nervous tissue

• nervous tissue -> ALL nervous tissue consists of..

  1. nerve cells = NEURONS
  2. supporting cells = glial cells
  3. blood vessels
• nervous tissue -> typical neuron (nerve cell) has ....

  • what a normal cell has
  • cell body/soma (nucleus, cytoplasm)
  • multiple dendrites (extensions of plasma membrane)
  • one axon (extensions of plasma membrane)
  • mitochondria, golgi, RER
  • Microtubules and neurofilaments
  • Lipofuscin – undigested material from lysosomes

  A) body

  
• nervous tissue -> supporting/glial cells

  • Neuron homeostasis, scar formation, mop-up neurotransmitters etc
  • 3 types of glial cells in central nervous system: astrocytes, oligodendrocytes, microglia
  • peripheral nervous system: schwann cells

  
• nervous tissue -> glial cell diagram

  A) glial cell

  B) nucleus

  
• nervous tissue -> glial cells -> myelination

  • myelin: a fatty cover, aiding signal transduction speed
  • axons can be myelinated
  • glial cells which produce myelin are:
  • CentralNS: oligodendrytes
  • PeripheralNS: schwann cells

  
• nervous tissue -> glial/supporting cells

  • oligodendrocyte = glial cell of central nervous system. It has branches which wrap around parts of 12 AXONS
  • Schwann cell = glial cell of peripheral nervous system. cell membranes of schwann cells wrap around parts of 1 axon

  
• nervous tissue -> peripheral nerves contain...

  A) connective

  B) axons

  C) schwann

  
• CNS vs PNS

  
• nervous tissue -> peripheral nerves DIAGRAM

  • epineurium: yellow coloured, around nerves (big)
  • perineurium: around fascicles of myelin (medium)
  • endoneurium: around myelin's (very small)

  
• nervous tissue -> nerve FASCICLE diagram of Schwann cell

  • dark black lines = myelin
  • Schwann cells only support one part in one axon in PNS

  
• nervous tissue -> peripheral nerve DIAGRAM

  • no myelination: slow impulse speeds
  • myelin: insulates the axon, increases the speed of signals transmitted between neurons

  
• nervous tissue -> definition of myelin REMINDER

  • myelin: insulates the axon, increases the speed of signals transmitted between neurons

  A) myelin

  B) dentrite

  
• axon vs dendrite

  • axon: long, unbranched, one axon per neuron
  • dendrites: shorter, highly branched, many dendrites per neuron

  A) dendrite

  B) axon

  
• nervous tissue -> myelinated vs unmyelinated nerves

  • the more axons with myelin around them, the faster signals are transmitted

  
• nervous tissue -> PNS -> GANGLIA

  • they're groups of neuron cell bodies that are packed closely
  • neurons and glial (Schwann) cells are scattered

  
• grey vs white matter

  • grey: neurons and glial cells
  • white: myelinated fibers