If winters start to feel colder here, blame vasodilation

From Nov. 12, 2000:

I just survived my first Arizona summer and now I'm freezing. Why am I so cold in what was shirt-sleeve weather in Wisconsin?

An excellent question, madam, and very much the mirror image of a hotweather question we seem to recall having discussed in an earlier Valley 101 class.

We feel your pain. When we first arrived in Arizona, lo these many Novembers ago, we marveled on many winter mornings, as we drove to work in shirtsleeves and with the car windows rolled down, at the many people we saw bundled in overcoats, boots and gloves.

Nowadays, in much the same weather as those first November mornings, we shiver and draw the tattered afghan closer over our bony shoulders and throw another Republic employees conduct manual on the fire.

No, it is not a matter, as people so often say, of your blood thinning out.

When you live in extreme heat, an Arizona summer, for example, your body adapts to the conditions in many ways, including a process that is known as vasodilation.

Vasodilation means that when you are hot, your capillaries, those little, teeny tiny blood vessels you come equipped with, rise closer to the surface of your skin so they can throw off heat more easily and help keep you cool. And when it is cold, they shrink back away from your skin to hold the heat in.

This is not necessarily an overnight experience, but the point is that the longer you live in a really hot or cold climate, the quicker your little teeny tiny capillaries learn how to do this. All this is accomplished without your bidding.

When the weather suddenly switches from really hot to cool, it takes time for your body to readjust and de-vasodilate, if there is such a word. Hence, while at home in Wisconsin you may have found a high of 60 almost balmy, in Phoenix you are shivering.

Each of us have bodies that are used to something else, and we have to vasodilate to adjust to what we are used to.