Wednesday, May 16, 2012

Life, Tensegrity, and Thermodynamics

The title of this post is likely to deter most casual readers and appeal to the few ¨nerds¨ out I expect a relatively low number of reads. However, I hope it inspires some analytical thought and stimulates some curiosity. At the very´s interesting! I have to give credit to Mr. Serge Gracovetsky who is a well known researcher (from my home town of Montreal, no less) who has been well ahead of the curve with respect to ¨how the body really works¨. His enormous body of work is something to behold and should be an essential component to any serious clinician´s resource library. His insights and concepts are the essense behind this post...I simply ¨dumb them down¨ for my own consumption. Although the terms Tensegrity and Thermodynamics are quite straightforward, ¨LIFE¨ is a term that is obviously something subject to interpretation...and therefore it is unlikely that a true ¨definition¨ will ever be found. However, in the functional sense, life is the convertion of heat into energy. Living organisms are essentially converters that transform heat into mechanical work. This convertion (heat into mechanical work) is extremely inefficient however...the classic steam engine was only 3% efficient!! This is due to the Second Law of Thermodynamics: Energy continuosly degrades and is less and less available for work. This energy loss is called ENTROPY. Since energy is continuosly lost, entropy increases over time. In order for life to exist (and persist), this energy loss and entropy has to be minimized...therefore ¨life¨ exists in the most energy efficient and low energy cost state (for example, water, salts and minerals crystallize) that is also stable. Gracovetsky states...To survive the animal must minimize its energy needs, that is minimize the rate at which the entropy increases. What does this all mean? Organisms driven purely by muscle would be efficient in a fluid medium (like fish, for example...essentially all muscle and very little solid bone and connective tissue), however in a gravitational field (on the earth) muscles are extremely expensive energy users. Therefore, LIFE has blessed us with Tensegrity...which essentially allows us to be upright in a gravitational field without using muscles all the time. Tensegrity is a technique for building structures by decomposing forces into their compressive and tensile components.
The marvel of tensegral structures is that they are highly adaptable to stress and can therefore support loads without experiencing structural failure. Within the human organism, one of the most prevalent tensile structures is Collagen.
In summary, this simple realization should signal a radical shift in current ¨standards¨ of practice in traditional rehabilitative sciences. It essentially presents a challenge to the conventional, classicla representation and modelling of biomechanical systems (Gracovetsky). Mr. Gracovetsky could not have summarized this very important point more clearly: The response of tissues under stress should not be limited to the mechanical properties of the tissues, but should include the dynamic reconfiguration of the collagen network. Such a desirable analysis is unfortunately not the norm in the literature. ...Hopefully a good read for nerds and non-nerds alike! Cheers!

1 comment:

  1. Thanks for the good definition of tensegrity herein. It cleared things up for me significantly. I appreciate the references to collagen, energy, and the rod man as well. I finally truly get how tensegrity applies to our human body and not just inanimate structural systems.