Download 7 August 2015 - MyokinEast.com

7th August 2015
Port Life
The ins and outs of blood pressure
Making Sense of Medicine
Bob Keller
Coursing throughout your body day in and day out from before you were born until you die is a
magical substance we call blood, about 6 quarts of it. Your heart, beating almost 3 billion times in
your lifetime, pumps your blood through about 60,000 miles of blood vessels making a complete
circuit in a minute or so.
Here’s how it works.
It’s really simple in concept. Your heart has two pairs of pumping chambers, one pair to the right and
one pair to the left.
There are four kinds of vessels that carry your blood. Arteries carry oxygen- and nutrient-rich blood
away from the left side of your heart to the rest of your body. They branch into smaller vessels called
arterioles and finally become the tiny capillaries where oxygen and nutrients are delivered to the cells
that need them, and from where the used blood is returned to the heart in veins.
At the same time, the returning oxygen-depleted blood enters the right side of the heart and is
pumped to your lungs, where the blood acquires new oxygen and is returned to the left side of your
heart for distribution to your body.
What is blood pressure?
Your heart contracts, squeezing blood out into your two main arteries: the aorta, which distributes
blood to the body, and the pulmonary artery, which takes spent blood to your lungs. Your heart then
relaxes, only to repeat the contracting and relaxing about 60 to 70 times per minute in a resting adult.
Each cycle is called a heartbeat.
In measuring blood pressure, one actually measures the pressure in your arteries, and the measure
is of the force being applied to the arterial walls at two different times. The first measure is taken
when the heart beats, the time of greatest force when it squeezes blood out into your arteries. This is
called the systolic pressure, which comes from the Greek word systole, meaning to draw together or
contract. The second measure is taken when the heart relaxes. This is called the diastolic pressure
from the Greek diastole, meaning to dilate.
Blood pressure is measured in millimeters of mercury (mm Hg). What this means is that if you have a
tube that contains the element mercury, which is a liquid metal at room temperature, and you apply a
certain pressure to the base of the tube, then the mercury would rise in the tube a certain number of
millimeters. So, a pressure of 120 means the mercury would rise 120 millimeters in the tube.
If your systolic pressure is 120 mm Hg and the diastolic pressure is 80 mm Hg, then this is usually
written as 120/80, mm Hg being understood.
Incidentally, the unlikely chemical symbol for mercury, Hg, comes from the Latin word hydrargyrus,
liquid silver.
High, low, normal.
Your blood pressure changes from minute to minute depending on what you’re doing, how much fluid
you’ve drunk, how stressed you feel and other factors. To get a consistent reading, you or your doctor
might take it when you are feeling calm, after you have been at rest for a time and when you have not
recently had food or drink. Under these conditions, your blood pressure is likely to be at its lowest.
The American Heart Association considers that the normal adult should have a blood pressure of
120/80 or less. They have, as well, ranges of blood pressure related to how concerned you should be
about your circulatory health. The stages are named using the term hypertension, which simply
means high blood pressure. Interestingly, it can also mean a state of high psychological stress.
Briefly, there are four categories of blood pressure other than normal:
¢ Prehypertension, systolic 120-139 or diastolic 80-89: This is not a problem but needs to be
monitored regularly.
¢ Hypertension 1, systolic 140-159 or diastolic 90-99: At this stage, you should consider letting
your doctor prescribe some blood pressure-lowering medication, and to suggest some lifestyle
changes to lower your blood pressure.
¢ Hypertension 2, systolic 160-179 or diastolic 100+: This is serious business, and if you haven’t
seen your doctor about blood pressure, it’s important now that you do.
¢ Hypertensive crisis, systolic 180+ or diastolic 110+: At this stage, you need emergency
treatment.
Remember that we’re talking about normal resting blood pressure. If you’ve been running or are
temporarily stressed or have consumed a lot of water, then your blood pressure may spike to 170 or
more, and this is not a problem. In fact, one would expect such a result. But if your resting blood
pressure is repeatedly that high, then you need help.
What affects blood pressure?
Simply put, blood pressure is affected by the amount of blood in your system, by how fast your heart
beats and how much blood each beat pumps, and by the resistance to flow in your arteries.
The more blood in your system, called blood volume, the harder your heart and vessels have to work
to move it, and your body has a way of regulating this. Blood volume is determined by the amount of
water and sodium you take in; by the amount excreted by your kidneys; and by the amount lost
through the gastrointestinal tract, lungs and skin. If excessive water and sodium are ingested, then
the kidneys respond by excreting more sodium and water in the urine. Conversely, if there is too little
intake of water and sodium, the kidneys reduce excretion, reserving those substances for the creation
of new blood.
When your heart beats fast, as when you’re running or stressed in other ways, the blood pumped out
of your heart, cardiac output, increases, thus increasing blood pressure in your arteries. Generally,
this is not a problem as long as the stress is short-term, giving way to lower blood output in due
course. However, living or working in situations where the stress is constantly high means that your
entire cardiac and circulatory system is constantly running at peak performance and likely to wear out
sooner than you might like.
The other major factor in blood pressure is the condition of the arteries and veins throughout your
body, and this is where heart and circulatory problems are found frequently. Arteries are naturally
open elastic tubes, meaning they can expand or contract to help regulate blood pressure as your life
circumstances change. As life progresses, however, there are factors that tend to reduce the
elasticity of these vessels and to narrow the passage through them, that lead to a degenerative
condition called hardening of the arteries (atherosclerosis). The early triggers of this process may be
smoking, viruses, chemicals, drugs or others. There may also be deposits called plaque, which
results from accumulation of low-density lipoprotein, as described in my May 1 column on cholesterol.
Although this process seems naturally to accompany aging, one can live in a way to keep blood
pressure under control by encouraging dilation of the vessels, vasodilation. Regular exercise and
losing excess weight are important in vasodilation, as is diet.
Among the best natural vasodilators is nitric oxide, not to be confused with nitrous oxide. And the best
way to encourage nitric oxide production is by eating foods high in nitrates, flavonoids and some
others. Specifically, fish, chicken, eggs, cheese and various nuts are worthy sources of these
substances, as are beets, lettuce, celery, spinach, kale, broccoli and hawthorn. Among fruits,
strawberries and melons are best. But best of all is dark chocolate!
As with other conditions in your body, you are the primary determiner of your blood pressure. You
know that a life high in carbohydrates, a life low in exercise and a life dominated by stress is likely to
lead to hypertension and the dangers that implies.
Bob Keller maintains a holistic practice in Newburyport. He offers medical massage therapy for pain
relief and advice on muscular balance and diet as well as psychological counseling, dream work, and
spiritual direction. He can be reached at 978-465-5111 or [email protected].