Neurosurgery notes/Anatomy/CSF anatomy/BBB

BBB

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Parent item
CSF anatomy
Sub-item
Glymphatics
Circumventricular organs

General

  • Areas of brain without BBB (aka Circumventricular organs as these are specialized areas in the walls of third and fourth ventricles)
  • Fluid compartments in the brain consist of
    • Intracellular fluid (ICF) (60-68%)
    • Interstitial fluid (ISF) (or extracellular fluid) (12-20%)
    • Blood (10%)
    • CSF (10%)

Components

  • Pericytes
    • 3:1 ratio, pericyte to endothelial ratio
  • Endothelial cells
  • Astrocytes
    • Foot like processes
    • Maintain tight junction
    • Foot processes of astrocytes. Cover about 85% of the capillary surface.
  • Immune cells (there is a meningeal-lymphatic system that is newly discovered)
    • Macrophage/monocytes
      • Within Virchow robin space
    • Mast cells
    • Microglia
      • Lives in Virchow robin spaces
      • Antigen presentation>phagocytosis
  • Basement membrane
notion image
Tight junction between endothelial cells Capillary lumen Basement membrane Foot process of astrocyte Endothelial cell

Molecular control (only small lipophilic material can cross

  • Tight junctions
  • Adherence protein
  • Transporters
    • Glycoprotein P
    • GLUT1

Movements

  • Pinocytosis
  • Transporter
  • Diffusion

Blood CSF barrier

  • At choroid plexus
    • Choroid plexus capillary endothelial cells
      • Devoid of tight junctions (Unlike other capillaries in the brain) → More permeable to macromolecules
    • Choroid plexus epithelial cells: have tight junctions
      • Trans-epithelial transport of macromolecules regulated by epithelial transporters
  • Formed by modified endothelial cells
  • Different from BBB
  • More leaky than BBB
  • Multi drug resistant pump