Getting at the Heart of Blood Pressure

Fortunately, when nurses take my husband’s or my blood pressure, they simply say it’s good. When the occasional nurse quotes the actual numbers at us instead, we don’t pay much attention. High blood pressure is not among our health concerns. That’s why we don’t know what the numbers mean.

The subject came up today when we visited the doctor’s office. When the nurse left the room, my husband and I shared our profound mutual blood-pressure ignorance, causing me to look the topic up. If you know all too much about blood pressure, first of all, I’m sorry, and secondly, maybe you should move on to another blog, or skip down to the etymology at the end of this post if your expertise doesn’t extend to etymologies.

The top number in a blood pressure reading indicates the force exerted against your arteries when the heart beats. The bottom number shows the pressure between beats. A normal top number is ideally less than 120, and the bottom should be less than 80. Of course, your blood pressure can also go too low, but that’s a rarer problem. These numbers oversimplify because normal numbers vary by age and gender. as this chart shows.

I’m hoping that by looking this subject up one more time and writing about it here I will henceforth remember the normal numbers and their meaning. It seems like something an adult person should know, which is probably what you’re thinking.

As always, though, the words themselves are the interesting part. The top number is called systolic and the bottom is called diastolic. I knew that much but didn’t know the words’ meanings. The Greek root of systolic means “draw together, contract.” That’s your heart beating. As you might guess, diastolic‘s root means “expand, dilate.” That’s your heart at rest, between beats, the chambers filling up with blood to be pumped out with the next beat.

The English majors and poets among you might know that these terms also apply to versification. A systole is a long syllable artificially shortened (i.e., contracted) in order to fit the meter of a line, and a diastole is a short syllable expanded, like your heart at rest, into a long syllable.

Here’s an example of diastole:

I know thee well; a serviceable villain,
— (Shakespeare, King Lear 4.6.251)

The bold type indicates long, or accented, syllables. The “a” in serviceable is a short syllable, as we normally pronounce the word. Shakespeare cheats here by putting it in a spot where he needs a long syllable to fit the iambic rhythm.

I know, I’ve gone too far. You’ve lost interest. Don’t worry about the literary terms. Let your takeaway be that Shakespeare himself wasn’t above cutting corners.