How Does Blood Pressure Work?

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iStock

Your heart is the master pump for all the blood in your body. With every heartbeat, your heart pushes your blood to all the vital parts of your body, such as muscles and bones, through a network of arteries, capillaries, and veins. As blood flows through the tube-like arteries, it presses up against the walls of the blood vessels with varying degrees of strength. The strength or weakness of this pressure is called your blood pressure (BP).

Each time your heart squeezes, moving your blood to its various destinations, your blood pressure goes up—this number is referred to by a blood pressure reading as systolic. Then, as the heart relaxes after each contraction, your blood pressure goes down; that is called the diastolic reading. Together, these two numbers are presented as a score, systolic over diastolic: Your doctor might tell you that your BP is “120 over 80.”

According to the American Heart Association (AHA), normal blood pressure should reflect systolic pressure between 90 and 120, over a diastolic pressure between 60 and 80. Your doctor may take this measurement with a fancy-named instrument called a sphygmomanometer—an inflatable rubber cuff attached to a manual air pump. When the doctor inflates the cuff at your arm with air, it temporarily cuts off blood flow, and when it releases, the blood starts flowing again, revealing those two key numbers.

Nowadays, though, doctors are recommended to use an automatic blood pressure cuff, which relies on a different method and seems to be more accurate. While the manual cuff relies on auscultation, in which the doctor listens for the correct pressures using a stethoscope/microphone, automatic blood pressure cuffs are usually oscillometric. When blood passes under the cuff, the arm increases in circumference ever so slightly. And by measuring the amplitude of the oscillations (hence oscillometric) at a continuous interval of pressures, blood pressure can be calculated in much the same way.

If you have high blood pressure, a.k.a. hypertension—approximately 130/80 or higher in a person of average health—your heart is working too hard to pump the blood through your body, which becomes dangerous. According to the AHA [PDF], elevated blood pressure is 120–129/less than 80; hypertension stage 1 is 130–139 (systolic) or 80–89 (diastolic); and hypertension stage 2 is 140 or higher (systolic) or 90 or higher (diastolic). If your blood pressure hits 180/120, you're in hypertensive crisis, and you should get help.

If you fall into the above categories, your doctor will recommend changes to diet and exercise and probably medication. High blood pressure is often a precursor to heart disease or a heart attack and can be a side effect of other diseases, such as diabetes. However, your blood pressure can temporarily rise due to stress, pregnancy, and even some common medications, including over-the-counter pain relievers and antidepressants. One high reading will not necessarily mean you have hypertension—but it’s good to keep vigilant.

Editor's note: This story was updated in July 2018 to reflect new blood pressure guidelines from the AHA.

7 Terrifying Historical Remedies for Migraine Headaches

George Marks/Getty Images
George Marks/Getty Images

Migraines are more than just splitting headaches. Migraine symptoms, which affect about one in seven people worldwide, can include throbbing pain on one side of the head, nausea, sensitivity to light and sound, and visual disturbances called auras. Today, several classes of drugs are prescribed to either prevent migraine headaches from happening or halt them once they’ve started. But in previous centuries, migraine treatments weren’t so convenient—or effective.

1. Bloodletting

Whether by scalpel or by leeches, bloodletting was the most common remedy for migraine headaches (and many other ailments) before the advent of modern medicine. Throughout most of history, Western physicians subscribed to the humoral theory, in which human health was governed by four fluids (humors) that must be kept in balance. Sickness was explained as an imbalance of humors, and bloodletting was thought to rebalance the system. The methods varied, though. In the case of migraine headaches, the Greek physician Aretaeus suggested sticking a barbed goose feather up the unfortunate patient’s nose and prodding around until blood flowed.

Even as late as the 18th century, bloodletting was still believed to help migraines. Swiss physician Samuel Auguste Tissot, who was the first to describe migraines as a discrete medical condition in the 1770s, recommended bleeding, better hygiene and diet, and drugs including infusions of orange leaves and valerian.

2. Garlic

The 11th-century physician Abu al-Qasim suggested sticking a clove of garlic into the migraine headache sufferer’s temple. He offered a handy recipe:

“Take a garlic; peel and cut at both extremities. Make an incision with a large scalpel in the temple and keep under the skin a cavity wide enough to introduce the garlic and to conceal it completely. Apply compresses and tighten, let it remain about 15 hours, then remove the device. Extract the garlic, leave the wound for two or three days, then apply cotton soaked in butter until it suppurates.”

Once the wound started oozing—which was considered a good sign—the physician would cauterize the incision with a hot iron. Cauterization was meant to prevent infection, although modern research has shown that it actually lowers the threshold for bacterial infections.

3. Cupping

Cupping—inverting hot glass vessels on the patients’ body—was thought to perform the same function as bloodletting. Prominent Dutch physician Nicolaes Tulp, depicted in Rembrandt’s 1632 painting The Anatomy Lesson of Dr. Nicolaes Tulp, treated a migraine sufferer by cupping. She soon recovered.

A substance called cantharidin, a potent blistering agent secreted by the Meloidae family of beetles, was also applied as part of the cupping and blistering process to draw out bad humors. Unfortunately, if the cantharidin was left on too long, it could be absorbed into the body and cause painful urination, gastrointestinal and renal dysfunction, and organ failure. (Perhaps unrelatedly, cantharidin was also used as an aphrodisiac.)

4. Trepanation

One of the oldest types of surgery, trepanation is the practice of cutting away part of the cranium and exposing brain tissue to treat injuries or chronic conditions like migraine headaches. The 16th-century Dutch physician Petrus Forestus, who meticulously recorded the ailments and treatments of his patients, performed trepanation on a person with incurable migraines. In the brain tissue he found something he called a “black worm.” According to a 2010 study by neurologist Peter J. Koehler, the mass may have been a chronic subdural hematoma—a collection of blood between the surface of the brain and its outermost covering—and a possible cause of the patient’s agony.

5. Dead Moles

Ali ibn Isa al-Kahhal, the leading ophthalmologist of the medieval Muslim world, described more than 130 eye diseases and treatments in his groundbreaking monograph Tadhkirat al-kaḥḥālīn (The Notebook of the Oculists). While his descriptions of ocular anatomy were sound, he also touched on remedies for headaches, and here his prescriptions seem more suspect. To treat migraines, he suggested tying a dead mole to one’s head.

6. Electric Fish

Long before scientists fully understood the principles of electricity, ancient doctors recommended it as a remedy for migraines. Scribonius Largus, the court physician for the Roman emperor Claudius, saw that the torpedo fish—also known as the electric ray, native to the Mediterranean Sea among other areas—had the power to shock anyone who touched it. Largus and other doctors prescribed the shocks as cures for headache, gout, and prolapsed anus.

In the mid-18th century, a Dutch journal reported that the electric eel, found in South America, emitted even stronger shocks than the Mediterranean fish and were used for head pain. One observer wrote that headache sufferers “put one of their hands on their head and the other on the fish, and thereby will be helped immediately, without exception.”

7. Mud Foot-Baths

Compared to expired rodents, warm foot-baths must have sounded positively decadent to those afflicted with extreme pain. Nineteenth-century physicians suggested that migraine sufferers take the waters at Marienbad (now Mariánské Lázně) and Karlsbad (now Karlovy Vary), two spa towns in what is now the Czech Republic. While the mineral waters were useful for alleviating congestive headaches, mud foot-baths were believed to draw blood toward the feet and away from the head, calming the nervous system. “The foot-bath ought not to be taken too hot, and the feet should be rubbed one over the other while washing the mud off, and afterwards with a coarse towel. A brisk walk may be used to keep up the circulation,” suggested Prussian Army physician Apollinaris Victor Jagielski, M.D. in 1873.

Recall Alert: King Arthur Flour Sold at Aldi and Walmart Recalled Due to E. Coli Concerns

iStock/KenWiedemann
iStock/KenWiedemann

A new item has been pulled from supermarket shelves in light of an E. coli outbreak, NBC 12 reports. This time, the product being recalled is King Arthur flour, a popular brand sold at Aldi, Walmart, Target, and other stores nationwide.

The voluntarily product recall, announced by King Arthur Flour, Inc. and the FDA on Thursday, June 13, affects roughly 114,000 bags of unbleached all-purpose flour. The flour is made from wheat from the ADM Milling Company, which has been linked to an ongoing E. coli outbreak in the U.S. Though none of the cases reported so far have been traced back to King Arthur flour, the product is being taken off the market as a precaution.

Five-pound bags of unbleached all-purpose flour from specific lot codes and use-by dates are the only King Arthur products impacted by the recall. If you find King Arthur flour in the grocery store or in your pantry at home, check for this dates and numbers below the nutrition facts to see if it's been recalled.

Best used by 12/07/19 Lot: L18A07C
Best used by 12/08/19 Lots: L18A08A, L18A08B
Best used by 12/14/19 Lots: L18A14A, L18A14B, L18A14C

E. coli contamination is always a risk with flour, which is why raw cookie dough is still unsafe to eat even if it doesn't contain eggs. The CDC warns that even allowing children to play or craft with raw dough isn't a smart idea.

[h/t NBC 12]

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