Why Doctors Check Your Blood Pressure
By Howard J. Bennett
Depending on your age, there are different things to worry about when you have a checkup. Little kids worry about shots and blood tests. Teenagers worry about having to do something embarrassing like getting undressed or peeing in a cup. Parents worry about whether the doctor will be on time or keep them waiting for hours. Few people worry about having their blood pressure taken.
Although taking your blood pressure does not involve poking you with a needle, it may hurt a little when the nurse inflates the blood pressure cuff on your arm. The cuff has to tightly squeeze your blood vessels to find out what your blood pressure is.
But what is blood pressure, and why do doctors check it?
Not all life forms have hearts or blood. One-celled organisms like amoeba exchange oxygen, nutrients and waste products through cell membranes. Simple multicellular organisms like flat worms accomplish this task via the skin. But as life forms become more complicated, a specialized system is required. The heart and circulatory system evolved for just this purpose.
The heart is divided into two halves. Blood rich in oxygen is pumped from the left ventricle to the body through the arteries. When this blood reaches the tiniest blood vessels called capillaries, nutrients and oxygen are released to the cells and carbon dioxide and other waste products are picked up. This blood returns to the right side of your heart through the veins. The blood is then pumped to the lungs from the right ventricle to eliminate the carbon dioxide and absorb more oxygen. Oxygen-rich blood returns to the left side of the heart for its next cycle through the body. (Other waste products are filtered by the kidney, which is a good thing because it would be a real drag if pee and carbon dioxide were removed by the same organ.)
It takes a lot of power to pump blood through the body. Every time your ventricles contract, they generate a lot of pressure. The right ventricle produces less force than the left ventricle because it takes less power to push blood through the lungs than the rest of the body.
When ventricles pump blood, arteries expand under the pressure. An instant later, the muscular wall in the arteries causes them to contract (squeeze), which helps push the blood along on its journey. There are thousands of miles of blood vessels that wind their way through your body.
You can feel your blood pressure working by checking your pulse. The best way to do this is to gently place the tips of your fingers on your wrist just inside the radius. (The radius is the forearm bone that is closest to your thumb.) When you feel something tapping against your fingers, you have found your pulse.
Although the human body is amazing, diseases have a way of sneaking up on us. One of them is called hypertension (high blood pressure). The condition is rare in kids, but doctors occasionally check your blood pressure to make sure you don’t have it.
Bonus Fact: The scientific name for blood pressure cuff is sphygmomanometer (sfig-mo-ma-nom-e-ter). This is one of the hardest medical words to pronounce. Even doctors have trouble doing it.
© 2012 Howard J. Bennett. All Rights Reserved.
(First published in the Washington Post 3/6/11.)
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