CLOSE
iStock
iStock

7 Sanguine Facts About Human Blood

iStock
iStock

The human body is an amazing thing. For each one of us, it’s the most intimate object we know. And yet most of us don’t know enough about it: its features, functions, quirks, and mysteries. That’s why we’re launching a new series called The Body, which will explore human anatomy, part by part. Think of it as a mini digital encyclopedia with a dose of wow.
 

Everyone knows that when you get cut, you bleed—a result of the constant movement of blood through our bodies. But do you know all of the functions the circulatory system actually performs? Here are some surprising facts about human blood—and a few cringe-worthy theories that preceded the modern scientific understanding of this vital fluid.

1. FROM HIPPOCRATES' HUMORS TO BLOODLETTING AND LEECHES

Long before we had scientific proof of the importance of the circulation system, ancient people knew it was important to health. That may be one reason for bloodletting, the practice of cutting people to “cure” everything from cancer to infections to mental illness. For the better part of two millennia, it persisted as one of the most common medical procedures.

Hippocrates, for example, believed that illness was caused by an imbalance of four “humors”—blood, phlegm, black bile, and yellow bile. For centuries, doctors believed balance could be restored by removing excess blood, often by bloodletting or leeches. It didn’t always go so well. George Washington, for example, died soon after his physician treated a sore throat with bloodletting and a series of other agonizing procedures.

By the mid 19th century, bloodletting was on its way out. That said, it hasn’t completely disappeared. Bloodletting has actually been proven an effective treatment for some rare conditions like hemochromatosis, an excess of iron in the body that can lead to liver disease and heart problems.

Today leeches have also made a comeback in medicine. We now know that leech saliva contains substances with anti-inflammatory, antibiotic, and anesthetic properties. It also contains hirudin, an enzyme that prevents clotting. This lets more oxygenated blood into the wound, reducing swelling and helping to rebuild tiny blood vessels so that it can heal faster. That’s why leeches are still sometimes used in treating certain circulatory diseases, arthritis, skin grafting, and reattaching fingers and toes. (By the way, it turns out that even the blood-sucking variety of leech is not all that interested in human blood, contrary to popular belief.)

2. SCIENTISTS DIDN'T DISCOVER HOW BLOOD CIRCULATION ACTUALLY WORKED TILL THE 17TH CENTURY.

William Harvey, an English physician, is generally credited with discovering and demonstrating the mechanics of circulation, though his work developed out of the cumulative body of research on the subject over centuries.

The prevailing theory in Harvey’s time was that the lungs, not the heart, moved blood through the body. In part by dissecting living animals and studying their still-beating hearts, Harvey was able to describe how the heart pumped blood through the body and how blood returned to the heart. He also showed how valves in veins helped control the flow of blood through the body. Harvey was ridiculed by many of his contemporaries, but his theories were ultimately vindicated.

3. BLOOD TYPES WERE ONLY DISCOVERED IN THE EARLY 20TH CENTURY.

Austrian physician Karl Landsteiner first discovered different blood groups in 1901, after he noticed that blood mixed from people with different types would clot. His subsequent research classified types A, B and O. (Later research identified an additional type, AB). Blood types are differentiated by the kinds of antigens—molecules that provoke an immune system reaction—that attach to red blood cells.

People with Type A blood have only A antigens attached to their red cells but have B antigens in their plasma. In those with Type B blood, the location of the antigens is reversed. Type O blood has neither A nor B antigens on red cells, but both are present in the plasma. And finally, Type AB has both A and B antigens on red cells but neither in plasma. But wait, there’s more! When a third antigen, called the Rh factor, is present, the blood type is classified as positive. When Rh factor is absent, the blood type is negative. Got it?

Scientists still don’t understand why humans have different blood types, but knowing yours is important: Some people have life-threatening reactions if they receive a blood type during a transfusion that doesn’t “mix” with their own. Before researchers developed reliable ways to detect blood types, that tended to turn out badly for people receiving an incompatible human (or animal!) blood transfusion.

4. BLOOD MAKES UP ABOUT 8 PERCENT OF OUR TOTAL BODY WEIGHT.

Adult bodies contain about 5 liters (5.30 quarts) of blood (except pregnant women, whose bodies can produce about 50 percent more blood in order to nourish their fetus.)

Plasma, the liquid portion of our blood, accounts for about 3 liters. It carries red and white blood cells and platelets, which deliver oxygen to our cells, fight disease, and repair damaged vessels. These are joined by electrolytes, antibodies, vitamins, proteins, and other nutrients required to nourish all the other cells in the body.

5. THE LIFE SPAN OF A HEALTHY RED BLOOD CELL IS ONLY ABOUT 120 DAYS.

Red blood cells contain an important protein called hemoglobin that delivers oxygen to all the other cells in our bodies. It also carries carbon dioxide from those cells back to the lungs.

Red blood cells are produced in our bone marrow. But not everyone produces the healthy ones. Sufferers of sickle cell anemia, a hereditary condition, develop malformed red blood cells that can’t move easily through blood vessels. These blood cells last only 10 to 20 days, which leads to a chronic shortage of red blood cells, often causing to pain, infection, and organ damage.

6. BLOOD COULD POTENTIALLY PLAY A ROLE IN TREATING ALZHEIMER'S.

In 2014, research led by Stanford University scientists found that injecting the plasma of young mice into older mice improved memory and learning. Their findings follow years of experiments in which scientists surgically joined the circulatory systems of old and young mice to test whether young blood could reverse signs of aging. Those results showed rejuvenating effects of a particular blood protein on the organs of older mice, as well as muscle stem cells.

The Stanford team’s findings that young blood had positive effects on mouse memory and learning sparked intense interest in whether it could eventually lead to new treatments for Alzheimer’s disease. The scientist who led the research is now testing the effects of young plasma on Alzheimer’s patients.

And in August, a California start-up announced it would conduct a clinical trial with volunteers 35 and older to see if a young (human) plasma injection offered anti-aging benefits. That trial is proving controversial, however, because of the price tag: The company will charge patients $8000 to participate.

7. AFRAID OF BLOOD? THERE'S A DIAGNOSIS FOR THAT.

If you’ve cringed your way through this list, you’re not alone—many are a bit squeamish about blood. But for 3 to 4 percent of people, squeamishness associated with blood, injury, or invasive medical procedures like injections rises to the level of a true phobia. It’s called blood injury injection phobia (BII). And most sufferers share a common reaction: fainting.

Most phobias cause an increase in heart rate and blood pressure, and often muscle tension, shakes, and sweating. This is part of the body’s sympathetic nervous system’s “fight or flight” response. But sufferers of BII experience an added symptom: after initially increasing, their blood pressure and heart rate will abruptly drop.

This reaction is caused by the vagus nerve, which works to keep a steady heart rate, among other things. But the vagus nerve sometimes overdoes it, pushing blood pressure and heart rate too low. (You may have experienced this phenomenon if you’ve ever felt faint while hungry, dehydrated, startled, or standing up too fast.) For BII sufferers, this so-called vasovagal response can happen at the mere sight or suggestion of blood, needles, or bodily injury, making even a routine medical or dental checkup cause for dread and embarrassment.

nextArticle.image_alt|e
iStock
arrow
science
Scientists Accidentally Make Plastic-Eating Bacteria Even More Efficient
iStock
iStock

In 2016, Japanese researchers discovered a type of bacteria that eats non-biodegradable plastic. The organism, named Ideonella sakaiensis, can break down a thumbnail-sized flake of polyethylene terephthalate (PET), the type of plastic used for beverage bottles, in just six weeks. Now, The Guardian reports that an international team of scientists has engineered a mutant version of the plastic-munching bacteria that's 20 percent more efficient.

Researchers from the U.S. Department of Energy's National Renewable Energy Laboratory and the University of Portsmouth in the UK didn't originally set out to produce a super-powered version of the bacteria. Rather, they just wanted a better understanding of how it evolved. PET started appearing in landfills only within the last 80 years, which means that I. sakaiensis must have evolved very recently.

The microbe uses an enzyme called PETase to break down the plastic it consumes. The structure of the enzyme is similar to the one used by some bacteria to digest cutin, a natural protective coating that grows on plants. As the scientists write in their study published in the journal Proceedings of the National Academy of Sciences, they hoped to get a clearer picture of how the new mechanism evolved by tweaking the enzyme in the lab.

What they got instead was a mutant enzyme that degrades plastic even faster than the naturally occurring one. The improvement isn't especially dramatic—the enzyme still takes a few days to start the digestion process—but it shows that I. sakaiensis holds even more potential than previously expected.

"What we've learned is that PETase is not yet fully optimized to degrade PET—and now that we've shown this, it's time to apply the tools of protein engineering and evolution to continue to improve it," study coauthor Gregg Beckham said in a press statement.

The planet's plastic problem is only growing worse. According to a study published in 2017, humans have produced a total of 9 billion tons of plastic in less than a century. Of that number, only 9 percent of it is recycled, 12 percent is incinerated, and 79 percent is sent to landfills. By 2050, scientists predict that we'll have created 13 billion tons of plastic waste.

When left alone, PET takes centuries to break down, but the plastic-eating microbes could be the key to ridding it from the environment in a quick and safe way. The researchers believe that PETase could be turned into super-fast enzymes that thrives in extreme temperatures where plastic softens and become easier to break down. They've already filed a patent for the first mutant version of the enzyme.

[h/t The Guardian]

nextArticle.image_alt|e
Robin Stott, via Flickr // CC BY-SA 2.0
arrow
science
15 Overlooked Facts about Rosalind Franklin
Robin Stott, via Flickr // CC BY-SA 2.0
Robin Stott, via Flickr // CC BY-SA 2.0

Today is the 60th anniversary of the death of English chemist Rosalind Franklin, a brilliant and dedicated scientist best known for the honor denied her: the 1962 Nobel Prize for discovering the structure of DNA. Here are 15 facts about her.

1. SHE KNEW HER CALLING EARLY, BUT HER FATHER RESISTED EDUCATING A DAUGHTER.

Rosalind Elsie Franklin was born in London in 1920. She was one of five children born into a wealthy Jewish family. She decided she wanted to become a scientist at 15, and passed the admissions exam for Cambridge University. However, her father, Ellis, a merchant banker, objected to women going to college and refused to pay her tuition. Her aunt and mother finally managed to change his mind, and she enrolled at Cambridge's all-female Newnham College in 1938.

2. SHE ATTENDED COLLEGE WITH ANOTHER WOMAN WHO DIDN'T GET FULL CREDIT FOR HER WORK.

Bletchley Park cryptanalyst Joan Clarke was a few years older than Franklin, but they were both at Newnham in the late 1930s. Clarke would go on to be recruited for the war effort, cracking the German Enigma codes. The full scope of Clarke's work is still unknown, due to government secrecy.

3. HER SCHOLASTIC ACHIEVEMENTS WERE DENIED BY HER UNIVERSITY FOR YEARS.

Newnham College, Cambridge
Azeira, Wikimedia Commons // Public Domain

Despite Newnham College having been at Cambridge since 1871, the university refused to accept women as full members until 1948, seven years after Franklin earned the title of a degree in chemistry. Oxford University started granting women's degrees in 1920.

4. HER RESEARCH ON COAL HELPED THE AEROSPACE INDUSTRY.

After graduation, Franklin got a job at the British Coal Utilization Research Association (BCURA), where she researched coal and charcoal, and how it could be used for more than fuel. Her research formed the basis for her 1945 doctoral dissertation; it and several of her later papers on the micro-structures of carbon fibers played a role in the eventual use of carbon composites in air- and spacecraft construction.

5. HER MALE COLLEAGUES WERE HOSTILE AND UNDERMINED HER RESEARCH.

Franklin had a direct nature and was unwilling to be traditionally feminine. One reason she left Cambridge to work on coal was that her doctoral supervisor did not like her and believed women would always be less than men. When she was hired in 1951 at King's College, London, to work on DNA, she clashed with researcher Maurice Wilkins, who had thought she was his assistant, not his equal. Meanwhile, Franklin was under the impression that she'd be completely independent. Their relationship got worse and worse the longer they worked together. Wilkins went so far as to share Franklin's research without telling her with James Watson and Francis Crick—even though they were technically his competitors, funded by Cambridge University. Watson was particularly nasty about Franklin in his 1968 book, The Double Helix, criticizing her appearance and saying she had to be “put in her place.”

6. HOW EVENTS UNFOLDED IN THE DISCOVERY OF DNA'S STRUCTURE IS STILL DEBATED TODAY.

Double helix of DNA
Altayb, iStock

Many books have been written hashing over events, either criticizing Watson and Crick, saying they stole Franklin's research, or defending the duo, saying her research helped them but that Franklin would not ultimately have reached their conclusions on her own. Though Franklin and Watson never became friendly, Crick and his wife welcomed Franklin into their home while she was being treated for ovarian cancer.

7. HER WORK MAY HAVE LED TO HER UNTIMELY DEATH.

Franklin died of cancer in 1958. She was 37. Though genetics likely played a part in her illness, her work with crystal x-ray diffraction, which involved constant exposure to radiation, did not help. She is not the first woman in science to risk her health for her research. Marie Curie died from aplastic anemia, which has been tied to radiation exposure. Many of Curie's personal belongings, including her cookbooks, are too radioactive to handle even today.

8. HAD SHE LIVED LONGER, SHE MAY HAVE QUALIFIED FOR MORE THAN ONE NOBEL PRIZE.


Maurice Wilkins (on left), Francis Crick (third from left), and James Watson (fifth from left) accept their Nobel Prize in 1962.
Keystone, Getty Images

The first, of course, would have been awarded with Watson, Crick, and Wilkins, had they been made to share credit with her. (Pierre Curie had to ask the Nobel Committee to add his wife to the nomination in 1903.) As for the second, chemist Aaron Klug won the prize in 1982, carrying on work he and Franklin had started on viruses in 1953, after she left King's College. Because of the rules at the time of her death about awarding prizes posthumously (and in 1974 all posthumous awards were eliminated, the sole exception being in 2011), Franklin has none.

9. DESPITE BEING DENIED HER PRIZE, SHE'S BEEN HONORED BY MANY ACADEMICS.

In 2004, the Chicago Medical School renamed itself the Rosalind Franklin University of Medicine and Science. She has also had a number of academic programs, auditoriums, and labs named for her. In 2013, Newnham College principal Dame Carol Black helped install a plaque commemorating Franklin at the Eagle Pub in Cambridge. Crick and Watson, who already had a plaque in the pub, drank there often while working on the DNA project, and allegedly boasted about discovering “the secret of life” to other patrons.

10. SHE IS THE SUBJECT OF SEVERAL BIOGRAPHIES.

The first, 1975's Rosalind Franklin and DNA, was written by her friend Anne Sayre, largely as a reaction to Watson's The Double Helix. In 2002, Brenda Maddox published Rosalind Franklin: The Dark Lady of DNA.

11. AN OBJECT IN SPACE IS NAMED AFTER HER.

In 1997, amateur Australian astronomer John Broughton discovered an asteroid, which he named 9241 Rosfranklin.

12. AT LEAST ONE HISTORY RAP BATTLE IS ABOUT HER.

It was produced by seventh graders in Oakland, California (with some help from teacher Tom McFadden). And it is delightful.

13. SHE HAS BEEN IMMORTALIZED ON THE SMALL SCREEN AND THE BIG STAGE.

In 1987, BBC's Horizon series aired The Race for the Double Helix, starring Juliet Stevenson as Franklin. Jeff Goldblum played Watson. In 2011, playwright Anna Ziegler premiered a one-act about Franklin called Photograph 51. It opened on the West End in 2015, starring Nicole Kidman as Franklin.

14. THE 2015 RUN OF PHOTOGRAPH 51 RE-IGNITED THE OLD CONTROVERSY.

While Kidman got much praise from critics for her turn as Franklin in Photograph 51, Maurice Wilkins' friends and former colleagues have taken exception to a scene where Wilkins takes a photograph—the titular Photo 51, which showed evidence of DNA's structure—from Franklin's desk when she isn't there, saying he would never have done something so dishonorable.

15. THE PLAY MAY COME TO THE BIG SCREEN IN THE NEXT FEW YEARS.

In 2016, the West End production's director, Michael Grandage, told The Hollywood Reporter that he hopes to turn the play into a film, with Kidman reprising the role.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios