Blood barrier

Blood Barrier

The blood barrier is a highly selective semipermeable border that separates the circulating blood from the brain and extracellular fluid in the central nervous system (CNS). This barrier is crucial in maintaining the stable environment required for the brain to function optimally.

Structure

The blood barrier is composed of high-density cells restricting passage of substances from the bloodstream much more than endothelial cells in capillaries elsewhere in the body. The barrier is formed by endothelial cells of the capillary wall, astrocyte end-feet ensheathing the capillary, and pericytes embedded in the capillary basement membrane.

Function

The primary function of the blood barrier is to protect the brain from harmful substances that may be present in the blood. It does this by preventing the entry of potentially neurotoxic substances, including certain drugs, into the CNS. The barrier also facilitates the transport of metabolic products out of the brain into the bloodstream.

Clinical significance

Disruption of the blood barrier can lead to a variety of medical conditions. For example, in multiple sclerosis, the barrier becomes permeable to white blood cells, which then cause inflammation and neurodegeneration. In meningitis, bacteria can infiltrate the barrier and cause inflammation of the meninges.

Research

Research into the blood barrier continues to be a significant focus in the fields of neuroscience and medicine. Understanding the precise mechanisms of the barrier's function and how it can be manipulated is crucial for the development of treatments for a range of neurological disorders.

See also

• Blood-brain barrier
• Blood-retinal barrier
• Blood-testis barrier

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