Adonis Diaries

Article #35 (Started March 4, 2006)

 “Efficiency of the human body structure”

This article is an on going project to summarize a few capabilities and limitations of man. While the most sophisticated intelligent machines invented by man may contain up to ten thousand elements, the human machine is constituted of up to a million trillion of cells, up to a thousand trillions of neurons in the central nervous system, about a couple hundred bones, and as many organs, muscles, tendons and ligaments.

In the previous article #33 we discussed a graph in a story style and discovered that a human barefoot in texture, shape, and toes has a higher coefficient of friction than many man-made shoes that allow easier traction to move forward for less energy expenditure. We also expanded our story to observe that the structure of the bones and major muscles attached to limbs for movements as lever systems provide higher speed and range of movements at the expense of exorbitant muscular efforts.

A most important knowledge for designing interfaces is a thorough recognition of the capabilities and limitations of the five senses.  One of the assignment involves comparing the various senses within two dozens categories such as: anatomy, physiology, receptor organs, stimulus, sources of energy, wave forms, reaction time, detectable wavelengths and frequencies, practical detection thresholds of signals, muscles, physical pressure, infections and inflammations, disorders and dysfunctions, assessment, diagnostic procedures, corrective measures, effects of age, and safety and risk.

Human dynamic efforts for doing mechanical work is at best 30% efficient because most of the efforts are converted to maintaining static positions in order to preserve stability and equilibrium for all the other concomitant stabilizing joints, bones and muscles.  For example, the stooping position consumes 60% of the efforts for having a work done, in addition to the extremely high moment effected on the edges of the lower back intervertebrae discs.  Static postures constrict the blood vessels and fresh blood is no longer carrying the necessary nutrients to sustain any effort for long duration and heart rate increases dramatically; lactic acid accumulates in the cells and fatigue ensues until the body rests in order to break down that acid.

Human energy efficiency is even worse because most of the energy expended is converted into heat.  Not only physical exercises generate heat but, except for glucose or sugar, most of the nutrients have to undergo chemical transformations to break down the compounds into useful and ready sources of energy, thus generating more heat.  Consequently, heat is produced even when sleeping when the body cells are regenerated. Internal heat could be a blessing in cold environments but a worst case scenario in a hot atmosphere because the cooling mechanism in human is solely confined to sweating off the heat accumulated in the blood stream.  Heat is a source of blessing when we are sick with microbes and bacteria because the latter is killed when the internal body temperature rises above normal.