Nervous Tissue

• What are neurons also known as?


  Nerve cells
• What is the primary function of neurons?


  They are specialized cells that receive and send signals to other cells.
• What are the main parts of a neuron?


  1. Cell Body
  2. Dendrites
  3. Axon
• What is another name for the cell body of a neuron?

  Perikaryon or soma
• What is the role of the cell body in a neuron?


  It serves as the metabolic and genetic center of the neuron.
• How does the volume of the cell body compare to the total volume of the neuron?


  The cell body makes up a small part of the neuron’s total volume.
• What is the function of dendrites in a neuron?


  Dendrites are the receptive part of the neuron.
• What is unique about the surface of dendrites?


  Their receptive surface is larger than the cell body.
• What is the axon in a neuron?


  The axon is the conducting portion of the neuron.
• What is the structure of an axon?


  An axon is a cylindrical tube of cytoplasm and cytoskeleton covered by axolemma.
• What covers the axon?


  The axon is covered by supporting cells and frequently myelin.
• What are the two types of axoplasmic flow?


  1. Anterograde Transport
  2. Retrograde Transport
• What is anterograde transport in neurons?


  It carries cell body nutrients in a forward direction to the axon termination.
• What is the purpose of anterograde transport?


  To maintain axonal structure and synthesize neurotransmitters.
• What is retrograde transport in neurons?


  It occurs from the distal end of the axon back to the cell body.
• What is the purpose of retrograde transport?


  To return used or worn-out materials to the cell body for restoration.
• How do neurons differ from interneurons?


  • Neurons have large cell bodies and long axons.
  • Interneurons have small cell bodies and short axons.
  • Neurons transmit impulses quickly over long distances.
  • Interneurons transmit impulses locally.
• What are the anatomical types of neurons?


  1. Unipolar
  2. Bipolar
  3. Multipolar
• What characterizes unipolar neurons?


  A unipolar neuron has a single axon that divides into two branches.
• Where are unipolar neurons found?


  In the ganglia of spinal nerves and some cranial nerves.
• What characterizes bipolar neurons?


  Bipolar neurons have an elongated cell body with one axon and one dendrite.
• Where are bipolar neurons found?


  In retinal cells, sensory cochlear, and vestibular ganglia.
• What characterizes multipolar neurons?

  Multipolar neurons possess a single axon and many dendrites.
• Which type of neuron is the most common?

  Multipolar neurons
• What are the functional types of neurons?

  1. Afferent/Sensory Neuron: Receives impulses and transmits toward CNS.
  2. Efferent/Motor Neuron: Transmits impulses from CNS toward effector organs.
• How do neuroglia compare to neurons in number?


  Neuroglia outnumber neurons by 10:1.
• Do neuroglia form synapses?


  No, neuroglia do not form synapses.
• What are the functions of neuroglia?


  1. Supporting cells
  2. Nutritive function – connect capillary to neurons
• What are the major types of neuroglia?


  1. Macroglia
  2. Microglia
• What are the two types of macroglia?


  Astrocytes and oligodendrocytes
• What is the role of astrocytes in the nervous system?

  Astrocytes provide structural support and maintain ion concentrations.
• What are the two types of astrocytes?


  Protoplasmic and fibrous astrocytes.
• Where do protoplasmic astrocytes occur?


  In gray matter.
• Where do fibrous astrocytes occur?


  In white matter.
• What are the functions of astrocytes?


  1. Provide structural support
  2. Direct neural migration during development
  3. Maintain appropriate concentrations of ions (K+) in extracellular space
  4. Contribute to formation of blood-brain barrier
  5. Participate in reuptake of neurotransmitters
  6. Aid in repair of damaged neural tissue
• What are ependymal cells also known as?


  Ependymocytes
• What is the structure of ependymal cells?


  They form a single layer of cuboidal or columnar cells.
• What do ependymal cells possess that aids in their function?


  They possess microvilli or cilia.
• What is the function of the cilia on ependymal cells?


  The movements of cilia contribute to the flow of cerebrospinal fluid (CSF).
• What are the functions of ependymal cells?


  1. Line the cavities of the brain and central canal of the spinal cord
  2. Assist in the circulation of CSF
  3. Produce CSF in choroid plexuses