Neurobiology: Schwann Cells vs Oligodendrocytes
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Questions and Answers

Which sensory receptor is most likely affected in a patient diagnosed with Waardenburg syndrome due to a mutation in the PAX-3 gene?

  • Meissner corpuscle
  • Lamellated corpuscle
  • Ruffini corpuscle (correct)
  • Free nerve ending

    • True or False: Skin does not contain any sensory receptors without the presence of collagen capsules.

  • Depends on the type of skin
  • True
  • Neither true nor false
  • False (correct)

    • What structure increases surface area to maximize contact in a synapse?

  • Myofibrils
  • Terminal Bouton (correct)
  • Synaptic Cleft
  • Perikaryons

    • Which cells are responsible for providing structural and metabolic support to ganglia?

    <p>Neurons and satellite cells of the spinal ganglion</p> Signup and view all the answers

    What best describes the structure of a neuromuscular spindle?

    <p>Contains 2-10 modified skeletal muscle fibers called intrafusal fibers</p> Signup and view all the answers

    What type of neuron is primarily involved in conveying sensory information from skin receptors to the central nervous system?

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

    In Waardenburg syndrome, which of the following neural structures might exhibit dysregulation due to PAX-3 gene mutations?

    <p>Ventral horns of the spinal cord</p> Signup and view all the answers

    Which of the following structures is maximally integrated into touch and pressure sensation?

    <p>Meissner corpuscle</p> Signup and view all the answers

    Which statement correctly describes the location and function of Schwann cells and oligodendrocytes?

    <p>Schwann cells wrap around one axonal segment multiple times in the peripheral nervous system.</p> Signup and view all the answers

    In the context of axon regeneration following nerve injury, which statement is true?

    <p>Regeneration primarily occurs in the segment distal to the injury site.</p> Signup and view all the answers

    What characterizes the rate of axonal regeneration after nerve injury?

    <p>It occurs at a rate of about 100 mm/day.</p> Signup and view all the answers

    Which of the following statements about nerve injury recovery is false?

    <p>Regeneration must first occur in segments proximal to the injury site.</p> Signup and view all the answers

    Which condition is associated with the symptoms of hearing impairment and poliosis in a child?

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

    What is true regarding the role of Schwann cells in nerve injury recovery?

    <p>Their proliferation aids in the repair of the endoneurium.</p> Signup and view all the answers

    Which aspect of the Tinel sign is relevant to nerve injury recovery?

    <p>It indicates advancing regeneration of the injured nerve.</p> Signup and view all the answers

    In the context of myelin production, what is a key difference between Schwann cells and oligodendrocytes?

    <p>Oligodendrocytes can wrap around multiple axonal segments while Schwann cells wrap around a single segment.</p> Signup and view all the answers

    What is the primary function of myelin sheath in large-diameter nerve fibers?

    <p>To facilitate saltatory conduction</p> Signup and view all the answers

    How do Schwann cells contribute to the formation of myelinated fibers?

    <p>They envelop the axon in concentric layers of cytoplasm</p> Signup and view all the answers

    What distinguishes myelinated fibers from non-myelinated fibers?

    <p>Myelinated fibers conduct impulses saltatorily</p> Signup and view all the answers

    What is the maximum number of axons that a single oligodendrocyte can myelinate?

    <p>At least fifty axons</p> Signup and view all the answers

    What role does the mesaxon play in non-myelinated axons?

    <p>It is the junction where Schwann cell cytoplasm meets the axon</p> Signup and view all the answers

    Which type of nerve fibers are typically associated with slower impulse conduction?

    <p>Non-myelinated fibers associated with the autonomic nervous system</p> Signup and view all the answers

    What are large-diameter nerve fibers primarily found in?

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

    Which statement is true about Schwann cells and their myelination of axons?

    <p>Each Schwann cell can myelinate multiple segments of one axon</p> Signup and view all the answers

    What is the primary function of satellite cells in spinal ganglia?

    <p>Providing structural and metabolic support to neurons</p> Signup and view all the answers

    Which layer of connective tissue surrounds individual nerve fibers?

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

    In the structure of a spinal ganglion, which type of neuron is primarily found?

    <p>Pseudo-unipolar neurons</p> Signup and view all the answers

    What is the primary composition of the epineurium?

    <p>Loose collagenous tissue</p> Signup and view all the answers

    What role does the perineurium play in nerve organization?

    <p>It forms a barrier for diffusion into the fascicle.</p> Signup and view all the answers

    What is the significance of the node of Ranvier in nerve fibers?

    <p>It increases the conduction velocity of action potentials.</p> Signup and view all the answers

    Which of the following statements about spinal ganglia is incorrect?

    <p>They consist solely of myelinated fibers.</p> Signup and view all the answers

    What type of tissue surrounds a group of axons forming a nerve fascicle?

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

    What is the primary function of the internode in myelinated axons?

    <p>It insulates the axon to prevent signal loss.</p> Signup and view all the answers

    Which statement best describes the node of Ranvier?

    <p>It allows the propagation of action potentials through saltatory conduction.</p> Signup and view all the answers

    What structure forms the outermost layer of a fascicle in a nerve?

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

    How do Schwann cells contribute to the formation of myelin?

    <p>They form concentric layers of cytoplasm around the axon.</p> Signup and view all the answers

    What is the term used to describe the gaps between adjacent segments of myelin?

    <p>Node of Ranvier</p> Signup and view all the answers

    What role do voltage-gated sodium channels play at the nodes of Ranvier?

    <p>They are involved in the renewal of the action potential.</p> Signup and view all the answers

    In light microscopy, how can individual nerve fibers/axons be identified?

    <p>By the organization of fascicles.</p> Signup and view all the answers

    Which of the following best describes the term 'mesaxon'?

    <p>The site where two Schwann cells meet.</p> Signup and view all the answers

    Study Notes

    Schwann Cells and Oligodendrocytes

    • Schwann cells are located in the peripheral nervous system (PNS), while oligodendrocytes are found in the central nervous system (CNS).
    • A single Schwann cell myelinates one segment of an axon, wrapping around it multiple times.
    • Oligodendrocytes can myelinate multiple segments of one axon and several axons simultaneously.

    Axonal Regeneration

    • Following a traumatic injury to the radial nerve, axonal regeneration occurs at a rate of approximately 100 mm per day.
    • Regeneration happens in the segment distal to the site of damage and is accompanied by Schwann cell proliferation.
    • This process is related to the degeneration and phagocytosis of the endoneurium.

    Waardenburg Syndrome

    • A 2-year-old diagnosed with Waardenburg syndrome exhibits hearing impairment, poliosis, heterochromia, and facial dysmorphisms.
    • This genetic condition is associated with a mutation in the PAX-3 gene, impacting neural crest differentiation.
    • Possible affected structures include neuronal and satellite cells in the spinal ganglion.

    Sensory Receptors

    • The dermis contains various sensory receptors, including:
      • Ruffini corpuscles: responds to pressure and touch.
      • Free nerve endings: detect pain and temperature.
      • Lamellated corpuscles: responsive to vibration.
      • Meissner’s corpuscles: detect light touch.

    Neuromuscular Spindle

    • Neuromuscular spindles help regulate skeletal muscle tone through the spinal stretch reflex.
    • They consist of 2-10 modified skeletal muscle fibers, known as intrafusal fibers.

    Myelinated vs. Non-Myelinated Nerve Fibers

    • Myelinated fibers enable faster impulse conduction through saltatory conduction, characterized by nodes of Ranvier.
    • Non-myelinated fibers have slower conduction speeds and are enveloped by a single layer of Schwann cell cytoplasm.

    Nerve Structure and Organization

    • Endoneurium: loose vascular tissue surrounding individual nerve fibers.
    • Perineurium: fibrous layer encasing nerve fascicles and regulating diffusion.
    • Epineurium: outer layer containing multiple nerve fascicles, blood vessels, and adipose tissue.

    Spinal Ganglion

    • Spinal ganglia house cell bodies of primary sensory neurons, primarily pseudo-unipolar in form.
    • These neurons are surrounded by satellite cells that provide structural and metabolic support.
    • Spinal ganglia are situated along the posterior nerve roots, encapsulated by connective tissue continuous with perineural and epineural sheaths.

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    Description

    Explore the differences between Schwann cells and oligodendrocytes in the nervous system through this quiz. Understand their functions, locations, and how they contribute to myelination in peripheral and central nervous systems. Test your knowledge on neurobiology concepts!

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