Question

Digestive system

what could be the purpose of cell junctions that fit together like jigsaw pieces? consider that the intestinal muscles are often in motion, creating peristalsis.

Answer 1

Intestinal muscles in presence of digested food encounter peristaltic movement in which these tight junctions helps in prevention of leakage of digested food. It is intestinal permeabilty ;property that facilitate solute and fluid exchange between the lumen and tissue.Epithelial tight junctions (TJs) maintain the intestinal barrier while regulating permeability of ions, nutrients, and water.

Tight junctions are tightly stitched branched strands of virtually impermeable seals between cells. The junction completely encircles each cell, preventing the movement of material between the cell. Tight junctions are characteristic of cells lining the digestive tract, where materials are required to pass through cells (rather than intercellular spaces) to penetrate the bloodstream.The major types of proteins in junctions are the claudins and the occludins ,Junctional adhesion molecule and tricelluin.

The transmembrane proteins create a permselective barrier in the paracellular pathways. The intracellular domains of the transmembrane proteins interact with the intracellular scaffold proteins such as zonula occludens (ZO) proteins, which in turn anchor the transmembrane proteins to the actin cytoskeleton,providing leak free flow of digested food even during motion and peristalsis.