How is synovial fluid produced by the human body?
Synovial fluid is a thick, stringy fluid found in the cavities of synovial joints. With its egg-like consistency (“synovial” partially derives from ovum, Latin for egg), synovial fluid reduces friction between the articular cartilage and other tissues in joints to lubricate and cushion them during movement. The inner membrane of synovial joints is called the synovial membrane and secretes synovial fluid into the joint cavity. This fluid forms a thin layer (roughly 50 μm) at the surface of cartilage and also seeps into microcavities and irregularities in the articular cartilage surface, filling all empty space. The fluid in articular cartilage effectively serves as a synovial fluid reserve. During movement, the synovial fluid held in the cartilage is squeezed out mechanically to maintain a layer of fluid on the cartilage surface (so-called weeping lubrication). Sources: http://en.wikipedia.
Synovial tissue is composed of vascularized connective tissue that lacks a basement membrane. Two cells type (type A and type B) are present: Type B produce synovial fluid. Synovial fluid is made of hyaluronic acid and lubricin, proteinases, and collagenases. Synovial fluid exhibits non-Newtonian flow characteristics. The viscosity coefficient is not a constant, the fluid is not linearly viscous, and its viscosity increases as the shear rate decreases. Normal synovial fluid contains 3-4 mg/ml hyaluronan (hyaluronic acid), a polymer of disaccharides composed of D-glucuronic acid and D-N-acetylglucosamine joined by alternating beta-1,4 and beta-1,3 glycosidic bonds. Hyaluronan is synthesized by the synovial membrane and secreted into the joint cavity to increase the viscosity and elasticity of articular cartilages and lubricate the surfaces between synovium and cartilage. Synovial fluid contains lubricin secreted by synovial cells. It is chiefly responsible for so-called boundary-layer l
It helps to know how joints work. Most, though not all, of the body’s joints are synovial, which means they produce a lubricating fluid that helps the bone ends move past each other easily, without friction. Synovial fluid is produced when the joint moves. But the body is lazy. If there’s no joint movement, there’s no reason to ooze that synovial fluid out into the joint. As time goes on, the body adapts to not creating synovial fluid, and so it takes a lot more movement to get it flowing again. Sources: http://www.dallasnews.com/sharedcontent/dws/fea/healthyliving/fitness/stories/DN-nh_joints_0616gd.ART.State.Edition1.50d243f.
