A friend of mine sent me this link [1]. I am not sure why he sent it to me.
But, the article at the link inspired me to write this blog.
Point:
The article says,
“that if you are of South Asian descent (from India, Pakistan, Sri Lanka,
Bangladesh, Afghanistan, Bhutan, Maldives, or Nepal), you have an
increased risk of developing heart disease, a big unhealthy gut, and type 2
diabetes, regardless of your other risk factors. That’s right—even if
you are a slim, vegetarian, non-smoker with low cholesterol and average blood
pressure, simply being Indian puts you at risk for these conditions.” The
writer further states, “Your metabolism is unique,” and advises good nutrition
and proper exercises.
My summarizing point:
Good
nutrition and exercise are perhaps the best advice for lay people. But, from a
human body research point of view, the material characteristics and physical structure of the tissues,
organs, and systems in the human body should also be investigated. Similar to the
failure mechanisms of any component or system in a physical machine, human
organs and systems also malfunction due to structural and operational
conditions over time. In the case of humans, a research project should look at
structural differences between South Asians, other Asians, and other groups to discover the fundamental contributing factors to health problems.
Detailed Description:
Cardiac blockage, heart
attack, diabetes, and other diseases are the result of organs and tissues in
the human body not functioning properly. There has been a lot of medical
research going on in these fields. That is good and necessary. But, from an
engineer’s point of view, I think fundamental engineering research is also needed.
Heart is a pump that
circulates blood in the body. It is actually a very simple machine. It is a highly flexible
container that has built-in muscles, which squeeze the walls of the container
to change its volume. When the volume is at its highest, blood flows into one
of its chambers. When the volume is smallest, the blood is pushed out. There
are several valves that allow blood to come in and go out in the right
sequence. What are the engineering considerations in the design of such a
machine.
What are the pressures inside
and outside the various walls? When the muscles work on the walls to change the
volume to pump the blood, what is the stress distribution on the walls? Heart
operates in a cyclic manner and hence, one will look at fatigue considerations also.
If an engineer were to design a heart, he would want to calculate the thickness
of the walls of the container, the heart. It has to be thick enough to be
strong but should be thin enough to be flexible as its volume is constantly (periodically) changing. There should be no points that would lead to stress concentration.
What are the characteristics of the material of the tissue that makes up the
walls and other parts of the heart? That is, what is the elastic modulus,
tensile, compressive, and shear strength values of the material of the tissue
that makes up the walls of the heart. Are these values uniform or are they varying
throughout the walls and other areas of the heart?
Blood is actually a mixture
of several chemicals and there may be some gases also dissolved in it.
Compressibility and incompressibility and viscoelasticity of such a fluid would
have an effect on the operation of the heart as a pump. It is also possible
that there is some heat transfer taking place between the fluid (blood), the
walls of the heart, and other surrounding parts of the body.
I will leave a discussion of
the valves in the heart for now.
Blood comes into the heart
and flows in and out through the arteries and veins. Arteries and veins are
highly elastic-plastic pipes. Blood flow through such pipes is actually
harmonic or pulsatile, i.e. it is not steady state. When the heart pushes blood
through one of those pipes, the walls would expand while the blood moves on. At the
next part of the cycle, the pipes collapse to a lower size and perhaps, the cross-sectional shape also changes. These changes
impose stresses on the pipe walls. Of course, the pipes are not hanging loosely
but are supported by other tissues. Thus, the properties of the material of the
tissues of these pipes (blood vessels) will determine the shape of the blood
flow passages. The fluid flow itself depends on the Reynolds numbers of the
flow at various points along the pipes. During its passage, blood is undergoing
chemical reactions with other fluids across the (semipervious) walls, its properties are
changing continually as it flows. Friction factors will determine the hydraulic
resistance to flow and the pressure drops along the path of blood flow and that pressure drop is what the
heart is pumping against. These pipes (arteries, veins, and capillaries) are
not smooth, round, and straight. Thus, there is always a chance for some solid
particles to get stagnant at some locations unless forced by fast currents.
Depending on what a person is doing physically, there is demand for more or
less blood by various organs since blood is simply a transport medium. Blood
plays a role similar to what water plays in a coal slurry transportation
system.
What has all this got to do
with people of different ethnic groups and their problems with their hearts?
It is perhaps true that the
food they consume would influence their heart health and therefore the diseases
they are subjected to. But, have the researchers measured the differences in
the thickness distribution of the heart walls in people of various ethnicities and different food intakes? Have they compared the physical characteristics
(Elastic modulus, Poisson’s ratio) of the tissues that make up the heart and
blood vessels?
Some measurements could be
made on cadavers and results compared. It is perhaps necessary and possible to make
measurements of live tissues during heart surgeries. That may show a need for special
measurement devices such that the measurements are quick and do not interfere
with the critical procedures.
Readers may please note that
this blog is written by a retired engineer and not by one with any medical
knowledge. This blog writer believes that there is need for engineering
modeling of the entire human body.
Reference:
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