The blood-brain barrier (BBB) is a highly sophisticated and intricate physiological mechanism that serves as a protective barrier between the circulatory system and the central nervous system (CNS). It is composed of a network of tightly packed endothelial cells that form a selective permeable barrier within the walls of the capillaries in the brain. The BBB acts as a gatekeeper, regulating the passage of substances from the bloodstream into the brain and spinal cord.
Its main function is to shield and maintain the stability of the neural environment by preventing the entry of harmful agents, such as toxins, pathogens, and large molecules, into the CNS. The BBB achieves this by actively controlling the transport of substances, such as ions, nutrients, and molecules, across its selective membrane. It allows essential molecules like oxygen, glucose, and certain hormones to pass through, while impeding the movement of most larger molecules and cells.
The BBB also plays a crucial role in regulating and maintaining the appropriate chemical composition of the brain's interstitial fluid. It serves as a barrier for potential neurotoxic substances and protects the fragile neurons from the general circulation.
Understanding the blood-brain barrier's structure, function, and regulation is crucial in various medical fields, such as drug delivery, neurology, and neuroscience research. Impairments or dysfunction of the BBB have been linked to numerous neurological disorders and diseases, highlighting its significance in overall brain health and function.
