Nervous system - Lecture Sixteen : Neuroanatomy I - Cells and organisation of the nervous system

5 important questions on Nervous system - Lecture Sixteen : Neuroanatomy I - Cells and organisation of the nervous system

Name and Explain the 2 basic organization of the Nervous system and the types of cells involved ?

Central Nervous System :
  • Consists of the brain and spinal cord.

Peripheral Nervous System :
  • Consists of all peripheral nerves and ganglion.



BOTH organizations are composed of two general cell classes, they are neurons and glia.

Explain the directions of flow in the CNS ?

  • Afferent or ascending : Information than enters to CNS.
  • Efferent or descending : Information or responses that exits the CNS.

Describe the general structure of a neuron and its functional zones ?

  • Dendrites (INPUT ZONE) : Site for receiving input and sending information to the cell body.
  • Cell Body (INPUT ZONE) : Contains a nucleus and organelles. Can receive input.
  • Axon Hillock (SUMMATION ZONE) : Most proximal part of the axon. Sums input.
  • Axon (CONDUCTION ZONE) : May or may not be myelinated. It carries electrical signals.
  • Axon terminals (OUTPUT ZONE) : Ends of the axon. Forms the pre-synaptic component of the synapse & also releases neurotransmitters.
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What are the 5 main types of glial cells and explain their functions ?

  • Astrocytes : Supply nutrients to neurons, ensheath blood capillaries and injury response.
  • Microglia : Immune cells in the CNS and they engulf microorganisms and debris (phagocytes).
  • Ependymal cells : Line fluid-filled spaces in the brain and spinal cord They have cilia to circulate CSF.
  • Oligodendrocytes : Support nerve fibres and ensheath axons in myelin.
  • Schwann Cells : Support peripheral nerves and ensheath axons in myelin.

Explain What a meylin sheath is ?

Myelin sheath is lipid (fat) wrapped around an axon. In the CNS, it is produced in the oligodendrocytes whereas in the PNS, it is produced by Schwann Cells.
Its function is to increase conduction velocity.
  • Nodes of Ranvier : Gaps between the myelin sheaths.

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