Blood-brain barrier

Definition

The blood-brain barrier (BBB) is a selective permeability barrier that separates the circulating blood from the brain and extracellular fluid in the central nervous system. It protects the brain from harmful substances while allowing essential nutrients to pass through.

5 Must Know Facts For Your Next Test

1. The BBB consists of endothelial cells with tight junctions, astrocyte end-feet, and pericytes.
2. It prevents pathogens, toxins, and some drugs from entering the brain tissue.
3. Disruption of the BBB can lead to neurological diseases such as multiple sclerosis and meningitis.
4. Certain bacteria and viruses have evolved mechanisms to bypass or disrupt the BBB.
5. Lipid-soluble molecules and gases like oxygen and carbon dioxide can diffuse across the BBB more easily than water-soluble molecules.

Review Questions

• What are the main cellular components that form the blood-brain barrier?
• How does the blood-brain barrier protect the central nervous system from infections?
• Name one neurological disease associated with disruption of the blood-brain barrier.

Related terms

Endothelial Cells: Cells lining blood vessels that contribute to forming tight junctions in the BBB.

Astrocytes: Glial cells in the CNS that support neurons and help maintain the integrity of the BBB.

Meningitis: Inflammation of brain and spinal cord membranes, often caused by infection, which can be facilitated by a compromised BBB.