Pathophysiology of Synaptic Transmission
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Questions and Answers

What is the location where myelin is produced in the Central Nervous System (CNS)?

  • Neurons
  • Oligodendrocytes (correct)
  • Axons
  • Dendrites

What is the primary function of the myelin sheath in the Central Nervous System (CNS)?

  • To increase the speed of impulse conduction along the axon (correct)
  • To slow down the conduction of action potentials
  • To decrease the velocity of propagation of action potentials
  • To increase the diameter of axons

What is the name given to the small gaps in the myelin sheath where myelin is absent?

  • Axonal junctions
  • Neuronal synapses
  • Myelin gaps
  • Nodes of Ranvier (correct)

What is the relationship between axonal diameter and the velocity of propagation of action potentials?

<p>The thicker the axon, the faster the conduction velocity (D)</p> Signup and view all the answers

What is the characteristic of the distribution of voltage-sensitive Na+ and K+ channels in unmyelinated nerve fibers?

<p>They are distributed uniformly along the axon (D)</p> Signup and view all the answers

In myelinated nerve fibers, where are voltage-sensitive Na+ channels clustered in high density?

<p>At the nodes of Ranvier (D)</p> Signup and view all the answers

What is the characteristic of the propagation of action potentials in unmyelinated nerve fibers?

<p>It occurs in a continuous manner (C)</p> Signup and view all the answers

What is the effect of the myelin sheath on the conduction velocity of nerve impulses?

<p>It increases the conduction velocity (B)</p> Signup and view all the answers

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

<p>Initiates action potential and transmits it to the axon (D)</p> Signup and view all the answers

What is the direction of anterograde axonal transport?

<p>From the soma down the axon toward the presynaptic terminal (D)</p> Signup and view all the answers

What is the function of the dendrites in a neuron?

<p>Receive information from other cells (D)</p> Signup and view all the answers

What is the purpose of retrograde axonal transport?

<p>To move substances from the synapse back to the soma (C)</p> Signup and view all the answers

What is the function of the soma in a neuron?

<p>Synthesizes proteins used as neurotransmitters (D)</p> Signup and view all the answers

Where is the myelin sheath produced in the Peripheral Nervous System (PNS)?

<p>By Schwann cells (C)</p> Signup and view all the answers

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

<p>Sends information to other neurons or muscle cells (B)</p> Signup and view all the answers

What is the length range of axons?

<p>Less than 1 mm to up to 1 meter in length (A)</p> Signup and view all the answers

What is the primary location of K+ channels in myelinated axons?

<p>In the internodal area (B)</p> Signup and view all the answers

What is the term for the conduction of action potential in myelinated axons?

<p>Saltatory conduction (A)</p> Signup and view all the answers

What is the percentage of axodendritic synapses in the nervous system?

<p>80-95% (D)</p> Signup and view all the answers

What is the function of axoaxonic synapses?

<p>Modulate transmitter release (B)</p> Signup and view all the answers

What is the term for the transmission of information between neurons?

<p>Synaptic transmission (D)</p> Signup and view all the answers

Which type of synapse is common in invertebrates?

<p>Electrical synapse (B)</p> Signup and view all the answers

What is the term for the region where the axon terminal of one neuron meets the dendrite of another neuron?

<p>Synaptic junction (D)</p> Signup and view all the answers

What is the term for the point of functional contact between axons and skeletal muscle?

<p>Neuromuscular junction (A)</p> Signup and view all the answers

What is the primary mechanism of transmission at an electrical synapse?

<p>Flow of ions through gap junctions (A)</p> Signup and view all the answers

What is the main function of synaptic vesicles?

<p>To store and release neurotransmitters (D)</p> Signup and view all the answers

What triggers the release of neurotransmitters into the synaptic cleft?

<p>The influx of Ca2+ ions through voltage-gated channels (C)</p> Signup and view all the answers

What is the role of the post-synaptic neuron in chemical transmission?

<p>To bind neurotransmitters to receptors (C)</p> Signup and view all the answers

What is the direction of transmission at a chemical synapse?

<p>Unidirectional (B)</p> Signup and view all the answers

What is the space between two neurons that serves as the site for intraneuronal communication?

<p>Synaptic cleft (A)</p> Signup and view all the answers

What is the process by which neurotransmitters are released from the presynaptic terminal?

<p>Exocytosis (B)</p> Signup and view all the answers

What is the primary component of the synapse that receives the signal?

<p>Post-synaptic neuron (C)</p> Signup and view all the answers

What is the primary effect of conformational changes in agent-specific postsynaptic receptors in the narrow synaptic cleft?

<p>Opening or closing of ion channels (B)</p> Signup and view all the answers

What is the primary mechanism by which myasthenia gravis affects neurotransmission at the neuromuscular junction?

<p>Antibodies attack the acetylcholine receptor in the postjunctional folds (B)</p> Signup and view all the answers

What is the characteristic pattern of muscle weakness and fatigability in myasthenia gravis?

<p>Variable in severity and progressive throughout the day (B)</p> Signup and view all the answers

What is the primary effect of acetylcholinesterase inhibitors in myasthenia gravis?

<p>Increasing the efficacy of acetylcholine in the neuromuscular cleft (C)</p> Signup and view all the answers

What is the primary difference between myasthenia gravis and Lambert-Eaton syndrome?

<p>_site of action of the autoimmune response (C)</p> Signup and view all the answers

What is the effect of repetitive stimulation on muscle action potentials in myasthenia gravis?

<p>Progressive decrease in muscle action potentials (A)</p> Signup and view all the answers

What is the characteristic feature of the postjunctional folds in myasthenia gravis?

<p>Decreased localization of acetylcholine receptors (C)</p> Signup and view all the answers

What is the primary effect of the autoimmune response in Lambert-Eaton syndrome?

<p>Reducing the release of acetylcholine from the nerve terminal (B)</p> Signup and view all the answers

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