Monday 21 January 2013

A is for etymology

In my massively parallel teaching life at The Institute, I spent much of last weekend prepping the Nitrogen Cycle which investigates the wonders of the fact that the major component of the earth's atmosphere Nitrogen is almost inert chemically and so unavailable for most living things.  Several quite distantly related microbes can make a living from reducing N=N to ammonia by using an amazing enzyme called (surprise!) nitrogenase.  But why do we call it Ammonia?  Ammonium salts are highly soluble, so they are only found as crystals in the natural world in places where there's no water - like deserts.  The Romans' richest source for these useful chemicals was near the Temple of Amun in the African province of Libya, so they named sal ammoniacus what we now know as ammonium chloride.
Another part of my brain was simultaneously ploughing through the autonomic nervous system, in which the hormone adrenalin plays a substantive part.  It's called adrenalin because it's produced by the adrenal medulla (the bit on the inside of the adrenal gland).  Where is the adrenal gland?  It's where it says on the tin - ad-renal - on top of the kidney.  And I should know where they are because I spent six months of 1984 dissecting dozens of mouse adrenals out of their fatty matrix to weigh them, but that another day's story.

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