Blood-brain barrier
[Ref: KB2:p225]
Blood-brain barrier
Tight junctions between capillary endothelial cells
Blood-CSF barrier
Tight junction between choroid plexus epithelial cells
NB:
- Separated from blood by blood-brain barrier
- Only lipid soluble substance can easily cross
- Glucose passively diffuse across blood-brain barrier
* Faciliated by GLUT1 channels
Substances which cross BBB easily
- O2
- CO2
- Lipid soluble substnces
- Water (though still slower than through normal capillaries)
- Na+
* Also actively transported into CSF in the choroid plexus