blodhjärnbarriären

Blodhjärnbarriären, known in English as the blood-brain barrier (BBB), is a highly selective semipermeable membrane that separates the circulating blood from the brain's extracellular fluid. This biological barrier is primarily formed by endothelial cells lining the brain's capillaries, which are tightly joined together by complex tight junctions. Astrocytes and pericytes also play crucial roles in maintaining the integrity and function of the barrier.

The primary function of the blodhjärnbarriären is to protect the central nervous system (CNS) from potentially harmful substances circulating in the blood, such as toxins, pathogens, and certain drugs. It also regulates the transport of essential nutrients like glucose, amino acids, and oxygen into the brain while removing metabolic waste products.

The barrier's selective permeability is achieved through various transport mechanisms, including passive diffusion for small, lipophilic molecules; specialized transporter proteins for glucose, amino acids, and other vital nutrients; and receptor-mediated transcytosis for larger molecules like insulin and transferrin.

Disruption of the blodhjärnbarriären has been implicated in numerous neurological diseases, including multiple sclerosis, Alzheimer's disease, and brain infections. Such breaches can lead to increased permeability, allowing potentially neurotoxic substances and immune cells to infiltrate the brain tissue, contributing to inflammation and neuronal damage.

Research into the BBB aims to develop methods for delivering therapeutic agents to the brain more effectively, overcoming the barrier's restrictive nature. Understanding the mechanisms underlying the integrity and permeability of the blood-brain barrier is fundamental for advancing treatments for neurological disorders.