Tuesday, April 14, 2009

10 Things You Didn't Know About You

The human body is a great, sweaty, fluid-filled machine, moving and mixing chemicals with precision and coordination, making everything from memories to mucus. Here we explore some of the complex, beautiful or just plain gross mysteries of how you function.
10 Things You Didn't Know About You // The digestive system (© Purestock/age fotostock)
Your stomach secretes corrosive acid
There's one dangerous liquid no airport security can confiscate from you: It's in your gut. Your stomach cells secrete hydrochloric acid, a corrosive compound used to treat metals in the industrial world. It can pickle steel, but mucous lining the stomach wall keeps this poisonous liquid safely in the digestive system, breaking down lunch.
10 Things You Didn't Know About You // Man on one knee proposing marriage to woman (© Image Source/age fotostock)
Body position affects your memory
Can't remember your anniversary, hubby? Try getting down on one knee. Memories are highly embodied in our senses. A scent or sound may evoke a distant episode from one's childhood. The connections can be obvious (a bicycle bell makes you remember your old paper route) or inscrutable. A scientific study helps decipher some of this embodiment. An article in the January 2007 issue of Cognition reports that episodes from your past are remembered faster and better while in a body position similar to the pose struck during the event.
10 Things You Didn't Know About You // X-ray of skeleton (© MedicalRF.com/Getty Images)
Bones break (down) to balance minerals
In addition to supporting the bag of organs and muscles that is our body, bones help regulate our calcium levels. Bones contain both phosphorus and calcium, the latter of which is needed by muscles and nerves. If the element is in short supply, certain hormones will cause bones to break down, upping calcium levels in the body until the appropriate extracellular concentration is reached.
10 Things You Didn't Know About You // Model of the human brain (© Image Source/age fotostock)
Much of a meal is food for thought
Though it makes up only 2 percent of our total body weight, the brain demands 20 percent of the body's oxygen and calories. To keep our noggin well-stocked with resources, three major cerebral arteries are constantly pumping in oxygen. A blockage or break in any of them starves brain cells of the energy they require to function, impairing the functions controlled by the affected region. This is a stroke.
10 Things You Didn't Know About You // Illustration of egg and sperm (© Steve Taylor/Digital Vision/age fotostock)
Thousands of eggs unused by ovaries
The average adolescent girl has 34,000 underdeveloped egg follicles, although only 350 or so mature during her life (at the rate of about one per month). When a woman reaches her late 40s or early 50s, the monthly menstrual cycle that controls her hormone levels and readies ova for insemination ceases. Her ovaries have been producing less and less estrogen, inciting physical and emotional changes across her body. Her underdeveloped egg follicles begin to fail to release ova as regularly as before; the unused egg follicles then deteriorate. With no potential pregnancy on the horizon, the brain can stop managing the release of ova.
10 Things You Didn't Know About You // Teen about to spray paint a brick wall (© Image Source/Getty Images)
Puberty reshapes brain structure, makes for missed curfews
We know that hormone-fueled changes in the body are necessary to encourage growth and ready the body for reproduction. But why is adolescence so emotionally unpleasant? Hormones like testosterone actually influence the development of neurons in the brain, and the changes made to brain structure have many behavioral consequences. Expect emotional awkwardness, apathy and poor decision-making skills as regions in the frontal cortex mature.
10 Things You Didn't Know About You // Cilia (© Science Photo Library RF/age fotostock)
Cell hairs move mucus
Most cells in our bodies sport hair-like organelles called cilia that help out with a variety of functions, from digestion to hearing. In the nose, cilia help to drain mucus from the nasal cavity down to the throat. Cold weather slows down the draining process, causing a mucus backup that can leave you with snotty sleeves. Swollen nasal membranes or condensation can also cause a stuffed schnozzle.
10 Things You Didn't Know About You // Wisdom teeth (© BSIP Medical/Photolibrary)
Big brains cause cramped mouths
Evolution isn't perfect. If it were, we might have wings instead of wisdom teeth. Sometimes useless features stick around in a species simply because they're not doing much harm. But wisdom teeth weren't always a cash crop for oral surgeons. Long ago, they served as a useful third set of meat-mashing molars. But as our brains grew, our jawbone structure changed, leaving us with expensively overcrowded mouths.
10 Things You Didn't Know About You // Man and young girl laughing (© Ron Levine/Getty Images)
The world laughs with you
Just as watching someone yawn can induce the behavior in yourself, recent evidence suggests that laughter is a social cue for mimicry. Hearing a laugh actually stimulates the brain region associated with facial movements. Mimicry plays an important role in social interaction. Cues like sneezing, laughing, crying and yawning may be ways of creating strong social bonds within a group.
10 Things You Didn't Know About You // Four hands with different skin colors (© Sarah Leen/National Geographic/Getty Images)
Your skin has four colors
All skin, without coloring, would appear creamy white. Blood vessels near the surface add a blush of red. A yellow pigment also tints the canvas. Lastly, sepia-toned melanin, created in response to ultraviolet rays, appears black in large amounts. These four hues mix in different proportions to create the skin colors of all the peoples of Earth.

 
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