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Seven Deadly Sins Sunday: Gluttony Part 3

May 1, ’11 12:01 AM

 

In Part 1 of “Gluttony”, we set up the concept of Seven Deadly Synapses the book.

 

 

In Part 2, we looked at how an Oreo cookie is broken down and ends up either becoming a part of us, or being released in the toilet.

In this Sunday’s installment, we’ll see how chemicals in our brain and even the bacteria that live in our gut drive this process.

Gluttony

Part 3

The brain not only keeps us from suffering social embarrassment from anal leakage, but also has a huge role in determining when, where, and what we eat. If gluttony is a sin, it resides in the brain, not in the automated parts of the gut that lie outside of our control. The brain is a complex organ. There are, scientists estimate, 100 billion nerve cells, about the same number of nerve cells as there are stars in the Milky Way galaxy. Each of these nerve cells makes connections with 10,000 others, on average. To make sense of such a complex organ, it’s convenient to think in terms of levels of organization, and for our purposes, we’ll consider four levels.

Nerve activity in the gut is in waves, which is what moves materials through the gut by peristalsis. Photo: Rolf Hicker http://www.hickerphoto.com/

The intestines form a tube, and all along that tube is a gut nervous system. We saw this earlier when we were talking about peristalsis, the milking action of the bowel. This is a sort of  “housekeeping” function, which occurs to a greater or lesser extent throughout a lifetime. Nerve cells fire in waves, like the ebb and flow of the ocean, and like the ocean the waves can be big or little, or can come in frequently or less frequently, but they’re always there. The gut nervous system, called the enteric nervous system, is influenced by the content of the gut as well. More about this later.

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Seven Deadly Sins Sunday: Gluttony Part 2

Apr 24, ’11 12:01 AM

Each Sunday, I’m excerpting a chapter of The Seven Deadly Synapses, a book on the neuroscience of sin. In this series, we’re examining the sin of Gluttony.

In part 1 of “Gluttony”, we didn’t get to the scientific part. It was mostly just a warm-up. Now it’s time to figure out how the taste system sends a signal to the brain, and how the digestive system handles food.

 

Gluttony

Part 2

For most of mankind’s history, eating has been the key to staying alive and so has been a human’s main job. Most of a person’s waking hours were devoted to getting calories, processing calories into a healthy and digestible form, and storing calories for future needs. The word “famine” appears 107 times in the King James Version of the Christian Bible (including the passage shown here, that describes a famine so severe that a mother boils and eats her son); “hunger” 60 times; “starve”, “starving”, “starvation”, 19 times. Other religious texts show a similar historical fixation with either metaphorical or real hunger: the word is used 74 times in the Qur’an, and only 18 times in the Upanishads. Gluttony is likely to be a sin mostly because it revels in the flaunting of what mankind has struggled so hard, for so many years, to achieve: nutrition.

 

To find food, and eat it, and to balance surfeit with famine, is the responsibility of a few thousand nerve cells in a pinky-end-sized hunk of brain called the hypothalamus. Just like the thermostat in your house keeps the household temperature close to where you want it to be, the hypothalamus is responsible for your body’s balancing acts, the processes and feedback loops that physiologists call “homeostatic mechanisms”. Like Goldilocks, we want our bodies to be “just right”. not too cold, not too hot; not too thin, not too fat; not too much breath, not too little. How the hypothalamus causes us mischief is the root of our story.

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To Sleep, Perchance to Cause a Midair Collision

Apr 18, ’11 8:00 AM

Recent incidents with air traffic controllers have pointed up the hazards of shift work and the supremacy of the circadian rhythm. In one recent case, an air ambulance was forced to land at 2 a.m. without local air traffic controller guidance at Reno-Tahoe International Airport.

These recent incidents have pointed up the existence and causes of what medical science calls Shift Work Sleep Disorder, or SWSD. It’s not clear how many people are affected by SWSD, but it’s probably a fairly significant chunk of the 15% of Americans who perform night-shift work.

Lead (battery) balloon

When I was 19, I dropped out of school for a time and took a job working in a plant that melted down lead plates from car batteries and turned them into lead ingots. The lead ingots were then sold back to AC Delco and other manufacturers of lead-acid batteries.

My job was to maintain the efficiency of the blast furnace by climbing two stories to its top, where there was a small hole about twice the diameter of a pencil. I’d stick a hollow metal rod inside. On the cooler end of the rod was a hand pump and a toy balloon for collecting the gases. Then I’d bring the balloon back to the lab, rushing so that the entire thing didn’t leak, and run the gases through a chromatograph, an instrument that separated the gases by size. I’d report this to the engineers in the morning. These data would tell the engineers, who wore white hardhats, whether the furnace needed more air, or more fuel, to burn efficiently.

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