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 (CNS).
Characteristics of Blood-Brain Barrier
- Selective Permeability - The BBB allows only certain substances to pass through from the bloodstream into the brain, protecting the brain from poténtially harmful chemicals and pathogens while allowing essential nutrients and gases to enter.
- Tight Junctions - The barrier is formed by endothelial cells of the brain's capillaries, which are tightly joined together by tight junctions. This prevents most substances from leaking between the cells and entering the brain tissue.
- Active Transport Mechanisms - The BBB employs specialized transport systems and receptors to actively transport essential nutrients (like glucose and amino acids) and waste products across the barrier, ensuring proper brain function while maintaining a controlled environment.
