Friday, July 31, 2015

Soul Searching...

In the two years since I’ve been writing this blog, we’ve explored just about every aspect of our anatomy, from the beautiful intricacies of its form and function to the bizarre ways we modify and even mutilate our bodies. So as this writing endeavor draws to a close and I focus on other projects, I thought I'd end by discussing an aspect of the body that has eluded scientists and philosophers for centuries – the quest for the human soul.

Throughout history, the soul has been part of our search for understanding how the human body works. Ancient terms to describe the soul – from Latin’s anima to the Greek psyche – usually refer to the vital forces within the body, be they motion, movement, or breath. And since the presence of the soul was believed to separate the living from the dead, it seemed only logical that it should reside somewhere in the body. All we had to do was find it.

Some of the earliest references to the soul go back over five thousand years to the Egyptians, who believed the soul was composed of five parts, the most important of which resided within the heart. The heart was believed to be the animating life force, the source of our feelings, thoughts, and will. In fact, the weight of the heart at death determined the soul’s destiny. If the heart was considered too heavy, it would be consumed by a demon, subsequently ending one’s bid for the afterlife. This cardiocentric view of the soul persisted throughout much of history.

Fast forward a few thousand years to the Greek poet Homer, who claimed there were two types of souls. The first, which resided somewhere in the chest, controlled our emotions, everything from joy to reason to rage. The second type of soul was tied to a person’s individual identity and appeared only in dreams. It had no specific location within the body, but served as the animating life force. Homer believed it was this aspect of the soul that fled the body at the time of death.

The foundations of Western philosophy, forged by the likes of Socrates, Aristotle, and Plato, also contemplated the riddles of the soul. Plato considered the soul to be of celestial origin, the immortal essence of a person that was divided into three parts. The rational aspect, which controlled reason, was of primary importance and thus located within the brain. The spirited aspect, responsible for courage, resided in the chest, and the appetitive portion, which governed love (of food, drink, and “loving delights”) was located in the abdomen. The goal of life was to achieve a balance within the soul, especially regarding spirits and appetites; a human struggle that continues to this day.

Plato’s student, Aristotle, stoked his own ideas about the soul. He agreed the soul formed the essence of an individual but, unlike Plato, Aristotle believed the soul could not be separated from the body. So much for its immortality… He too divided the soul into three parts but, in his view, the soul controlled bodily functions and was therefore defined as such: the vegetative function (nourishment and reproduction); the sensitive function (sensation and movement); and the intellectual function (cognition and deliberation). Aristotle also believed that all animals possessed a soul, although the intellectual functions were confined to humans. And like the Egyptians of long ago, Aristotle believed the heart served as keeper.

Early Christians took a broader view. The soul not only gave form to the body, but could be found in every aspect of our anatomy. It was believed the soul entered the body only after the fetus was fully formed. “Delayed ensoulment” coincided with the “quickening,” thus once the mother felt the baby move, the soul was considered to have arrived.

Around the seventh century AD, as the Dark Ages blanketed humanity, the belief in delayed ensoulment persisted. The Roman Catholic Church decreed abortion acceptable as long as it was carried out before the soul arrived, and this was upheld well into the 19th century.

With the blossoming of the Renaissance in the 1300s, Leonardo da Vinci incorporated the search for the soul in his anatomical studies, declaring the middle ventricle of the brain as the most logical spot. René Descartes took up the banner a few hundred years later, agreeing with Leo on the general location of the brain, but claiming the pineal gland was a more likely location.

As scientists learned more about the inner workings of the brain, belief in a craniocentric soul persisted, well into the 20th century. It seemed only natural that the seat of consciousness should also house the soul. But as science advanced and our understanding of the human body crystalized, the soul as animating life force slowly fell away. The mystical realms of life could now be understood in terms of biochemistry, neurology, and genetics, and issues of the soul were gradually relinquished to the theologians.

If you ask me if we possess a soul, I'd have to say I don’t know. The scientist in me embraces the tangible explanations for what constitutes a living body and I’m far more comfortable discussing cellular respiration than arguing the validity of delayed ensoulment.

But that in no way diminishes my fascination with life or the wonder I feel when I contemplate the intricacies of our anatomy. Regardless of our beliefs, we can all agree the human body is a truly astounding machine, one that not only sustains us but enables us to experience our world.

As for the ghost in the machine... I’ll leave that to the theologians.

Thank you so much for reading.

Friday, July 24, 2015

The Fear Factor

If you had to list the things that scare you the most, what would your list include? Human fears run the gamutt, from the insignificant (spiders and heights) to those that haunt us in the wee hours of the night (loss of a loved one, inevitable death). Fear, like other emotions, is a visceral aspect of humanity. But it goes even deeper than that, for fear transcends the boundaries of humanness. It’s part of our evolutionary heritage.

Want to scare a chimp? Place a plastic snake next to an unsuspecting primate (humans included) and you’ll probably witness pure, unadulterated fear. That’s because the fear of snakes appears to be hardwired into many primate brains; a deep-seated phobia that may have evolved to keep us safe. Since many snakes possess the ability to kill, it seems only logical that animals that avoid a close encounter might have an evolutionary edge over the less cautious.

But where does fear reside? And what actually happens when we are scared? Like any emotion, it all begins in the brain.

Many parts of the brain are activated during the fear response. And the majority of them are located deep within; a testament to their ancient origins. Yes, our fancy cortex also plays a role in fear, but the rest of the hardware we share with other animals, since critters lacking fear would stand little chance of surviving in our dangerous world.

Here’s a quick glimpse at the brainy bits responsible for processing fear.

Our sensory cortexes interpret what we see, hear, smell, and feel. The information is whisked to the thalamus, which decides where to shuttle the data, and the hippocampus then places the data in context. The amygdala decodes the data and determines if a threat exists. And if the threat is real, the hypothalamus activates the fight or flight response, which kicks the body into high gear to respond to the situation.

Of course, these reactions happen with lightning speed and, in many cases, the body simply responds as if threatened, even if the threat turns out to be benign. It’s better to gear up than to sit back and contemplate. A momentary hesitation could spell death.

The hypothalamus activates two separate systems when it launches the “fight or flight” response. The sympathetic nervous system activates stress hormones, adrenaline and noradrenaline, which are dumped into the bloodstream. As they circulate, they increase heart rate and blood pressure, which explains the thumping in your chest that accompanies a scary jolt. At the same time, the pituitary gland gets involved by secreting a hormonal cascade that primes the body for action. Pupils dilate (to improve visual acuity), blood vessels in the skin constrict (to shunt blood to the major muscles), and muscles tense for action (which explains the goose bumps). While the essential functions are enhanced, nonessentials, such as digestion and immunity are sidelined. That way, the body can focus on the immediate threat and conserve energy in the process.

But if fear evolved to improve survival, why is it so many of us love a good scare? I admit, I’m an adrenaline junkie, much of which I blame on the years I spent as a firefighter. Once you’ve rushed headlong into a burning building, daily life can seem a bit monotonous, which probably explains my love of rollercoasters, skydiving, and scary movies.

But the reason many of us love a good scare is because the fight-or-flight response involves many neurotransmittersnamely endorphins, dopamine, and serotonin, that are also responsible for a rush of pleasure (think orgasms). That is why a momentary scare is followed by a blissful blast of relief. Once our brain realizes the fear isn’t real, our body can simply enjoy the rush, which is why screaming is often trailed by nervous giggles.

But humans can do something no other animals can: they can conjure fear. Our sophisticated brains enable us to do some amazing things. But they also come at a price, for although we are gifted with imagination, much of our imagining can evoke fear.

Fear of the future, fear of loss, fear for the ones we love… there are a million ways we torment ourselves by conjuring fear. But it is worth noting that, however much we languish in fear, it has little effect on outcome.

So keep your fear in check and save it for life’s true emergencies. The next one could be right around the corner…

Friday, July 17, 2015

Playing Defense

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.

Related Posts

Fecal Foes
From Oral to Anal: A Gastrointestinal Journey
The Unseen

A deep read on the subject:

Friday, July 10, 2015

Fire Down Below

Last week, we took a brief glimpse at the long and convoluted history of prostitution, so I thought it only natural to follow up with an infectious postscript.

For as long as humans have been exchanging bodily fluids, pathogens have been part of the mix. And when it comes to bumping genitals, there are a whole slew of contagions getting in on the action. Because a comprehensive overview is beyond the scope of this blog (not to mention my short attention span), we’ll stick to the highlights while we explore the dark and daunting world of STDs.

First, let’s clarify the terminology. You may have noticed that the term STD has lately been supplanted by STI. What differentiates a sexually transmitted disease from a sexually transmitted infection is the presence of symptoms. However, since some STDs aren't accompanied by symptoms, it’s really splitting hairs. So for the sake of today’s post, we’ll stick to the tried and true acronym, STD.

Sexually transmitted diseases most likely evolved along with humans and historians have been chronicling their presence all the way back to the Bible. The Old Testament refers to “the running issue,” referencing the “clothing needing washing as did the man himself,” most likely referring to gonorrhea, which causes that telltale discharge from the penis. And it wasn’t until the Middle Ages (around AD 1200) that the disease was finally linked to sex.

But gonorrhea is only one of many STDs plaguing humans, for the list of potential pathogens is long and varied.

STDs come in three basic varieties: bacterial (gonorrhea, syphilis, and chlamydia, to name a few); viral (Hepatitis B and C, Herpes, HPV, and HIV); and parasites (such as trichomonas, a pesky protozoan that thrives within urethras and vaginas). And it’s the type of pathogen that determines the treatment.

Since the advent of antibiotics, the bacterial bugs can usually be wiped out with a simple prescription, as can trichomonas. Unfortunately, the viral pests are not so simple. Once a person is infected, herpes and HIV are here to stay, and one can only mitigate the symptoms. Hepatitis, however, forms a mixed bag. With Hepatitis B, most people can be cured, although a minority will become carriers for life. Hep C holds a more dismal future, as a majority will suffer long-term infection with chronic liver disease on the horizon.

But try to imagine what these maladies must have been like before the advent of modern medicine. So to keep things in perspective, let’s peruse some of the ancient treatments that were once believed to cure the “fire down below.”

The ancient Greeks were some of the first to record the treatment of venereal disease. In fact, the term “herpes” originates from the Greek, meaning “to creep or crawl.” And how did they attack the creepy-crawlers? By burning off the lesions using hot irons. Despite their torturous treatments, they get kudos for instituting public policies aimed at reducing the spread of herpes, although their “no public kissing” rules probably did little to curb the virus.

By 1746, London’s Lock Hospital was the first to establish public treatment programs for the infected. And the 18th and 19th centuries saw the use of mercury, arsenic and sulphur as the primary remedies, although these dangerous regimes caused serious side effects, even death. Despite the danger, arsenic, in the form of salvarsan, was used to treat syphilis well into the 20th century.

And as scary as these diseases can be, what scares people even more is the social stigma attached to them. However, for those of you harboring an STD, take heart. You are hardly alone in your affliction. Here are a few statistics to bring it all home.

According to the CDC, there are over three hundred million new cases of STDs in the world each year. The human papillomavirus (HPV) is now the fastest growing STD and nearly all sexually active folks will contract it at some point in life.

About one in five Americans has genital herpes, yet about ninety percent of them don’t know they have it. And health officials warn that by 2025, up to forty percent of men and almost half of all women could be infected with this permanent virus.

And of course, HIV is still rampant, still spreading, and still deadly. As the sun sets in South Africa, another fifteen hundred new infections will have taken place today. Yes, I said fifteen hundred per day. And that’s the conservative end of the statistic.

Let’s face it, STDs are scary, and the emotional toll they incur can be as burdensome as their symptoms. But pathogens, like us, are thriving members of the biome and will forever be a part of life on our planet.

So stay informed, stay healthy and, for god’s sake, use a condom.