Eleväisvirtaus

Eleväisvirtaus, also known as the blood-brain barrier (BBB), is a selective barrier that separates the circulating blood from the brain extracellular fluid. It is composed of brain capillary endothelial cells, pericytes, and astrocytes, which work together to regulate the exchange of substances between the blood and the brain. The BBB is crucial for maintaining the brain's homeostasis by preventing the entry of harmful substances and allowing the passage of essential nutrients and signaling molecules.

The BBB is formed during the development of the brain and is maintained throughout life. It is highly permeable to small, lipophilic molecules and gases, such as oxygen and carbon dioxide, but restricts the passage of larger, hydrophilic molecules and proteins. This selective permeability is achieved through the tight junctions between endothelial cells, which form a continuous barrier, and the presence of transport proteins and receptors on the endothelial cells.

The BBB plays a vital role in protecting the brain from various toxins, pathogens, and immune cells. It also helps to maintain the brain's unique environment by regulating the concentration of ions, neurotransmitters, and other signaling molecules. Dysfunction of the BBB has been implicated in various neurological disorders, including stroke, traumatic brain injury, and neurodegenerative diseases.

The BBB can be disrupted by various factors, such as inflammation, infection, and certain medications. This disruption can lead to the entry of harmful substances into the brain, causing tissue damage and contributing to the development of neurological disorders. Understanding the mechanisms underlying the BBB and its regulation is essential for developing new therapies for neurological diseases and improving our knowledge of brain function.