How Does Blood Pressure Work?

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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.

10 Facts About Rosacea

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Rosacea, a skin condition characterized by redness and swelling, is incredibly common: A recent study found that an estimated 300 million people worldwide suffer from it. Here’s what you need to know about the condition.

1. IT HAS A LONG HISTORY.

According to the National Rosacea Society (NRS), rosacea was first described in the 14th century by a French surgeon named Dr. Guy de Chauliac; he called it goutterose (“pink drop” in French) or couperose and noted that it was characterized by “red lesions in the face, particularly on the nose and cheeks.”

2. SCIENTISTS AREN’T SURE WHAT CAUSES IT ...

But they have some theories. According to the NRS, “most experts believe it is a vascular disorder that seems to be related to flushing.” Scientists also think that because rosacea seems to run in families, it might be genetic. Other things—like mites that live on the skin, an intestinal bug called H pylori (common in those who have rosacea), and a reaction to a bacterium called bacillus oleronius—could also play a role in causing the condition. One 2015 study suggested an increased risk among smokers.

3. … BUT SOME PEOPLE ARE MORE LIKELY TO HAVE IT THAN OTHERS.

Though people of all ages and skin tones can get rosacea, fair skinned people between the ages of 30 and 50 with Celtic and Scandinavian ancestry and a family history of rosacea are more likely to develop the condition. Women are more likely to have rosacea than men, though their symptoms tend to be less severe than men’s. But men are more likely to suffer from a rare rosacea side effect known as rhinophyma, which causes the skin of the nose to thicken and become bulbous. It’s commonly—and mistakenly—associated with heavy drinking, but what exactly causes rhinophyma is unclear. According to the NRS, “The swelling that often follows a flushing reaction may, over time, lead to the growth of excess tissue (fibroplasia) around the nose as plasma proteins accumulate when the damaged lymphatic system fails to clear them. Leakage of a substance called blood coagulation factor XIII is also believed to be a potential cause of excess tissue.” Thankfully, those who have rhinophyma have options available for treatment, including surgery and laser therapy.

4. THERE ARE FOUR SUBTYPES.

According to the American Academy of Dermatology (AAD), rosacea “often begins with a tendency to blush or flush more easily than other people.” All rosacea involves redness of some kind (typically on the nose, cheeks, chin, and forehead), but other symptoms allow the condition to be divided into four subtypes: Erythematotelangiectatic rosacea is characterized by persistent redness and sometimes visible blood vessels; Papulopustular rosacea involves swelling and “acne-like breakouts”; Phymatous rosacea is characterized by thick and bumpy skin; and Ocular rosacea involves red eyes (that sometimes burn and itch, or feel like they have sand in them [PDF]), swollen eyelids, and stye-like growths.

5. IT’S NOT THE SAME AS ACNE.

Though rosacea was once considered a form of acne—"acne rosacea" first appeared in medical literature in 1814—today doctors know it’s a different condition altogether. Though there are similarities (like acne, some forms of rosacea are characterized by small, pus-filled bumps) there are key differences: Acne involves blackheads, typically occurs in the teen years, and can appear all over the body; rosacea is a chronic condition that occurs mainly on the face and the chest and typically shows up later in life.

6. YOU CAN FIND IT IN CLASSIC ART AND LITERATURE.

Both Chaucer and Shakespeare likely made references to rosacea. Domenico Ghirlandaio’s 1490 painting An Old Man and His Grandson seems to depict rhinophyma, and some believe that Rembrandt’s 1659 self-portrait shows that the artist had rosacea and rhinophyma.

7. IT MAY BE TRIGGERED BY CERTAIN FOODS AND ACTIVITIES.

According to the National Institutes of Health (NIH) [PDF], people report that everything from the weather to what you eat can cause rosacea to flare up: Heat, cold, sunlight, and wind, strenuous exercise, spicy food, alcohol consumption, menopause, stress, and use of steroids on the skin are all triggers.

8. THERE ARE A NUMBER OF MYTHS ABOUT ROSACEA.

No, it’s not caused by caffeine and coffee (flare ups, if they occur, are due to the heat of your coffee) or by heavy drinking (though alcohol does exacerbate the condition). Rosacea isn’t caused by poor hygiene, and it’s not contagious.

9. THERE ARE SOME PRETTY FAMOUS PEOPLE WITH ROSACEA.

Sophia Bush, Cynthia Nixon, Kristin Chenoweth, Bill Clinton, and Sam Smith all have rosacea. Diana, Princess of Wales had it, too. W.C. Fields had rosacea and rhinophyma, and Andy Warhol may also have suffered from those conditions.

10. IT CAN’T BE CURED—BUT IT CAN BE TREATED.

The NRS reports that “nearly 90 percent of rosacea patients [surveyed by NRS] said this condition had lowered their self-confidence and self-esteem, and 41 percent reported it had caused them to avoid public contact or cancel social engagements.” Dr. Uwe Gieler, a professor of dermatology at the Justus-Liebig-University in Giessen, Germany, and one of the authors of the report Rosacea: Beyond the Visible, said in a press release that "People with rosacea are often judged on their appearance, which impacts them greatly in daily life. If their rosacea is severe, the symptoms are likely to be more significant also, from itching and burning to a permanently red central facial area. However, even people with less severe rosacea report a significant impact on quality of life."

Which makes it all the more unfortunate that there’s not a cure for the condition. Thankfully, though, there are treatments available.

There are no tests that will diagnose rosacea; that’s up to your doctor, who will examine your medical history and go over your symptoms. Doctors advise that those with rosacea pay attention to what triggers flare-ups, which will help them figure out how to treat the condition. Antibiotics might be prescribed; laser therapy might be used. Anyone with rosacea should always wear sunscreen [PDF] and treat their skin very, very gently—don't scrub or exfoliate it. The AAD recommends moisturizing daily and avoiding products that contain things like urea, alcohol, and glycolic and lactic acids.

How Often Should You Poop?

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When it comes to No. 2, plenty of people aren’t really sure what’s normal. Are you supposed to go every day? What if you go 10 times a day? Is that a sign that you’re dying? What about once every three days? Short of asking everyone you know for their personal poop statistics, how do you know how often you’re supposed to hit the head?

Everyone’s system is a little different, and according to experts, regularity is more important than how often you do the deed. Though some lucky people might think of having a bowel movement as an integral part of their morning routine, most people don’t poop every day, as Lifehacker informs us. In fact, if you go anywhere between three times a day and three times a week, you’re within the normal range.

It’s when things change that you need to pay attention. If you typically go twice a day and you suddenly find yourself becoming a once-every-three-days person, something is wrong. The same thing goes if you normally go once every few days but suddenly start running to the toilet every day.

There are a number of factors that can influence how often you go, including your travel schedule, your medications, your exercise routine, your coffee habit, your stress levels, your hangover, and, of course, your diet. (You should be eating at least 25 to 30 grams of fiber a day, a goal that most Americans fall significantly short of.)

If you do experience a sudden change in how often you take a seat on the porcelain throne, you should probably see a doctor. It could be something serious, like celiac disease, cancer, or inflammatory bowel disease. Or perhaps you just need to eat a lot more kale. Only a doctor can tell you.

However, if you do have trouble going, please, don’t spend your whole day sitting on the toilet. It’s terrible for your butt. You shouldn’t spend more than 10 to 15 minutes on the toilet, as one expert told Men’s Health, or you’ll probably give yourself hemorrhoids.

But if you have a steady routine of pooping three times a day, by all means, keep doing what you’re doing. Just maybe get yourself a bidet.

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