10 Vital Facts About the Scrotum

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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. Our series The Body explores human anatomy, part by part. Think of it as a mini digital encyclopedia with a dose of wow.

The scrotum may appear to be nothing more than a bit of baggy skin, but it serves some very important functions for human health and reproduction. The testicles, which produce sperm, would be unprotected and subject to the elements without the scrotum—so without it, none of us might exist. To learn more, Mental Floss spoke to Brian Levine, a reproductive endocrinologist and fertility specialist at the New York office of the Colorado Center for Reproductive Medicine. 

1. THE SCROTUM HAS BUT ONE HUMBLE PURPOSE.

"The scrotum is a genius," Levine tells Mental Floss. While that may be a stretch, he says that the main purpose of the scrotum "is to hold the testicles outside of the body," which helps to keep the testicles cooler than body temperature. Because sperm are so sensitive to temperature fluctuations, this helps preserve their health.

2. HOT TESTICLES CAN CAUSE HEALTH AND FERTILITY PROBLEMS.

"Increased body temperature or temperature in general [such as a hot tub] leads to chromosomal abnormalities. By keeping the temperature lower you protect the DNA being formed to put the sperm together from having inborn errors," Levine explains.

3. TEMPERATURE REGULATES TESTICLE HEIGHT.

As the body gets colder, muscle fibers bring the scrotum closer to the body to regulate them. When the person is warmer, they will hang lower from the body. "The average person has one testicle higher than the other," Levine says. Size and shape variance of testicles is not in and of itself cause for concern—unless you experience a sudden change.

4. COOLER SPERM ALSO SWIM BETTER …

Also by keeping the testicles at a lower temperature, metabolically, Levine says, "you keep sperm swimming slower, so you end up preserving them."

5. … WHICH IS WHY SOME HAVE SUGGESTED EXPOSING THE SCROTUM TO OPEN FLAME OR A HOT-WATER SOAK.

A 2013 study [PDF] on birth control methods of an indigenous culture in Zimbabwe describes how men were instructed to expose their testicles to "above average heat from fire" in the belief that this would weaken the sperm. While there is a connection between temperature and sperm health, this is not a recommended practice for birth control as it is unlikely to successfully reduce the sperm count. In addition, the study notes, "testicles with too high of a body temperature are associated with testicular cancers," though others argue that the jury is still out on that purported connection. Either way, you should probably keep your scrotum away from open flame.

In a similar vein, Marthe Voegeli, a Swiss doctor and early pioneer in fertility in the 1950s, designed a study in which men sat in a shallow or testes-only bath of 116°F for 45 minutes daily for three weeks. Her study claimed that this resulted in between four and six months of infertility. Fertility returned to normal eventually, and children born of those men were healthy and normal. She took her method to India, to help families suffering from famine and poverty prevent further pregnancies. While she claimed her methods to be successful, most doctors today would not recommend this as a reliable contraceptive practice.

6. YOU CAN GET MELANOMA OF THE SCROTUM.

Even the scrotum is susceptible to cancer, Levine points out. "Wherever there's skin, you can get melanoma," he says. This can be a result of metastases of cancer that spread from somewhere else in the body, or, if you're a nude sunbather, be warned: "If you expose it to sunlight, you can get melanoma."

7. LACK OF A SCROTUM CAN MEAN THIS …

If you are male, not prepubescent, and don't have a scrotum, it may mean you have undescended testicles, Levine says, "which can end up leading to infertility." Most testicles will descend eventually, but sometimes they can be helped along by surgery.

8. BE AWARE OF THESE COMMON CONDITIONS OF THE SCROTUM.

Common issues of the scrotum that may require surgical intervention include varicoceles, which are essentially varicose veins in the scrotum that can cause infertility by pooling blood, which can effect sperm count and motility. Varicoceles can also cause testicles to fail to develop normally or shrink. A hydrocele, which doctors informally call "water on the testicle," Levine says, is simply a fluid-filled cyst that surrounds a testicle and causes swelling in the scrotum. Levine adds that since the scrotum allows for good evaluation of testicles, "If you feel any lumps, bumps or abnormalities, you should see a medical professional."

9. SURGICAL TECHNIQUES FOR THE SCROTUM AND TESTICLES HAVE COME A LONG WAY.

Should you need surgery for one of those conditions, or for a vasectomy, Levine reassures that modern day surgical techniques "mostly spare the scrotum and require a minimal, barely visible incision in the testicle." Weill Cornell Medical Center has even perfected what they call a no-scalpel vasectomy that uses specialized forceps instead.

10. WHY WERE CHIMNEY SWEEPS PRONE TO SCROTAL CANCER?

In the late 1700s and early 1800s, chimney sweeps—who were often young boys because they were small enough to fit—would develop scrotal cancer from creosote collecting between the skin folds on the scrotum.

Sir Percival Pott, an English surgeon considered the father of orthopedics and the first to draw the connection between occupations and certain illnesses, also made the connection between chimney sweeps and scrotal cancer, writing: " … there is a different disease peculiar to a certain set of people, which has not, at least to my knowledge, been publicly noticed; I mean the chimney-sweeper's cancer. It is a disease which makes its first attack on, and appearance in, the inferior part of the scrotum; where it produces a superficial, painful, ragged, ill-looking sore, with hard and rising edges: the trade call it the soot-wart." (We know now that a chemical in soot caused genetic damage to chromosome 17.)

After this connection was made, physicians recommended that chimney sweeps change their clothes weekly and wash their genitals daily.   

10 Smart Facts About Your Gut

Colorized scanning electron micrograph of E. coli, a common gut bacteria
Colorized scanning electron micrograph of E. coli, a common gut bacteria
National Institute of Allergy and Infectious Diseases, Flickr // CC BY 2.0

Gut feelings get all the press, but your gut may be more of a thinker than you know. Some scientists now consider it a second brain. While it won’t necessarily help you study for an exam or get a promotion, your gut can influence the chemistry of your mood, emotions, immune system, and long-term health. Research even suggests the gut can “learn” new tricks through conditioning. These powerful connections are part an emerging field of science called neurogastroenterology designed to study the gut-brain link. Here are 10 facts you may not know about your gut.

1. THE GUT DOESN'T NEED THE BRAIN'S INPUT. 

You might think of your gut as a rebel against authority. It doesn’t wait for your brain’s impulses to do the important work of digestion, because it doesn’t need to—it acts as its own “brain.” No other organ, not even the all-powerful heart, can pull that off.

2. THERE ARE MORE THAN 100 MILLION BRAIN CELLS IN YOUR GUT.

Your gut’s power to think for itself is no surprise; there are millions of neurons in its lengthy coils (9 meters of intestines, from esophagus to anus). That’s more neurons than are found in the spinal cord or peripheral nervous system.

3. YOUR GUT HAS ITS OWN NERVOUS SYSTEM.

The enteric nervous system—the controlling mechanism of digestion and elimination—is the overlord of your gut, and functions all on its own. Some scientists see it as part of the central nervous system, while others consider it its own entity. It likely evolved to give the gut the go-ahead when the “got to go” impulse strikes, without requiring the brain’s sign-off, particularly when you consider the helplessness of an infant with its brand-new brain.

4. THERE'S AN INFORMATION HIGHWAY FROM YOUR GUT TO YOUR BRAIN.

There’s one big visceral nerve embedded in your gut—the vagus nerve. Research has revealed that up to 90 percent of its fibers carry information from the gut to the brain, rather than the other way around. In other words, the brain interprets gut signals as emotions. So you really should trust your gut.

5. MOST OF YOUR SEROTONIN IS IN YOUR GUT.

Some 95 percent of your body’s serotonin, that marvelous mood molecule that antidepressant drugs like Prozac keep in your body, can be found in the gut. So, it’s no wonder that diet, medications, and antibiotics can wreak havoc on one’s mood.

6. A HEALTHY GUT MAY PROTECT YOUR BONES.

In a study of the serotonin-gut relationship, scientists discovered an unexpected link between the gut and the bones. Inhibiting the gut’s release of serotonin counteracted the bone-density reduction of osteoporosis in mice. This research is going into studies on new osteoporosis-fighting drugs.

7. RESEARCH SHOWS LINKS BETWEEN AUTISM AND HAVING FEWER STRAINS OF GUT BACTERIA. 

In as many as nine out of 10 cases, autistic people have common gut imbalances such as leaky gut syndrome, irritable bowel syndrome, and fewer strains of “good” bacteria. Research on mice is looking at possible treatments of some of the behavioral disorders of autism by balancing microbes in the guts, though many warn that such treatments can’t produce a “cure” for autism.

8. FOOD REALLY DOES AFFECT YOUR MOOD. 

Different foods, when introduced to the gut via feeding tubes, have been shown to change a person's moods without the person’s awareness of what they were "eating." Fat, for instance, increased feelings of happiness and pleasure (no surprise there) because appeared to trigger the release of dopamine—the brain’s natural opiate. Carbohydrate consumption stimulated the release of serotonin, the “feel good” neurotransmitter.

9. YOUR GUT IS YOUR BEST FRIEND IN COLD AND FLU SEASON.

Not only does your gut hold brain cells, it also houses the bulk of your immune cells—70 percent—in the form of gut associated lymphoid tissue, or GALT, which plays a huge part in killing and expelling pathogens. GALT and your gut microbiome—the trillions of bacteria that live, like an immense microbial universe, in your gut—work hard to help you get over what ails you. That’s all the more reason to be careful with the use of antibiotics, which wipe out the good bacteria along with the bad.

10. YOUR GUT CAN BECOME ADDICTED TO OPIATES.

Inside your gut are opiate receptors, which are also found in the brain. The gut is just as susceptible to addiction as the brain and may contribute to the intense difficulty some addicts have trying to kick the habit.

What Causes Hiccups?

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iStock/damircudic

The cause of hiccups depends on whom you ask. The ancient Greek physician Galen thought hiccups were violent emotions erupting from the body, while others thought they were a sign of liver inflammation. Today, evidence points to spasms in the diaphragm, the large muscle between the chest and abdomen that aids airflow during breathing. This involuntary contraction can be brought on by a number of things that might irritate the nerves that control the movement of the muscle. A full stomach, heavy boozing, rapid shifts in temperature either inside or outside of the stomach, and certain emotions like shock or excitement are all common culprits.

No matter the cause, the result is the same: The diaphragm spasms and causes us to take a quick breath. The sudden rush of air causes the epiglottis (the flap that protects the space between the vocal cords) to shut and interrupt the breath, which makes the familiar "hic" sound.

WHAT CURES THEM?

The best cure for hiccups also depends on the person you ask. Almost all cures are based on one of two principles: One type works its magic by overwhelming the vagus nerve with another sensation. The vagus nerve is a cranial nerve that innervates the stomach and conveys sensory information about the body's organs to the brain. When distracted by overwhelming information of another sort, it basically tells the brain that something more important has come up and the hiccuping should probably be stopped (vagus nerve stimulation is also used to control seizures in epileptics and treat drug-resistant cases of clinical depression). The other method for curing hiccups is to interfere with the breathing, increasing the amount of carbon dioxide in the blood, and causing the body to focus on getting rid of the of the CO2 and not making hiccups.

Swallowing a spoonful of sugar is probably the most commonly prescribed hiccup cure and falls into the first category. A teaspoon of sugar is usually enough to stimulate the vagus nerve and make the body forget all about the hiccups. Even ardent supporters of the sugar cure disagree if the sugar should be taken dry or washed down with water, though.

If this home remedy doesn't work, and your hiccups are both severe and persistent, you may need to bring out the big guns. For chronic cases like this, doctors sometimes use a cocktail of Reglan (a gastrointestinal stimulant) and Thorazine (an anti-psychotic with sedative properties) to quiet things down. In some cases that resist these drugs, Kemstro, an anti-spasmodic, is also used. Other doctors have used vagus nerve stimulators implanted in the upper chest of patients. The pacemaker-like devices send rhythmic bursts of electricity through the vagus nerve to the brain to keep the hiccup cycle in check.

Many people prefer home remedies to battle their hiccups, which may include holding your breath, gargling ice water, or breathing into a paper bag. While the same people will swear by the treatment they've been using all these years, there's no firm scientific consensus that any of them actually work. But if it helps you, isn't that all that matters?

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

An earlier version of this article appeared in 2012.

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