Neuroglia in the CNS

• Neuroglia in the CNS


  neuroglia in the CNS outnumber neurons + inc astrocytes, microglial cells, ependymal cells + oliogodendrocytes

  like nuerons, most neuroglia have branching processes + a central cell body

  they can be distinguished by their smaller size + darker-staining nuclei
• Astrocytes


  astrocytes = most abundant + versatile glial cells

  their numerous radiating processes cling to neurons + their synaptic endings + cover nearby capillaries

  they support + brace the neurons + anchor them to their nutrient supply lines

  
• Astrocytes' Functions - Exchange & Formation of Synapses


  play a role in making exchanges between capillaries + neurons, heloing determine capillary permeability

  they guide the migration of young neurons + formation of synapses between neurons
• Astrocytes' Functions - Recycling Neurotransmitters


  control chemical enviro around neurons, where their most important job is mopping up leaked potassium ions + recapturing + recycling released neurotransmitters
• Astrocytes' Functions - Calcium Waves

  respond to nearby nerve impulses + released neurotransmitters

  connected by snyapses, astrocytes signal each other w slow-paced intracellular calcium pulses (calcium waves) + by releasing extracellular chem messengers
• Microglial Cells


  small + oviod w relatively thorny processes

  their processes touch nearby neurons, monitoring their health + when they sense that certain neurons r injured/in trouble the microglial cells migrate towards them

  
• Microgial Cells as Macrophages

  where invading microorganisms/dead neurons r present, the microglial cells transform into a special type of macrophage that phagocytises the microorganisms/neuronal debris

  this protective role = important cos cells of the immune system have limited access to CNS
• Ependymal Cells


  range in shape from squamous to columnar + many r ciliated

  they line the central cavities of the brain + spinal cord, where they form a fairly permeable barrier between the cerbrospinal fluid that fills those cavities + the tissue fluid bathing the cells of the CNS

  the beating of their cillia helps to circulate the cerebrospinal fluid that cushions the brain + spinal cord

  
• Oliogodendrocytes

  tho they also branch, oliogodendrocytes have fewer processes than astrocytes

  oliogodendrocytes line up along the thicker nerve fibres in the CNS + wrap their processes tightly around the fibres, producing an insulating covering = myelin sheath