How Does Blood Pressure Work?

iStock
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.

The ChopBox Smart Cutting Board Has a Food Scale, Timer, and Knife Sharper Built Right Into It

ChopBox
ChopBox

When it comes to furnishing your kitchen with all of the appliances necessary to cook night in and night out, you’ll probably find yourself running out of counter space in a hurry. The ChopBox, which is available on Indiegogo and dubs itself “The World’s First Smart Cutting Board,” looks to fix that by cramming a bunch of kitchen necessities right into one cutting board.

In addition to giving you a knife-resistant bamboo surface to slice and dice on, the ChopBox features a built-in digital scale that weighs up to 6.6 pounds of food, a nine-hour kitchen timer, and two knife sharpeners. It also sports a groove on its surface to catch any liquid runoff that may be produced by the food and has a second pull-out cutting board that doubles as a serving tray.

There’s a 254nm UVC light featured on the board, which the company says “is guaranteed to kill 99.99% of germs and bacteria" after a minute of exposure. If you’re more of a traditionalist when it comes to cleanliness, the ChopBox is completely waterproof (but not dishwasher-safe) so you can wash and scrub to your heart’s content without worry. 

According to the company, a single one-hour charge will give you 30 days of battery life, and can be recharged through a Micro USB port.

The ChopBox reached its $10,000 crowdfunding goal just 10 minutes after launching its campaign, but you can still contribute at different tiers. Once it’s officially released, the ChopBox will retail for $200, but you can get one for $100 if you pledge now. You can purchase the ChopBox on Indiegogo here.

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The Right Way to Clean Your Face Mask

Properly cleaning your face mask is important to keep it free of infectious material.
Properly cleaning your face mask is important to keep it free of infectious material.
mikography/iStock via Getty Images

In an effort to slow the transmission of coronavirus in public settings, health officials are advising that people unable to practice social distancing wear a cloth face mask. While not as effective at filtering respiratory droplets as medical-grade masks, cloth masks are still recommended as a practical preventative step.

Like all apparel, masks get dirty. They absorb sweat and germs, and they need to be cleaned. But how?

According to National Geographic, the best way to clean a cloth face mask is to take the same approach as the rest of your laundry—toss it in the washer. Laundry detergent is effective against coronavirus because the pathogen is encased in a layer of oily lipids and proteins. Detergents and hand soaps contain surfactants, which reduce the surface tension of the fatty layer. The surfactant molecule is attracted to oil and grease on one end and water on the other. The end that disrupts the oil bursts the coronavirus envelope apart. Tiny pods of surfactant called micelles trap and wash the remnants away. It’s this activity, not the water temperature, that kills the virus, though using a higher dryer temperature can destroy most microorganisms that might be lingering.

Bear in mind there’s a recommended way to take off your mask. Make sure your hands are clean, then pull it off using the straps behind your ears. This avoids contaminating the mask—and your face—with any pathogens that might be on your hands.

Medical-grade masks are trickier, as they’re intended to be used only once and can’t stand up to a wash cycle. If you have an N95 or paper mask, you can set it aside for several days, at which point the virus is likely to become inactive. But keep in mind that health officials still aren’t entirely sure how long coronavirus can persist on surfaces, and it’s possible for a mask to collect particles over time, increasing the viral load.

But what about the rest of your clothes? Experts say not to worry so much about disrobing the minute you get home. The coronavirus likes moisture and dries out quickly on fabrics. You need to be careful with the material covering your face, but the rest of your outfit can wait until your regularly scheduled laundry appointment.

[h/t National Geographic]