4

• perineurium surrounds fasicles ( blood nerve permeability barrier)
• endoneurium surrounds connective tissue that supports individual nerve fibers affected in guillan barre
• epineurium surrounds fasicles and blood vessels
• chromatolysis characterized by nissl substance dispersion

  nucleus movement to periphery

  round cell swelling
• Acetylcholine from basal nucleus of meyrnet(forebrain)
• dopamine from substancia nigra and ventral tegmentum increases in huntigton and schizophrenia
• gaba from nucleus accumbenrs decreases in huntigton and anxiety
• norepinephrine from locus ceruleus(pons) inceases in anxiety decreases in depression
• serotonin from raphe nucleus decreases in depression anxiety and parkinsons
• csf flows in the subarachnoid space
• epidural space is a potential space betweeen the dura mater and the skull formation is associated with middle meningeal artery injury
• Blood brain barrier is made of

  • tight junctions between nonfenestrated capillary endothelial cells
  • basement membranes
  • pericytes
  • foot processes of astrocytes
• glucose and amino acids cross BBB via carrier mediated transport mechanism

  lipid soluble/non polar cross faster via diffusion
• circumventricular organs have fenestrated capillaries and no BBB and allow molecules in blood to affect brain functions
• circumventricular organs like

  ovlt ( osmoreceptors)

  neurohypophysis (releases adh)

  area postrema( vomitting after chemotherapy)
• Stroke damages BBB and causes vasogenic edema
• hyperosmolar agents (mannitol) damage BBB and increase permeability to other drugs