Chapter 8
Continuous Blood Pressure Variation:
Hidden Adaptability
Gary D. James
Introduction
There is something very enigmatic about blood pressure. Most people including
most social scientists and human biologists know it to be an important cardiovas-
cular health indicator, something that gets measured in the physician’soffice as part
of an examination. Specific numeric values are determined, and if they are too high,
substantial effort is made to lower them, ostensibly for health reasons. Powerful
drugs that alter basic physiological functions are given to drive down the numbers
to acceptable levels (see James et al. 2013 ). It is written that high blood pressure is
“the silent killer.” Apparently, no one wants death, facilitated by high blood
pressure, to sneak up and surprise them.
So what about these numbers? What are they? Where do they come from and
what do they mean? Are they necessarily something that should concern our every
waking moment? Isn’t blood pressure the focus of natural selection like other
biological phenomena? Shouldn’t blood pressure be something that is adaptive and
not simply a hidden source of mortality? Or can it be both?
Thepressurein blood pressure is a property of theflow of blood plasma as it
circulates through thefinite tubular space of the arterial–venous matrix. It is a result
of the push given blood by the contraction of the heart. Specifically, as the heart
rhythmically contracts, pulses of blood are ejected from it. The force exerted against
the inner walls of blood vessels during the maximum push of the blood pulse is
systolic blood pressure. Diastolic blood pressure is the force exerted against the
inner vessel walls during relaxation and dilatation of the heart, as it refills with
blood prior to its next contraction. It is the minimum pressure of the blood pulse
(James2007a). Arterial blood pressure is thus characterized as two numbers: the
maximum (systolic) and minimum (diastolic) pressure of a pulse wave of blood as it
G.D. James (&)
Department of Anthropology, Binghamton University, Binghamton, NY, USA
e-mail: [email protected]
©Springer International Publishing Switzerland 2016
L.L. Sievert and D.E. Brown (eds.),Biological Measures of Human
Experience across the Lifespan: Making Visible the Invisible,
DOI 10.1007/978-3-319-44103-0_8
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