Last
week, my body came under attack. In an ironic twist following last week’s post
on contagious pathogens, I picked up a nasty bug that for the past seven days has
wreaked havoc on my immune system. Fortunately, whatever I caught was confined
to my northern regions – primarily my throat and chest – rendering me febrile,
voiceless, and with a bone-rattling cough that could give any tubercular a run
for his money.
I’m
happy to report that I am now on the mend, but it got me thinking about the
immune system and the vital role it plays in keeping us safe. Naturally, I
thought I would elucidate its magical machinations, but I found myself
resorting to boring military metaphors traditionally employed for such
discussions. The trusty lymphocytes that serve as armed forces, always on high
alert and ready to mobilize should a foreign invader appear on the horizon. Pathogens, those dangerous usurpers who are just waiting for the opportunity to bust
through our protected borders. Blah, blah, blah.
So
instead of the usual immunity song and dance, I thought we’d explore the more perceptible means of defense, for our bodies have evolved numerous nifty
ways to rid themselves of unwanted guests.
First
and foremost is that largest of organs, the skin, which accounts for around sixteen percent of our body weight. Skin serves as a protective barrier against our
pathogen-infested world and it does this not only through its layered
arrangement, but also by producing specialized peptides that annihilate
microbes and sound the alert when danger approaches.
But
there are two problems when it comes to skin’s defenses. First, skin tears. And
once it is torn – whether through an injury, an insect bite, or on purpose, through surgery, it allows entry to all sorts of dangerous organisms, from bacteria,
to viruses, to parasites.
The
second problem concerns topography: although our skin is one large organ, it
varies from surface to surface, and some of our most vulnerable surfaces are
those that house our mucous membranes. For example, the respiratory tract. The
moist, gooey surfaces of our respiratory system provide the perfect portals for
pathogens. Each time we put a hand to our mouth, pick our nose, or simply take
a breath, we can usher in a suite of infectious organisms that would love to
plant their flag.
Fortunately,
our respiratory tracts have devised a few clever ways of ridding themselves of
pesky pests, which explains why we cough, sneeze, dribble, and blow. Our lungs
also sport a thin layer of microbe-fighting proteins, which defend against
any bugs that manage to weather the snotty storm.
But
pathogens are crafty. Some, like influenza, actually attach themselves to our
bronchial membranes to prevent their quick expulsion. Others, such as measles
and whooping cough, render our cilia inoperable. Those small, hair-like
projections are designed to usher pathogens up, up, and away from our lungs, and
when they are knocked off-line, bugs can simply run rampant.
The
respiratory tract is but one of many portals for pathogens. Our stomachs are
prime targets for many food- and waterborne bugs, which cause a wide range of
misery, illness, and death. Luckily, our stomachs make for fairly acidic
accommodations, with an average pH of about 2 (which you science nerds will
recognize as pretty darn acidic). And just like our respiratory tracts, our
gastrointestinal plumbing has devised a couple of rapid evacuation methods, namely
vomiting and diarrhea.
And
speaking of acidic body parts, let’s not forget the vagina. This acidy little
tube sports a pH of around 4, which is ideal for warding off bacterial and
fungal invaders - not to mention sperm, which explains their desperate
swimming. Not so, our urethras, which is why urinary tract infections are so
common. Especially in women, for not only do our urethras lack defenses, but they
are positioned dangerously close to the anus, which as we all know is a virtual
playground for pathogens.
And
speaking of that other southerly portal… The anus, like the urethra, is also ill-equipped
to ward off infection. And what makes it even more dangerous is that, unlike
the vagina, the anus lacks any natural lubrication. So if you’re going to use it for
recreational purposes, do yourself a favor and lube up. It will prevent tissue
tears, which are great access points for infection. And don’t forget the
condom!
So the
next time you find yourself sneezing, coughing, vomiting, or worse, take a
moment to appreciate the fundamental necessity of such functions and know that
as miserable as these symptoms are, they serve a vital role in the fight
against pathogens.
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