October 28, 2005 | David F. Coppedge

Red Blood Cells Are Master Contortionists

Biophysicists have analyzed why red blood cells are able to squeeze through tight spaces on their journeys through our tissues, reports the UCSD Jacobs School of Engineering.  Their membranes contain a network of 33,000 hexagons arranged in a complex geodesic dome formation.  Each hexagon vertex is joined with flexible lines to a central maypole-like proto-filament, giving it the ability to twist and contort without breaking.  This contortionist ability serves another purpose beyond just enabling the cell to get through tight spaces: it also helps squeeze out the oxygen into the tissues.  Despite being twisted, folded, flattened or stretched, the geodesic structure permits the cell to pop back into its familiar biconcave shape.
    The press release states, “Their paper in Annals of Biomedical Engineering uses aeronautical terms commonly used to describe the changing position of an airplane to explain how the six attached spectrin fibers make a proto-filament swivel and flip.”  Science Now took note of this study on “bendable blood.”

The shape of red blood cells is also the optimum for maximizing surface area (for diffusion) without sacrificing volume (for payload).  If they were rigid disks, they would get stuck, starving tissues of oxygen and causing death.  As you work today, think about those little erythrocyte spelunkers making their rounds, delivering the goods from that last breath of air to every cubic micrometer of your body.  The Creator thought of everything.

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Categories: Cell Biology, Human Body

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