February 11, 2019 Monday
Bedtime Story
Mechanics of Rouleaux Formation
You through your own life experiences would
know and hence acknowledge that viruses repeatedly with great success infect us
in spite of our great advancements both in personal hygiene and medical science.
Sialic acid seems to be an excellent
molecule to serve as an anchor since it is a highly conserved molecule across
all cells in humans and other mammals.
As do viruses find this molecule useful to
transmit and propagate themselves so does our acute-phase protein fibrinogen to
carry out its role.
Fibrinogen too interacts with the molecules
of sialic acid on the surface of erythrocytes and makes them aggregate in a
very special way unlike the haphazard clunk it forms with platelets in a clot.
Fibrinogen makes the erythrocytes stack
themselves one over the other and such type of stacking of the cells in human
blood is referred to as rouleaux (singular roleau) formation.
This type of stacking of red cells in such
a weird manner is the result of their rather unique shape of oval biconcave
disc which are also rather flexible in nature.
To be more descriptive the shape of the
mammalian erythrocytes are that of a biconcave flattened disc that is depressed
in the center, that in vertical cross section has a dumbbell shape and whose
rim on the edge of the disc has a torus shape.
Torus is a subject of great interest for
mathematicians specializing in topology.
Geometrically a torus is described a
surface of revolution formed by revolving a circle in a 3-D space about an axis
coplanar with a circle.
Quite a tough nut to chew isn’t it?
But nature had learnt to exploit this
peculiar shape hundreds of millions of years ago without actually knowing it or
understanding it by sheer and brute method of millions and billions of series
of blind natural selections.
This flexibility allows these sacs of
hemoglobin (yes, they are virtually empty sacs bereft of nuclei and other
cellular machinery in order to maximize the content of precious hemoglobin) to
get deformed while passing through narrow capillaries.
Such great is their flexibility that these
erythrocytes have the ability to deform and squeeze themselves through the
capillaries that are less than half their diameters and after passing out once
again regain back their discoid shape as soon as the compressive forces are
relieved of.
The erythrocytes are again one of those
biological features that are highly preserved not only among mammals but also
other vertebrates.
During rouleaux formation what happens is
that the convex rim of one erythrocyte snugs cozily over the central concavity
of the flattened disc of another erythrocyte lying over it slightly off-centered.
This reminds me for some reason of the
American Totem Pole.
Stay tuned to the voice of an
average story storytelling chimpanzee or login at http://panarrans.blogspot.com
Good night Mon Ami and my fellow cousin ape.
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Another great educator and a teacher that I am aware of is
Professor Subhashish Chattopadhyay in Bangalore, India.
While I narrate stories, Professor Subhashish an electronic
engineer and a former professor at BARC, does and teaches real mathematics and
physics.
He started the participation of Indian students at the
International Physics Olympiad.
Do visit him here:
All his books can be downloaded for free through this link:
For edutainment and English education of your children, I
recommend this large collection of Halloween Songs for Kids:
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