0 Members and 1 Guest are viewing this topic.
quote:Originally posted by NakedScientistHere's this week's QOTW"WHAT MAKES YOUR JOINTS 'CRACK' FROM TIME TO TIME ?"TNS
quote:Originally posted by gsmollinYea, Neil just can't get no respect. He hits the buzzer first and credit goes to some guy with a "Dr" moniker. Maybe if he put his answer in the form of a question...
quote:Originally posted by NakedScientistANSWER TO LAST WEEK'S QOTW :"WHAT MAKES YOUR JOINTS 'CRACK' FROM TIME TO TIME ?"Dr. Phil has the correct answer. Joints are mobile articulations between bones. The ends of the bones are covered by a slippery layer of cartilage, rather like anatomical teflon, which is lubricated by a thin liquid called synovial fluid. The joint is enclosed by membranes and supporting tissues that retain and maintain the fluid, stabilise the joint, and also help to determine the directions in which it can move.Because the fluid is held within an enclosed space, when the joint moves in certain directions it sometimes squashes the fluid on one side of the joint, and creates a partial vaccuum in the fluid on the other side of the joint.Just as water boils at a lower temperature at the top of a mountain because the atmospheric pressure is lower at altitude, lowering the pressure in joint fluid causes small vapour bubbles to form (from the water in the synovial fluid). When these bubbles then subsequently collapse on themselves again they do so with a 'pop', which is the sound you hear. This process is referred to as 'cavitation', and is responsible for the 'pitting' effect you see on boat propellers and hydrofoils. When the propeller cuts the water it creates zones of low pressure which yield vapour bubbles. The collapse of these bubbles against the propeller surface releases energy which damages the blades.Fortunately for us, it happens too infrequently to cause harm to our joints !TNS