The Gastric Storage Tank

Written by Science Knowledge on 1:43 AM

Your stomach is a temporary storage tank. Empty, it holds less than a child’s juice box does. Swollen with food, it expands a staggering 30 to 50 times— large enough to accommodate nearly a gallon of food and drink.

Your stomach is also a muscle—one that few of us have trouble exercising. It expands and contracts continually, kneading, twisting, compressing, and mixing your food with powerful gastric juices that help digest it. The more food you put in your stomach, the more vigorous the mixing. When your stomach is empty, you might hear the noisy rumbles that biologists call borborygmus (pronounced “bore-bo-rig-mus”), but you call growling.

As your stomach churns your food, the meal gradually takes on the consistency of a creamy paste. Roughly three times a minute, your stomach squirts out a small eyedropper’s worth of this paste into your small intestine (which is the next stage in the digestive journey). In this way, your stomach slowly works through your breakfast, preparing it for further digestion, being careful not to hurry the job and overwhelm your intestines.

Your stomach passes along almost all the food it receives. However, some substances can dissolve through the thick coating of mucus that lines your stomach and enter your blood. Examples include alcohol and certain drugs, like aspirin.

It usually takes 2 to 4 hours for your stomach to empty itself. Fluids and carbohydrates pass through it quite quickly, while protein takes longer, and fat forms an oily layer that’s digested still more slowly. Large, fatty meals can linger for 6 hours or more. In the sample breakfast meal used here, the last holdout is the sausage, which supplies half of its calories from fat. For that reason, the sausage is also the most likely part of your meal to return as heartburn

Ideally, you’ll eat food that won’t race through your system or overstay its welcome. If you eat meals that have a dash of unsaturated fat and a good dose of fiber, you’ll process them steadily but gradually, and you’ll feel full longer. You’ll also avoid the sudden sugar rush and insulin release that raw carbohydrates cause—a process that can, over the years, encourage diabetes.

Source of Information : Oreilly - Your Body Missing Manual

Saliva

Written by Science Knowledge on 1:42 AM

Saliva is a watery, frothy substance that your mouth manufactures continuously. It trickles out through glands scattered around your mouth, cheeks, and throat, but most of it seeps up from under your tongue. You produce a small milk-carton’s worth (1 liter) of the stuff every day, most obviously when you eat, and hardly at all when you sleep.

Saliva cleans your teeth, lubricates your mouth, and protects the tender tissues inside. It also dissolves the substances in your food so they can reach your taste buds. In fact, without saliva, your favorite meal would be as appetizing as a stick of chalk.

Saliva also contains enzymes that start breaking down the long chains of complex carbohydrates in your food. (Enzymes are special compounds your body builds and then uses to carry out complex chemical reactions, like digestion.) For example, in the breakfast meal you’re chewing right now, enzymes split some of the starches in your toast. It’s all a bit of a preview to the heavy-duty digestion that takes place lower down the digestive tract. Saliva also moistens your food so your teeth can compact it into a small, soggy ball that’s ready to shoot down your throat and into your stomach.

Once your teeth and salivary glands have done their work, it’s time to swallow hard and move on. Your meal has now entered the winding passages of your digestive tract, where it will remain for the rest of its journey.

Although saliva includes its own natural antibacterial agents, opinions differ about whether the distinctly icky practice of licking wounds is healthy or dangerous. One thing is certain: Putting your tongue to a cut introduces not just antibacterial substances, but a huge family of mouth-dwelling bacteria, too—some of which can cause real trouble if they make their way deeper into your body.

Source of Information : Oreilly - Your Body Missing Manual

Bad Breath

Written by Science Knowledge on 1:40 AM

Basic dental hygiene removes particles of trapped food that can create an unpleasant mouth odor as the food decays. But a variety of other things can contribute to bad breath, such as:

• Dry mouth. Without the cleansing power of saliva, dead cells build up and decay in your mouth. This is the source of the phenomenon called morning breath, and it’s particularly bad if you sleep with your mouth dangling open.

• Digested food. Certain foods, like garlic, have volatile oils that can stink up your airways. There’s no way to rid yourself of these odors, because the odor begins after you absorb and process the food—and it actually seeps out of your lungs. Fortunately, the scent should die down in 24 hours. In the meantime, you can try to mask it by chewing on a clove, some mint, or a sprig of parsely (and hope that this combination doesn’t create a still more objectionable smell).

• Dental problems. When bacteria works itself into places it shouldn’t be—such as the pockets between your teeth and gums—it’s impossible to remove on your own. The problem usually begins with poor dental hygiene, and you can only fix it with a trip to the dentist.

• Diseases. Certain medical conditions can produce strange or offensive smells. For example, untreated diabetes can cause a fruity smell. Kidney failure can cause an ammonia-like smell. If you suddenly develop a new and unpleasant mouth odor, check it out with your doctor.

Source of Information : Oreilly - Your Body Missing Manual

Mouth Maintenance

Written by Science Knowledge on 2:38 AM

Different animals have very different ways of producing and maintaining their teeth. Sharks grow a limitless supply and never need to see a dentist. Elephants get a lifetime allotment of just 24 teeth and use no more than six at a time. As an elephant grinds its way through its tough, plant-based diet, its front teeth wear down and eventually fall out, making room for its back teeth to move forward as replacements. When an old elephant goes through all of its teeth, it starves to death.

Humans aren’t quite as bad off—if we lose our limited set of 32 teeth, we can survive on protein shakes and peach ice cream. But if you want to bite your way through chocolate bars and ciabatta bread well into your nineties, you need to make sure your dental hardware doesn’t end up as used and abused as a mouthful of elephant teeth.

Here’s what you need to know to maintain healthy teeth:

• Brushing. It’s not necessary (or helpful) to attack your teeth with sandblasting force. Instead, a gentle 3- to 4-minute brushing does the trick. (Most people think they brush even longer, but the average brushing session lasts just 60 seconds.) Twice a day is the official tooth-brushing recommendation, but dentists really want you to clean your teeth after every meal. Modern research suggests you wait 20 minutes after a meal before you brush. Immediate brushing attacks your teeth when they’re at their softest—weakened by the acids in your food.

• Flossing. Studies suggest that proper flossing might do more for your teeth than brushing. Flossing once a day won’t bankrupt your dentist, but it will remove tiny particles of food between your teeth and reduce the sticky buildup of plaque. To get the most out of flossing, however, you need impeccable technique. Particularly important is flossing gently under your gumline, as shown in the picture below. For a step-bystep walkthrough, point your Web browser to http://tinyurl.com/cltjjy. Too pressed for time to clean your teeth with a strip of floss? As sardonic dentists often remark, you need to floss only the teeth you want to keep.

• Whitening. Stained, discolored teeth get little love. But recently, tooth fashion has switched from cloud white to glistening-Chiclets white, and the effect can be as glaringly unnatural as a nose job on Cyrano de Bergerac. If you really want a brighter shade of white, skip whitening toothpastes—most of them simply include abrasives that can grind away some surface marks. However, home whitening kits and custom dental appliances can produce better results, so talk to your dentist about what sort of whitening product would be most effective for you. This is particularly important if you’ve had any serious dental work.

• Gum disease. The real danger of poor dental hygiene isn’t cavities (which are usually easy to patch), but gum disease. Gum disease occurs when the same bacteria that attack your teeth slip under your gumline, damaging your gums (in which case it’s called gingivitis) or into your teeth’s supporting tissues and bone (in which case it’s called periodontitis). The former can make your gums swell and bleed, and can trigger bad breath. The latter can destabilize your teeth and lead to a set of dentures.

• Fluoride. Conspiracy theorists aside, fluoride plays an important role in strengthening tooth enamel, especially early in life. Countless studies have nearly always agreed about fluoride’s cavity-preventive abilities and its lack of side effects, which is why it’s so often included in municipal water supplies or (in many non–English-speaking countries) added to table salt. The only catch is that too much fluoride can stain the teeth of young children, but that won’t happen unless they abuse fluoridated mouthwashes or eat entire tubes of toothpaste. (Incidentally, in the 1950s, far-right activists opposed fluoridation and vaccination, believing both were part of a shadowy conspiracy to impose a communist regime on America. So consider yourself forewarned.)

There’s a more controversial ingredient in some toothpastes: triclosan, an antibiotic that coats the teeth. Studies confirm that it’s an effective tool against the bacterial marauders that live in your mouth and cause plaque. However, some health experts worry that it could lead to bacterial resistance —in other words, the presence of triclosan could encourage harmful bacteria to evolve into a super-species that’s immune to the usual antibiotic weaponry. If you’re looking to give your teeth an antibiotic boost—or if you just want to avoid this high-powered ingredient—check the label. Colgate Total is the best-known toothpaste to include triclosan.

Source of Information : Oreilly - Your Body Missing Manual


About Me

In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.


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