Mucopolysaccharides are long chains of sugar molecules more commonly called glycosaminoglycans. Glycosaminoglycans increase the viscosity of bodily fluids by attracting water molecules to their surface, effectively making them slippery. This makes them useful in synovial fluid, the lubricant in certain joints and in the extracellular matrix (the fluid between cells). In the gel-like environment of the extracellular matrix, they enable the movement of nutrients and electrolytes throughout the body and also through the membranes of the cells. The large number of water molecules on their surface also makes mucopolysaccharides perfect components of cartilage and tendons because it gives them resiliency.