Neurons and glia

• What is the main controlling and communicating center of the body?

  The nervous system
• What essential functions does the nervous system coordinate and control?


  All essential bodily functions
• How does the nervous system process information from the environment?


  It enables the body to respond accordingly
• What higher functions does the nervous system provide?


  Memory, emotions, and learning
• What is a prototypical neuron characterized by?


  Unidirectional flow of information
• What is the transcriptional and translational activity of neurons?


  Neurons are transcriptionally and translationally very active
• What is a prominent feature of neurons?

  Very prominent nucleolus
• What does it mean that neurons are postmitotic?


  Once specialized, they do not divide
• What is the structure of the neuronal cytoskeleton composed of?


  Microtubules, neurofilaments, and microfilaments
• What is the function of microtubules in neurons?


  Transport within the neuron
• What do neurofilaments provide for neurons?


  Structural maintenance
• What is the role of microfilaments in neurons?


  Structural maintenance and movement of cargo
• What are the two types of motor proteins involved in axonal transport?


  Kinesins and dyneins
• What is the speed of anterograde transport by kinesins?


  100-400 mm/day
• What is the speed of retrograde transport by dyneins?


  50-250 mm/day
• What is myelination and its effect on nerve conduction?


  Myelination speeds up nerve conduction through saltatory conduction
• What are the coverings of peripheral nerves?

  • Endoneurium: Delicate connective tissue layer surrounding axon and Schwann cells
  • Perineurium: Connective tissue layer surrounding groups of axons forming fascicles
  • Epineurium: Robust connective tissue layer surrounding individual fascicles, contains blood vessels
• What does Nissl staining reveal in neurons?


  Nissl staining reveals the cell body, particularly the endoplasmic reticulum
• What is chromatolysis?


  Dissolution of Nissl substance in response to various stressors
• What are the functional classifications of neurons?

  • Sensory/afferent neurons: Send signals towards the CNS
  • Motor/efferent neurons: Send signals away from the CNS
  • Interneurons: Connect neurons within the CNS
• What are the structural classifications of neurons?

  • Multipolar: Most neurons in the CNS (e.g., motor neurons)
  • Bipolar: Rare, e.g., sensory neurons in the retina
  • Pseudo-unipolar: Neurons with a single process that splits into peripheral and central branches
• What type of synapses do neurons connect via?


  Electrical and chemical synapses
• What is the process of signal conversion in chemical synapses?


  Convert electrical signal to chemical signal and back to electrical signal
• What are the types of synapses?

  • Axo-dendritic
  • Axo-somatic
  • Axo-axonic
• What is convergence in neural networks?


  Neurons can receive inputs from tens of thousands of other neurons
• What is divergence in neural networks?


  Neurons can make a binary decision to fire an action potential or not
• What are the major classes of neuroglial cells?

  • Fibrous astrocytes: Support axons in white matter
  • Protoplasmic astrocytes: Homeostatic roles in grey matter
  • Oligodendrocytes: Myelinate multiple axons
  • Microglia: Immune defense and debris removal
  • Ependymal cells: Secrete and circulate cerebro-spinal fluid
• What roles do astrocytes play in the nervous system?


  Structural support, electrolyte homeostasis, energy storage, and neurotransmitter regulation
• How do oligodendrocytes contribute to myelination?


  A single oligodendrocyte can myelinate multiple different axons
• What is the function of microglia?


  Immune defense and removal of cellular debris in the brain
• What is the role of ependymal cells?


  Secrete, monitor, and aid in the circulation of cerebro-spinal fluid
• What are the roles of Schwann cells in the PNS?

  • Myelination of PNS axons (one Schwann cell per axon)
  • Rapid removal of myelin debris by phagocytosis
  • Promote axon regeneration by producing permissive ECM components
• What is the significance of the journal 'Glia'?


  It is an entire scientific journal dedicated to glial cells