Cerebrospinal Fluid and Blood-Brain Barrier
Start with the big picture
CSF is actively secreted by the choroid plexus, with sodium transport contributing to its formation. It passes from the lateral ventricles through the third and fourth ventricles into the subarachnoid space, then returns to venous circulation through arachnoid villi. Its roles include cushioning the brain and spinal cord, supporting chemical stability and waste clearance, and providing buoyancy. The BBB is formed by tight junctions between capillary endothelial cells, reinforced by astrocyte foot processes. It permits gases and lipid-soluble substances to cross, while restricting many other substances; glucose crosses via GLUT1 transporters. The topic also introduces hydrocephalus caused by impaired CSF absorption or blocked flow, and conditions associated with BBB dysfunction.
What you'll learn
- Trace the route of CSF circulation from the ventricles to the subarachnoid space and venous circulation.
- Describe how the choroid plexus actively secretes CSF.
- Identify key mechanical and chemical functions of CSF.
- Explain the BBB’s structure and selective permeability, including GLUT1-mediated glucose transport.
- Distinguish impaired CSF absorption from blocked flow as causes of hydrocephalus.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
