6.3.2.4 Myelin Sheath

• What is the name of the outermost layer of the nerve fiber shown in the image?

  Myelin sheath
• What is the composition of the myelin sheath?

  It is made of specialized glial cells
• How does the myelin sheath affect neuron function?

  It increases the efficiency of signal transmission
• What is the role of oligodendrocytes in the nervous system?

  They produce myelin in the CNS
• What type of cells produce myelin in the nervous system?

  Glial cells
• What does the image in the study material illustrate?

  Myelin sheaths created by oligodendrocytes and Schwann cells
• What is the name of the gaps between the myelin sheath segments?

  Node of Ranvier
• What are the key features of the myelin sheath?

  • Protective layer of fatty insulation
  • Surrounds the axon of a nerve cell
  • Composed of specialized glial cells (neurolemmocytes)
  • Enables faster and more efficient signal transmission
• How does the structure of a neuron enable efficient signal transmission?

  • Soma receives and integrates signals from dendrites
  • Axon transmits signals rapidly due to myelination and nodes of Ranvier
  • Axon terminals release neurotransmitters to communicate with other neurons or target cells
• How does the structure of the nerve fiber shown in the image contribute to its function?

  • Myelin sheath increases speed of electrical impulse transmission
  • Endonerium and fibrous perineurium provide structural support and protection
  • Arrangement of components allows for efficient and rapid communication along the nerve
• What are the myelin-producing cells in the CNS and PNS?

  • CNS: Oligodendrocytes
  • PNS: Schwann cells
• How do neurolemmocytes contribute to the myelin sheath?

  They wrap around the nerve fiber in segments
• What is the myelin sheath?

  A protective layer of fatty insulation
• What is the name of the long projection that extends from the soma of the neuron?

  Axon
• What is the name of the structure that surrounds the perineurial epithelioid cells?

  Fibrous perineurium
• What is the name of the main part of the neuron?

  Soma
• What is the name of the insulating layer that surrounds the axon?

  Myelin
• What are the main components of the nerve fiber shown in the image?

  • Axon
  • Myelin sheath
  • Endonerium
  • Perineurial epithelioid cells
  • Fibrous perineurium
• How does the severity of multiple sclerosis symptoms vary?

  It varies depending on myelin damage location
• What is the name of the insulating layer that surrounds the axon?

  Myelin
• What is the name of the main part of the neuron?

  Soma
• What is the function of the myelin sheath in the nerve fiber?

  • Increases the speed of electrical impulse transmission along the axon
  • Provides insulation and protection for the axon
• What are the main functions of the different parts of a neuron?

  • Soma: Contains the cell nucleus and organelles, responsible for the neuron's metabolism
  • Dendrites: Receive and transmit signals to the soma
  • Axon: Transmits signals from the soma to other neurons or target cells
  • Myelin sheath: Insulates the axon, increasing the speed of signal transmission
  • Node of Ranvier: Gaps in the myelin sheath that allow rapid signal propagation
• What is the primary function of the myelin sheath?

  To enable faster transmission of electrical signals
• What structural features distinguish oligodendrocytes from Schwann cells?

  • Oligodendrocytes: myelinate multiple axons in CNS
  • Schwann cells: myelinate single axon in PNS
• How does the structure of a neuron relate to its function in the nervous system?

  • Soma and dendrites receive and process information
  • Axon transmits signals over long distances
  • Myelin sheath and nodes of Ranvier enable fast, efficient signal propagation
  • Axon terminals allow communication with other cells
• What is the name of the structure that surrounds the myelin sheath?

  Endonerium
• How does the structure of a neuron relate to its function in the nervous system?

  • Soma and dendrites receive and process information
  • Axon transmits signals over long distances
  • Myelin sheath and nodes of Ranvier enable fast, efficient signal propagation
  • Axon terminals allow communication with other cells
• How does the structure of a neuron support its role in neural communication?

  • Soma integrates inputs from dendrites
  • Axon transmits signals to other neurons or target cells
  • Myelin sheath and nodes of Ranvier facilitate rapid, saltatory conduction
  • Axon terminals release neurotransmitters to influence other cells
• If a patient has multiple sclerosis, which type of microscope would be most useful to visualize the damage to the myelin sheath?

  Scanning electron microscope (SEM)
• What are the key differences between the images (c) and (d) in terms of what they show about the neuron structure?

  • Image (c) shows a cross-section of a myelinated axon at the light microscope level, while image (d) shows the ultrastructure of a myelinated axon at the electron microscope level.
  • Image (c) shows the overall structure of the myelin sheath, while image (d) provides more detailed information about the layered structure of the myelin.
• How does damage to the myelin sheath affect nerve signals?

  It disrupts the flow of electrical signals
• Which type of microscope would be best suited to visualize the detailed ultrastructure of the myelin sheath?

  Transmission electron microscope (TEM)
• What are the symptoms of multiple sclerosis?

  • Muscle weakness
  • Numbness/tingling
  • Vision problems
  • Coordination difficulties
• How do the images (c) and (d) provide complementary information about the structure of a myelinated neuron?

  Image (c) shows the overall structure at the light microscope level, while image (d) provides more detailed ultrastructural information at the electron microscope level
• How does myelin affect nerve signals?

  It prevents nerve signals from leaking out
• What is the primary cause of multiple sclerosis?

  Immune system attacking the myelin sheath
• What are the key features of myelin sheath function?

  • Provides electrical insulation around axons
  • Prevents nerve signals from leaking
  • Enables saltatory conduction
  • Increases speed of signal transmission
• What is the role of Schwann cells in the nervous system?

  They produce myelin in the PNS
• What is the name of the long projection that extends from the soma of the neuron?

  Axon