <p>To name and characterize different regions of the cerebral cortex</p> Signup and view all the answers

    Which type of neuron is among the least numerous in the nervous system?

    <p>Bipolar neurons</p> Signup and view all the answers

    What is the key feature of chemical synapses?

    <p>One-way transmission</p> Signup and view all the answers

    What is the main function of convergent connections in the nervous system?

    <p>To integrate multiple inputs into a single neuron</p> Signup and view all the answers

    What is the size of the synaptic cleft in a chemical synapse?

    <p>30 nanometers</p> Signup and view all the answers

    Which part of the neuron is responsible for increasing conduction velocity?

    <p>Myelin sheath</p> Signup and view all the answers

    What is the main difference between neurons and glia?

    <p>Neurons are responsible for transmitting signals, while glia provide support and insulation</p> Signup and view all the answers

    What is the purpose of the myelin sheath in neurons?

    <p>To increase conduction velocity</p> Signup and view all the answers

    What is the main transmembrane force acting on an ion during an action potential?

    <p>Electrical gradient</p> Signup and view all the answers

    What is the main function of glial cells in the nervous system?

    <p>To support and protect neurons</p> Signup and view all the answers

    What is the difference between glial cells and neurons?

    <p>Glial cells are more abundant than neurons</p> Signup and view all the answers

    What are glial cells sometimes called?

    <p>Neural glia</p> Signup and view all the answers

    Which type of cells are supporting cells in the nervous system?

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

    What is the main difference between glial cells and neurons in terms of numbers?

    <p>There are more total glial cells than neurons</p> Signup and view all the answers

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