Le Chatelier's Principle revisited

I was chatting about Le Chatelier’s principle with Hubert Matthews at an accu meeting in London yesterday evening. Hubert is a very smart guy and explained to me that losing your boarding card is a nice example, but not necessarily of Le Chatelier’s principle. What did I misunderstand?

Le Chatelier’s principle says "systems tend to oppose their own proper function". I incorrectly read this as a description of a poor system, an unorganized system, a system with no feedback, no control, (you get the idea), a system straying further and further out of balance at the slightest touch. In other words the system opposes its own proper function - but only in the sense that it never really had a chance of functioning properly in the first place! A system likely to die a quick natural death. That was the kind of systems behaviour I was looking for a name for. But I’ll come back to that.

So what is Le Chatelier’s principle really saying? As always an example helps. Every cell in your body requires a constant supply of glucose for energy. If your blood sugar level rises (e.g. after a meal) special cells in your pancreas produce insulin. Insulin causes the liver and muscles convert the extra glucose to glycogen and store it away, helping to reduce blood sugar levels. This is normal functioning. This is proper function. Ok. Now, what Le Chatelier’s Principle says (assuming I've got it right this time) is that your body will oppose this proper function! And your body does indeed start this opposition, and for a very good reason – if the insulin is left unchecked it continues to drain glucose from the blood and your blood sugar level gets too low. So when this happens different special cells in the pancreas start to produce glucagon. The glucagon works in opposition to insulin, causing the liver and muscles to convert the stored glycogen back into glucose thus increasing your blood sugar level.

In a healthy person these mini-systems operate quite properly, just like a thermostat, keeping your blood sugar level safely between fairly strict limits. Not too much (hyperglycemia) and not too little (hypoglycemia). They do this by opposing each other. It reminds me of the Goldilocks Principle. Goldilocks didn’t like the bed too soft or too hard, or the porridge too hot or too cold. Goldilocks knew her own mind.

So what have I learned from this? I’ve learned that I understand Le Chatelier’s Principle a bit better if I reword it ever so slightly to start with the word good. Good is a bit weak but I’m a bit pushed for time so it will do for now.

So what is my boarding card example an example of? Does The Inverse Le Chatelier’s principle apply? If a system does not oppose its own proper function is it more likely to be a poor system? I think there's an element of truth to that. If so we have Le Chatelier’s Principles. There are two of them, in opposition to each other, which somehow feels appropriate!

Good systems tend to oppose their own proper function.
Bad systems tend not to oppose their own proper function.

Thanks Hubert.

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