Category Archives: Physiology

BOOK REVIEW: Touch by David J. Linden

Posted on by
1

Touch: The Science of the Sense that Makes Us HumanTouch: The Science of the Sense that Makes Us Human by David J. Linden
My rating: 5 of 5 stars

Amazon page

 

“Touch” is a neuroscientist’s perspective on the human sense of touch, and the profound impact it has on life in our species.

It’s a short book, only about 200 pages of substantive text, arranged into eight chapters. The first chapter considers the role that our sense of touch plays in our lives as social animals. There are a number of studies described in this chapter, but I’ll cite only two that I think give an idea of what the chapter is all about. The first considers why a person holding a cold coffee is likely to be viewed more negatively than if that same person was holding a hot coffee after a handshake. The second reports that survey takers in a mall were more likely to gain compliance if they engaged in gentle, casual, and non-creepy touch—e.g. fingers to forearm.

The second chapter explores the combination of sensors we have in our skin—particularly in our fingers–that allow us to conduct feats of dexterity that (while we take them for granted) are phenomenally difficult. For all the billions put into robotics research, robots are nowhere close to being able to complete tasks that any five-year old can do. The third chapter examines how humans are uniquely geared to be able to give and recognize a particular type of touch sensation, the caress. Throughout the book there are a number of interesting stories, some of them are scientific case studies and others… not so much. This chapter begins with the story of a man on trial for flying into a rage because his girlfriend couldn’t get the pressure right when engaging in manual stimulation. (The author was actually on the jury.)

The fourth chapter delves more deeply and explicitly into sexual contact. Whereas chapter 3, dealt largely with hand against random skin, this chapter deals in genitals and erogenous zones more specifically. There are also a number of fascinating cases / stories herein. A lot of the chapter deals in how we experience and interpret pleasure.

Chapter five explains a specific type of sensation, that of temperature. It considers why crushed chili feels hot but crushed mint feels cool to the skin. While the focus of the book is on human anatomy, physiology, and social interaction, there are many cases from other species throughout the book. This chapter offers a prime example. It explains how Vampire Bats have a unique ability to sense infrared. This is of benefit to them, since they only take blood meals and, therefore, need to be able to sense where the blood is flowing and has the least insulation (fur) over it.

Continuing the examination of specific kinds of sensation, chapter six is about pain. This is where the neuroscientific perspective offers some interesting insight. In particular, because it considers why soldiers who had multiple gun wounds could do their job on the battlefield with nary a peep of complaint, but then would raise holy hell about a bad blood stick a few days later in the hospital. The case of a medic who was badly shot up but not cognizant of it until later is discussed in some detail.

Chapter 7 deals in the itchy, and asks and answers the question of whether or not itchiness is a particular case of low-intensity pain. By low intensity, I’m not speaking of the compulsive behavior sometimes spurred by such sensations.

Chapter 8 is also highly neuroscience influenced. It deals with various illusions of sensation, and how these illusions come about through the interaction of sense and the brain. While the most famous example of such an illusion is phantom limb pain experienced by amputees, Linden addresses less traumatic and more work-a-day tactile illusions for most of the chapter. (This may be because there are a number of popular works of neuroscience that deal in phantom limbs—most notably V.S. Ramachandran’s books.)

I enjoyed this book. It conveys significant technical detail, but does so in a fashion that is easy for a non-expert to follow both because of readable writing and the use of stories. The author uses frequent graphics to help clarify points, and the graphics (mostly line drawings and graphs) do their job by being easy to follow and interpret.

In short, the book was highly readable, concise, and informative. I’d recommend it for anyone interested in the sense of touch.

View all my reviews

BOOK REVIEW: Missing Microbes by Martin J. Blaser, MD

Posted on by
Reply

Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern PlaguesMissing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues by Martin J. Blaser
My rating: 4 of 5 stars

Amazon page

This is one of several popular human biology books of recent years to take note of the fact that your body’s cells are outnumbered 10 to 1 by the bacteria that live in and on you—mostly in your digestive tract—and that our penchant for killing microbes has begun to show signs of harm as well as good. Since the germ theory took hold, we’ve been slaughtering all the little buggers we could, but increasingly we’ve learned that this isn’t without costs. In essence, we’ve been throwing out the baby with the bath water when it comes to our bacteria, while at the same time creating super-bugs.

As a first-worlder who’s been living in the developing world (India), I sometimes get ask if I get sick here a lot or at all. My stock response is to ask the asker whether they have Crohn’s Disease, IBS, Type II diabetes*, or any of the other diseases of affluence seen mostly in the first world. (*Type II diabetes is becoming much more prevalent in the developing world, notably in India where they like their deserts about 9000 times sweeter than, say, a fudge brownie. Furthermore, the disease has disproportionate effects in such countries because of limited treatment availability and late diagnosis.) In many cases, these developed world diseases are being tied to the killing off of our good gut bacteria.

Doctor Blaser’s book focuses on how overuse of antibiotics creates problems. For those who say, “I don’t get no stinkin’ antibiotics when I’m sick. I just suffer it out. Ergo, I don’t need to read this book,” there remain facts of which you should be aware. One such fact is that some of the antibiotics injected into the animals that become our food can act against our own personal microbiome. Yet another is that antibacterial soaps and gels are ubiquitous. Furthermore, the increased popularity of C-sections has starved infants of a source of good bacteria, and made them more prone to certain childhood illnesses.

“Missing Microbes” is organized into 16 chapters. The first discusses many of the “modern plagues” that have come about through the wholesale war on bacteria. The next couple chapters look at the role of microbes on the planet and in our bodies. There is a discussion of increasingly successful pathogens as well as the drugs that came along to take care of them. There is a discussion of over-prescription of antibiotics by dentists and doctors, their use in agriculture, and the transfer of good bacteria from mother to child and how rampant use of C-section negates this transfer. There are a couple of chapters on H. pylori and the lessons learned from trying to eliminate it after it became tied to ulcers. (In one of the most famous stories in modern medicine, a researcher swallowed a beaker of H. pylori to prove his theory to a skeptical audience of physicians.) Asthma is discussed as an example of an illness one might not expect to come about from destroying gut bacteria. One of the effects covered over two chapters is getting bigger (re: fatter as well as taller.) Staving off disease under crowded conditions isn’t the only reason modern agriculture uses antibiotics, it also makes for big, meaty animals—which when eaten by people may make big, meaty (actually, fatty) humans. Blaser then talks about how bad the situation might get (using the term “antibiotic winter,”) before discussing solutions. It’s, of course, true that humanity has gained a lot from antibiotics, and so putting the genie back in the bottle is not a solution. A nuanced approach is called for, and that’s what the author discusses.

I found this book to be informative, and would recommend it to anyone wanting to learn more about the risks presented by overuse of antibiotics.

View all my reviews

BOOK REVIEWS: Gut by Giulia Enders

Posted on by
Reply

Gut: The Inside Story of Our Body's Most Underrated OrganGut: The Inside Story of Our Body’s Most Underrated Organ by Giulia Enders
My rating: 5 of 5 stars

Amazon page

[I recently posted a review of Mary Roach’s GULP. I mention this because that book is likely to be the primary competitor if you’re looking for a tour of the alimentary canal in book form. While I’d recommend both books and point out that the two have different thrusts, if you’re set on reading just one book on poop and farts this year, the two reviews should help you determine which work is more up your alley.]

In this highly readable and humorous book, medical student Giulia Enders teaches us how to poop, what to do when we can’t, how our bodies extract resources from the stuff we shove in our pie holes, and what the bacteria that outnumber our body’s cells by an order of magnitude do for (and against) us. The book is in part a work of popular science, but it’s also a guidebook to the digestive tract. In other words, Enders not only tells readers about the wondrous job their digestive system does, but she also offers advice as to how to keep it running efficiently.

The book is divided into three parts. The first part lays out what the gut consists of and how it does its job. The second part introduces the reader to the enteric nervous system, which is the part of the nervous system that governs the digestive tract and determines when we vomit, poop, and—to some degree–experience emotional turmoil. The final part addresses the body as an ecosystem. The human body consists of 10 trillion cells and another 100 trillion microbes—cells that could theoretically live independently of your body provided the right conditions.

The strength of this book lies in Enders’s ability to put the complex physiological actions of our body into simple, understandable, and whimsical terms. This may mean anthropomorphizing a colon, but so be it—you’ll still get the drift. A prime example is the “Salmonella in Hats” section that equates antibodies with big floppy sombreros that interfere with the germ’s mobility and virulence. The author’s enthusiasm for this “under-rated” organ is infectious.

The book employs amusing, off-beat line drawings to help convey relevant ideas and to support the stories that the author uses to clarify the complex actions of the gut. The art is well matched to the tone of the text, which makes sense given they were drawn by the author’s sister.

As I mentioned in my GULP review, GUT is a very different book despite all they have in common. Enders spends the bulk of her time in the middle of the alimentary canal, where Roach spends most of her time talking about what happens at the two ends. Enders’s book is about the typical Joe’s digestive system, where Roach specializes in extreme cases and narrow (but fascinating) questions. Enders’s book is more of a tour of the digestive system rather than a series of tales of interesting things that happen in and around it. While Roach’s book deals in bizarre cases, Enders’s book is actually more light-hearted and informal in tone. (Whimsical is a good descriptor for GUT.)

I’d recommend this book for anyone who wants to learn more about how their digestive system works and what they can do to keep it working at its best. It’s funny and packed with fun facts.

View all my reviews

BOOK REVIEW: Gulp by Mary Roach

Posted on by
Reply

Gulp: Adventures on the Alimentary CanalGulp: Adventures on the Alimentary Canal by Mary Roach
My rating: 5 of 5 stars

Amazon page

 

This week I’m [improbably] doing two book reviews about works devoted to the human digestive tract. (Before you conclude that I’ve got a colon fetish, let me explain that I was spurred to this research by life events. I did some advanced yoga cleansing practices and wanted to learn more about the science of what was going on down below.) In addition to this book, Mary Roach’s “GULP,” I’ll be soon posting a review of Giulia Enders’s “GUT.” The two books have more in common than their monosyllabic titles beginning in “gu” and the fact that they each came out within the past couple years. They’re both light-hearted romps down your digestive tract. However, they’re also different in several key ways. GULP is quirkier; GUT is perkier, but more importantly the two books have different thrusts (yes, there’s just that much interesting stuff to learn about digestion (and the lack thereof)—which make the two books complementary. Cutting to the chase, I’d recommend both books, but if you only read one book about your alimentary canal this year, I hope my reviews will help you determine which one is for you.

Explaining how Roach’s book is “quirkier” will tell one a lot about Roach’s book and how it differs from Ender’s work. (And since Ender’s writing style could be described as quirky itself, it’ll help clarify that as well.) By “quirky,” I mean that Roach’s book is built around a set of narrow questions that address topics of a bizarre or strange nature. In GULP one will read about whether your pet really wants “paté in beef gravy” [spoiler: it does not], whether the story of Jonah and the whale is BS, how smugglers use their digestive tracts illicitly, what are the benefits of Fletcherizing (chewing your food more thoroughly—much more thoroughly), whether Thanksgiving dinner can split one’s stomach open (like it feels it does), and what’s the worst case flatulence scenario.

This isn’t to say that one doesn’t learn something about the basic science of digestion as one is reading about extreme cases of tasting skill, stomach fistulas, flatulence, constipation, and overeating. One does, but this book isn’t organized to educate one about the alimentary canal systematically and generally. It’s a work of creative nonfiction designed to make the reader keep saying “huh, I never would have thought” and it does an outstanding job of it. You may not have given much thought to some of these topics, but you’ll be craving answers by the time you get past the chapter heading. There’s a reason that Roach’s works top the charts of pop science books. She finds the interesting questions and the most fascinating examples.

There are 17 chapters in GULP, and while they collectively take one on a tour of the alimentary canal, Roach devotes more space to some parts than others. She spends more time on what goes at the head end (smelling, tasting, chewing, and salivating) than does Enders. Also, please don’t think the book is low brow or that it appeals to the lowest common denominator (8-year-old boys?) when I tell you that there are three chapters on various dimensions of flatulence.

As I said, you may not have thought much about some of these questions, but you’ll learn something nonetheless. A prime example can be seen in the chapter on smuggling via the digestive tract. I’d read stories of cocaine mules dying when a condom burst in their stomach, but I had no idea about the extent to which items and materials are smuggled down there. It’s not just drugs. One guy was explaining how he smuggled knives. Really. Knives. Plural.

There are a few topics that are well covered by both books. Take, for example, constipation. Roach elucidates the topic using the case of Elvis Presley and others who’ve been literally terminally constipated. (Ender’s—on the other hand—considers the everyman’s constipation, though with amusing drawings and commentary.)

I’d recommend this book for readers interested in learning more about how their food makes its way through—particularly if you like learning about the strange cases.

View all my reviews