Synovia (joint fluid) – the fluid which lubricates the joints
In a healthy joint it is the synovia that absorbs shocks and enables movements with as little friction as possible. Besides that, this clear liquid serves as transport agent for nutrients like glucose or amino acids to nourish the joint cartilage. And on the other hand, it disposes of waste products.
Hyaluronic acid is at the same time the most important and quantitatively biggest component of the synovia. At rest, the synovia is of viscous consistency whereas in action it is of a clearly more liquid consistency. The so-called viscoelastic properties depend on the molecular weight of the hyaluronic acid, produced naturally in the body.
As mentioned already, the synovia has two important functions: It reduces friction of the joints when in action and besides that it transports nutrients and oxygen to the joint cartilage.
The component that makes the synovia viscous is the hyaluronan. Firstly, it binds water and turns it into a viscous mass which, if squeezed, is not pressed out of the joint space but stays in place, preventing like this direct contact and thus friction between the two joint surfaces.
Secondly it nourishes the joints cartilage. There are no blood vessels in the joint cartilage that would nourish it. That is why the only means nutrients and oxygen can be transported from the synovia to the cartilage is by diffusion. This in turn is only possible because tissues like cartilage or ligaments have a very slow metabolism and therefore need themselves very little of these nutrients.
To maintain its properties and to fulfil its important functions, the synovia must be renewed constantly. The primary need of nutrients is secured by the connective tissue. Movement is indispensable for the provisioning of the cartilage as it is not connected to the blood circulation. If the supply of nutrients is obstructed, illnesses, inflammations and degeneration of the joints (osteoarthritis) are the possible consequences. Without the help of movement, nutritional supplements cannot get to where they are needed badly.