Questionable Content

I ask a lot of questions. I get curious about things I don’t understand and, fortunately or unfortunately, I don’t understand a lot of things around me. Sometimes I get lucky and I’m surrounded by people who can answer my questions. (For instance, last night at Sprout, I had, “How does a chop saw work?” and “What is polynomial time?” and “What is in this delicious soup?” answered quite satisfactorily.) Sometimes people don’t know and just shrug. It is in these moments of great need that I turn to google.

Since it’s so easy to find answers via google, I usually process the information and then never bring it up again, but you know, frequently these questions are really interesting, so I thought I would try my hand at blogging the answers occasionally.

So here’s a first go. Behind the cut are answers to:

1) Why does “nature abhor a vacuum”?

2) Why does giving someone a shot of adrenaline to the heart after an overdose revive them, a la Pulp Fiction?

3) Can one’s eyes be literally bigger than one’s stomach?

4) Why does it feel good to scratch an itch?

5) What’s so funny about peace, love and understanding?

1) Why does “nature abhor a vacuum”?

It turns out nature doesn’t. Apparently, back in ancient times, people believed that vacuums were impossible to create, a philosophical rather than empirical position. There were religious debates on the topic of horror vacui, with the Bishops of Paris declaring that God can do anything, so he can certainly create a vacuum if he wants. During the Renaissance, experimenters showed that vacuums can, in fact, occur. Take a container with a closed body and a spout along the side like a tea kettle. Fill it all the way up with water, then pour some of the water out, taking care that the water line inside the container stays higher than the opening of the spout, so that only water is passing through the spout. You’ll find, when you’ve done this, that an empty space opens up at the top of the container where the water once was. It’s not a perfect vacuum - no such thing as a perfect vacuum has yet to be created - but nothing in life is perfect, is it?

This experiment was also the basis of the creation of the barometer, as well as some truly fun demonstrations, such as von Guericke’s showing teams of horses couldn’t separate two hemispheres stuck together by a vacuum created between them.

In conclusion: nature doesn’t abhor vacuums, it simply dislikes them.

2) Why does giving someone a shot of adrenaline to the heart after an overdose revive them, a la Pulp Fiction?

You will probably not be surprised to learn that the Pulp Fiction scene contains a small kernel of truth manhandled into something much more dramatic. Adrenaline is sometimes used on a person whoe gone into cardiac arrest, however it does not work instantaneously - the adrenaline “re-starts” the heart, it doesn’t immediately counterract the effects of oxygen loss on the brain nor would it flush drugs from your system. That being said, you won’t find paramedics stabbing through people’s breastplates. (Um, where do you keep your heart? I keep mine below my ribs.) “Intracardiac” injection, as it’s called, is seen as risky and unnecessary. Intramuscular injection will, in nearly all cases, serve just fine.

So, with all those caveats and qualifications, it does work. How? Adrenaline - also known as epinephrine - binds to receptors on the walls of your blood vessels. At low levels, it causes vasodilation: the expansion of the vessels, lowering blood pressure. At higher levels, it causes vasoconstriction: the contraction of the vessesls, raising blood pressure. High blood pressure helps circulate more oxygen around the body. More importantly, adrenaline acts on the heart itself, binding to muscle there and increasing the frequency and strength of contractions.

Your body does all this naturally when you confront stressful situations such as traffic jams or bears. But if your heart’s stopped beating, your adrenal gland isn’t always up to the task of reviving it, which is why synthetic adrenaline is sometimes supplied.

The epi-pen an allergy-prone person carries around with them functions in the same way. Anaphylactic shock causes vasodilation - a widening of blood vessels, the opposite of vasoconstriction - so injecting adrenaline will bring blood pressure back to a healthy level and help ensure that the circulatory system stays online.

In both of these cases, administering adrenaline doesn’t “solve” the underlying problem so much as quickly and effectively treat the most dangerous symptom of that problem.

3) Can one’s eyes be literally bigger than one’s stomach?

To answer this question, we need to figure out just how small the stomach can get. The stomach is a flexible organ which can expand to hold about as much food as your grandmother can serve you. Apparently the average, empty stomach has a volume of 45 ml (full, it can hold nearly 50 times as much). The eye, on the other hand, has a volume of 6.5 ml. So the answer to this question appears to be no.

But not so fast! Gastric bypass surgery reduces the amount of “usable” stomach, creating a new, smaller pouch of about 15-30 ml. If we take the lower bound there, the stomach would be only a little over twice the size of an eyeball - and since most of us have two eyes, we can say that such a person’s eyes would be, if not bigger, roughly equivalent to their stomach.

(Of course, if we were tarsiers, our eyes would naturally be bigger than our stomachs, and we wouldn’t have to engage in such gymnastics. We could, though. ‘Cause we’d be tarsiers.)

4) Why does it feel good to scratch an itch?

This question came to me after a blissful afternoon sitting on a Venetian canal eating getlato. One of the lesser species of the planet had helped themselves to my legs (at least they left the gelato for me!) and I was struggling to override the primordial urge to scratch. Sadly, my executive function must be underdeveloped, because I was not very successful. As I looked at the newly-inflammed bites, I wondered - why does something so bad for you feel so good?

I found this New Yorker article, which is incredibly informative, although also quite terrifying (it describes a woman with an unrelievable itch who scratched through the skin of her scalp, through her skull, to her brain). They guess why scratching feels good to us:

Scientists believe that itch, and the accompanying scratch reflex, evolved in order to protect us from insects and clinging plant toxins… The theory goes a long way toward explaining why itch is so exquisitely tuned. You can spend all day without noticing the feel of your shirt collar on your neck, and yet a single stray thread poking out, or a louse’s fine legs brushing by, can set you scratching furiously.

And explain how:

Unlike, say, the nerve fibres for pain, each of which covers a millimetre-size territory, a single itch fibre can pick up an itchy sensation more than three inches away. The fibres also turned out to have extraordinarily low conduction speeds, which explained why itchiness is so slow to build and so slow to subside… Itch, it turns out, is indeed inseparable from the desire to scratch. It can be triggered chemically (by the saliva injected when a mosquito bites, say) or mechanically (from the mosquito’s legs, even before it bites). The itch-scratch reflex activates higher levels of your brain than the spinal-cord-level reflex that makes you pull your hand away from a flame. Brain scans also show that scratching diminishes activity in brain areas associated with unpleasant sensations.

Sounds like a good explanation to me! Hopefully new evidence won’t make us have to scratch it.

*ducks*

5) What’s so funny about peace, love and understanding?