Kansas School Naturalist

THE MODERN MUSCLE MISCONCEPTION–A CASE FOR REALITY

Examine any current biology or anatomy text's explanation of how muscle cells work. All muscle cells contract and relax; none forcibly expand. To restore a body shape or position requires the contraction of opposing muscles, extensors, to stretch out the relaxed flexors. This is the current party line. It is embarrassing that generations of students have dutifully copied this dogma in notebooks and regurgitated it on tests without stopping to ask “Wait a minute teacher; then how can a boneless heart that lacks flexors and extensors expand?” Now if your text addresses this question, the standard answer is that blood pressure in veins re-inflates the heart. Yet any biology student who has dissected a beating frog heart knows it keeps on beating after it is empty. The textbooks are currently inadequate or outright wrong in their explanation of heart expansion, sticking out your tongue, or the movement of elephant trunks and squid tentacles. Yet the error is only apparent to those students with direct experience with hearts and these other structures.

The actual mechanisms for expansion are “hydrostats,” muscle cells running crosswise that squeeze and elongate the relaxed muscle cells (March 26, 1988, Science News 133:204-250). Any good biologist and any good biology teacher would kick themselves, “Why didn’t I question that?” Yet you would only have had reason to question the current view if you had the real experiences; otherwise the standard explanation would never be challenged.

THE TEXT AND THE LAB

Grab a biology book from the early 1950s and try to find three consecutive pages that you could teach today without adding serious revisions or qualifications. Of course it is not possible. Our understanding has greatly advanced; new terms have replaced old to indicate new associations and functions. All abstract media, from computer simulations to photographs to models, function to elaborate the textbook. When the textbook must be revised, many of these abstractions will have to be changed as well. But the real lab work, in 1950 or today or in the year 2010, will not change. The fruit flies, the animal dissections, the myriad experiments, the human body, will all have the right answers in them "for the looking." We know from the work of mathematicians Godel and Turing that no model can prove itself complete. "Whatever kind of machine a rabbit's eye is, it is ultimately different from any simulator we can make." (Schrock, 1983). The real world has to remain the ultimate touchstone in science.

As an added benefit, the structures and processes we experience in the natural world provide us with metaphors which help us build better images for other natural phenomena.