Nervous System Overview
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Questions and Answers

What is the primary function of dendrites?

  • To act as insulators for the neuron
  • To transmit nerve signals away from the cell body
  • To carry nerve impulses in one direction
  • To increase surface area for receiving signals (correct)
  • The axon is responsible for carrying nerve signals in multiple directions.

    False

    What protein is secreted by neuroglial cells to aid the growth and survival of neurons?

    neurotropins

    Myelin is composed of _____% fat and _____% protein.

    <p>75, 25</p> Signup and view all the answers

    Which type of glial cell forms the blood-brain barrier?

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

    Myelinated neurons appear gray due to the presence of myelin.

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

    What are the nodes of Ranvier?

    <p>Indentations in myelinated axons</p> Signup and view all the answers

    The thickening of the axon helps _____ the propagation of nerve impulses.

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

    Match the glial cells with their functions:

    <p>Oligodendrocytes = Make myelin in the CNS Schwann cells = Make myelin in the PNS Microglia = Macrophage of the brain Ependymal cells = Line cavities and secrete CSF</p> Signup and view all the answers

    What happens in demyelination diseases?

    <p>Myelin is removed from the neurons</p> Signup and view all the answers

    Nerve impulses can travel backwards along the axon.

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

    Name one disease associated with demyelination.

    <p>Multiple Sclerosis or Guillain-Barre Syndrome</p> Signup and view all the answers

    Ependymal cells secrete _____ to cushion and protect the brain.

    <p>cerebrospinal fluid</p> Signup and view all the answers

    Which part of the neuron is referred to as the processing center?

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

    Which embryonic layer gives rise to the nervous system?

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

    The optic nerve is considered part of the peripheral nervous system.

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

    What are the two main divisions of the nervous system?

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

    The _____ is the structural unit of the nervous system.

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

    Which cells are responsible for myelinating the peripheral nervous system?

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

    A nerve is a collection of dendrites in the central nervous system.

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

    Name the fastest type of nerve fiber.

    <p>A fibers</p> Signup and view all the answers

    The three parts of the brain stem are the midbrain, _____, and medulla.

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

    Match the following components of the nervous system with their roles.

    <p>Oligodendrocytes = Myelinate central nervous system Sensory Neurons = Transmit information to the brain Motor Neurons = Convey commands from the brain Neurotransmitters = Communicate between neurons</p> Signup and view all the answers

    Which of the following is true about the reflex arc?

    <p>It consists of sensory neuron, interneuron, and motor neuron.</p> Signup and view all the answers

    Myelination increases the speed of nerve impulse conduction.

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

    What are the two subdivisions of the autonomic nervous system?

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

    Cranial nerves and _____ nerves are parts of the peripheral nervous system.

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

    Which type of fiber is the slowest?

    <p>Unmyelinated C fibers</p> Signup and view all the answers

    The action potential can travel in both directions along the axon.

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

    Study Notes

    Nervous System Development

    • Derived from ectoderm during embryonic development.
    • Trilaminar embryo consists of endoderm, mesoderm, and ectoderm; ectoderm gives rise to neuroectoderm (nervous system) and surface ectoderm (skin, hair, nails).
    • Neuroectoderm divides into:
      • Neural tube: forms the Central Nervous System (CNS).
      • Neural crest: forms the Peripheral Nervous System (PNS).

    Myelin and Nerve Cells

    • Myelin in the CNS is produced by oligodendrocytes; in the PNS by Schwann cells.
    • The nervous system is categorized as:
      • Central Nervous System: brain and spinal cord (CNS).
      • Peripheral Nervous System: cranial nerves (12 pairs) and spinal nerves (31 pairs).
    • The optic nerve is classified as part of the CNS despite being a cranial nerve.

    Brain and Spinal Cord Structure

    • Brain components include:
      • Cerebrum: higher functions.
      • Cerebellum: coordination and balance.
      • Brainstem: consists of midbrain, pons, and medulla.
    • Spinal cord consists of different segments: cervical, thoracic, lumbar, sacral, and coccygeal.
    • All spinal nerves are mixed (sensory and motor functions).

    Motor and Sensory Systems

    • Somatic system: voluntary control over skeletal muscles.
    • Autonomic system: involuntary control over glands and organs.
    • Neural impulses travel from the brain to muscles (motor) and from sensory organs to the brain (sensory).

    Neuron Structure

    • Neuron: the fundamental unit of the nervous system, composed of:
      • Dendrites: receive signals, increasing surface area for connectivity.
      • Cell body (soma): processes information and contains nucleus.
      • Axon: transmits nerve signals unidirectionally (orthodromic).
      • Myelin: acts as an insulator, increasing signal transmission speed.

    Action Potential

    • Action potential: the electrical impulse triggering communication between neurons and body functions.
    • Nerve impulses are always unidirectional and travel from axon hillock to axon terminals.
    • Terminals release neurotransmitters to communicate with target organs (other neurons, muscles, glands).

    Myelinated vs. Unmyelinated Fibers

    • Myelinated fibers appear white; unmyelinated fibers appear grey.
    • Myelination allows for faster impulse conduction through saltatory conduction (jumping of impulses at nodes of Ranvier).

    Neuroglial Cells

    • Glial cells support and protect neurons, including:
      • Oligodendrocytes: produce myelin in CNS.
      • Schwann cells: produce myelin in PNS.
      • Astrocytes: form the blood-brain barrier, regulating substance entry into the brain.
      • Microglia: act as immune cells of the CNS.
      • Ependymal cells: line ventricles and secrete cerebrospinal fluid (CSF).

    Neurotrophins

    • Neurotrophins: proteins produced by glial cells that support neuron growth, development, and survival, especially for axons.

    Pathological Considerations

    • Demyelination diseases such as:
      • Multiple sclerosis: an autoimmune disorder attacking CNS myelin.
      • Guillain-Barré syndrome: an autoimmune response affecting PNS myelin.
    • The optic nerve's involvement in multiple sclerosis highlights its unique CNS classification.

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    Description

    Test your knowledge on the development of the nervous system from the ectoderm in this quiz. Learn about the trilaminar embryo and the roles of ectoderm in forming neuroectoderm and the surface ectoderm. Perfect for students looking to consolidate their understanding of embryology.

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