The blood-brain barrier is a selective barrier that separates circulating blood from cerebrospinal fluid of the brain
- It is formed by brain endothelial cells which are connected by tight junctions
- It functions to prevent the movement of large molecules (e.g. bacteria) from the blood into the brain
- Smaller molecules (such as O2, CO2 and hormones) can still freely cross the blood-brain barrier
The purpose of the blood-brain barrier is to protect the brain from most pathogenic infections
- As a result, brain diseases are rare but are also difficult to treat (antibodies cannot cross the blood-brain barrier)
- Diseases that may be associated with the deterioration of the blood-brain barrier include meningitis and MS
The Blood-Brain Barrier
