Your tongue can pick up 5 different types of taste sensations

Back in grade school, you probably learned that the human tongue can pick up four different kinds of tastes: sweet, sour, salty and bitter. But those textbooks left out another flavor sensation: umami. Taken from the Japanese word for "yummy," umami was first identified as a primary flavor back in 1908 by a Japanese chemist who was inspired to look for it after eating a bowl of seaweed soup. He found a chemical that is to umami what sugar is to sweet. It's monosodium glutamate, or MSG. But MSG isn't the only way to tickle your umami taste buds. Often described as the "savory" taste, umami sensations are naturally produced by foods like meat, aged cheese, tomatoes and mushrooms.

You have 2 million tiny hairs in your inner ear

Unlike hair growing on the surface of your ears, the presence of hairs, or "stereocilia," deep inside your head aren't considered a hygiene lapse. Instead, they're a vitally important part of your ability to hear, responsible for changing physical sound waves into electrical signals that can be understood by your brain, according to the British Hearing Research Trust. When stereocilia are hit with a sound vibration, they produce electricity and begin to "dance," stretching and compressing. In May 2008, researchers at St. Jude's Children's Research Hospital in Memphis figured out that this dancing, and the protein that causes it, is probably how stereocilia amplify sounds. If those tiny hairs can't dance, the brain they're connected to can't hear high-frequency sounds and might even be rendered deaf.

The average person's body holds 1.3 gallons of blood

There's more than a milk jug full of fluid coursing through your veins, where it functions somewhat like a courier service. Blood is responsible for both delivering the things your body desperately needs—like oxygen—and carting off the things it desperately needs to throw out, like the toxic wastes that end up being filtered out of the body by the kidneys. And it does all of this very, very fast. The heart, the organ responsible for getting all that blood to move around, pumps as much blood as is in the body every minute; when you're sitting still, that is. Up your activity level and your heart can end up pumping more than five gallons of blood per minute.

You use 100% of Your Brain

Think you're only using 10 percent of your possible brain power? Think again. A little critical thinking will have you calling shenanigans on that myth. After all, if you removed 90 percent of your brain, you'd basically be left with the thinking power of a sheep, according to Eric Chudler, Ph.D., research associate professor in the department of bioengineering at the University of Washington. Dr. Chudler has attempted to trace the history of the "10 percent myth" and written several articles on the topic. He reports that, during a functional magnetic resonance imaging (fMRI) scan, doctors can see what areas of the brain are being used, based on how much blood is being directed there. According to Dr. Chudler, 100 percent of the brain has been shown to have a function.

The eye has three separate processing systems

New research shows it takes a village to help you see, according to the Society for Neuroscience. Right now, we know of at least three separate processing systems that help your brain make sense of visual data: One that focuses on shape, another devoted to color, and a third that takes on the task of interpreting movement and location. The Society reports that psychologists have found that humans can see and understand things like depth perception and texture even without color being involved. Instead, contrasts in light intensity help us pick up on this information.

Did You Know?

Some aquatic insects and spiders carry an air supply when they dive? These creatures (such as backswimmers, water boatmen, and water spiders) have tiny, water-repelling hairs that hold air bubbles next to their bodies. Oxygen diffuses into these external "lungs" and carbon dioxide diffuses out, enabling the bugs to breathe without surfacing.