Parakellulaariset

Parakellulaariset is a Finnish term that translates to "paracellular" in English, referring to the space between cells. In biological contexts, it specifically denotes the pathway that substances take as they move across an epithelium or endothelium, not by passing through the cells themselves (transcellular pathway), but by navigating the junctions between them. This paracellular route is crucial for the transport of ions, water, and small molecules, and its permeability is tightly regulated by specialized protein complexes called tight junctions.

The paracellular pathway's permeability can vary significantly depending on the tissue and its function. For instance, in the intestines, the paracellular pathway allows for the absorption of certain nutrients, while in the kidneys, it plays a role in reabsorption and secretion processes. The integrity of the tight junctions is vital for maintaining barrier function, preventing the uncontrolled passage of harmful substances into deeper tissues. Disruptions to these junctions can lead to increased paracellular permeability, which is implicated in various pathological conditions, including inflammatory bowel disease and certain types of infections. The study of paracellular transport is an active area of research in cell biology and physiology.