Regeneration and Plasticity Flashcards
Blood-CSF barrier
-increased vascular network and projections of ependymal cells into the ventricle -choroid plexus
-where the CSF is produced
-there are tight junctions to protect CNS that are between the ependymal cells
*no astrocytes
Blood-brain barrier
-astrocytes induce endothelial cells of vessels to create tight junctions to protect CNS from blood borne pathogens
Brain-CSF barrier
-nutrients delivered from CSF to brain
-waste removed from brain to CSF
Lesion
-any damage to any part of the nervous system (PNS or CNS)
-various levels of severity with varying functional deficits
Causes of lesions
-trauma
-ischemia
-space occupying mass (neoplasia, foreign body)
-inflammation
-infection
-degenerative disorders
-congenital defects/structural abnormalities
Signal transmission
-information within the nervous system is transmitted via action potentials
*unidirectional within the axon and tracts/nerves (Soma to axon to terminal branches to post-synaptic cell)
-afferents (sensory) towards CNS, efferents away from CNS
Neuronal injury
-damage to the axon
-damage to the cell body
Damage to the axon
-PNS= regeneration
-CNS= no regeneration
Damage to the cell body
-no regeneration for either PNS or CNS
-will result in cell death and loss of synapse connection
Proximal vs. distal segments
-proximal segment closest to the CNS, distal segment closer to the tissue (muscle)
-if damage to segment occurs, then there is a chance for regeneration. But if cell body dies then no regeneration
Schwann cells
-myelinating cells of the PNS to provide insulation and reorganization of cell membranes to accelerate AP
-will only myelinated one axon per schwann cell
Oligodendrocytes
-myelinate cells in CNS to help with AP
-can myelinate multiple axons from different neurons
Microglia
-diverse roles in nervous system
-embryological origins are still unclear
-balance of resting and activated glia are critical for homeostasis
Wallerian Degeneration
-an active process of axonal degeneration (distal fragment) following injury in PNS or CNS
Steps of Wallerian Degeneration
1.axonal and myelin degeneration
2.neuronal cell body response
3.re-organization and re-growth