My Science School

Everybody yaws – even unborn babies in the womb – and yet researchers aren’t quite sure why we do it. Although humans yawn more often when we’re tired or bored, scientists have ruled out sleepiness or lack of oxygen (which would cause sleepiness) as causes. Instead, they suspect yawning might help us keep a cool head. As with a super computer, the brain needs to stay cool to function properly. Each yawn pumps air into sinus cavities in the head, cooling the brain in the process. And because the brain and body are slightly warmer just before bed, we tend to yawn when we’re tired.

 

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When it comes to retaining memories, your brain is practically a bottomless pit – one that continues to deepen throughout your life. So why did you forget where you put your towel at swim practice? It turns out your brain is equipped with two types of memory...

Short-term: Powerful but fleeting, short – term memory is meant to store information – such as phone numbers, email addresses, and other humdrum everyday data, like the location of that towel at swim practice – that you won’t need to recall during your golden years. As you’d expect, short-term memories don’t linger. They fade even faster if you were distracted at the time the memory took shape (maybe a teammate was talking to you while put down your towel, or maybe you moved the towel many times during practice and your short – term memory can’t place its exact location).

Long-term: Experiences move from short-term to long-term memory when they’re  repeated (such as when you memorize flash cards to study for a test) or accompanied by meaningful emotions and significant sensory input (such as when you scored the winning goal or the day you got your pooch as a puppy). Scientists believe your brain has a limitless capacity for long – term memories, but sometimes you can’t recall a particular detail without help from sensory clues (a familiar smell is a powerful reminder) or the recollections of friends involved in the event.

Scientists blame such forgetfulness on a flaw on our ability to retrieve memories – a flaw that nonscientists call a ‘’brain fart’’.

 

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Every time you experience something new, electrical charges fire through the white matter in tour brain, creating chemical links that form a network of pathways out of neurons. Your memories are stored in these connected neurons, and the connections become stronger and expand into other neurons with repeated exposure to the new experience. Practicing a song on the guitar makes the same neural networks fire again and again, becoming stronger and thus making the song easier to play. Spending time with a new friend reinforces old connections and builds new ones as you learn about your pal’s habits. As you learn and gain new memories, your brain’s structure changes and makes new connections. The brain you have today will be different tomorrow.

 

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Your cerebellum, the second largest part of your brain, coordinates the movement of your muscles and keeps you from tumbling over when you walk. The frontal lobes process your thoughts and speech, as well as learning, emotions, and some types of memory. Your senses of pain, touch, heat, and cold are handled by the parietal lobes behind the frontal lobes. The occipital lobes at the back of the brain decode visual information from our peepers. The temporal lobes, near your temples, process memories and sounds transmitted from your ears. The entire cerebrum is enveloped in a layer of gray matter called the cerebral cortex. Its deeply wrinkled surface packs maximum processing power into the tight quarters of your skull.

 

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Credit of your uniquely human intellect – your ability to solve algebra problems or play the electric guitar or wonder about the function of your own brain – goes to your cerebrum. Accounting for 85 percent of your brain’s mass, it’s far larger and more complex than the cerebrums of other brainy animals such as dolphin, whales and elephants. It’s also home to your brain’s most important lobes – the sub – processors of that supercomputer between your ears.

 

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It’s a reassuring idea for anyone who thinks they have superpowers or hidden artistic talents: We could accomplish amazing facts if we could just tap into our unused reserves of gray matter. It’s also a total myth. We use nearly every part of our brain all the time. Even a simple activity like brushing your teeth – walking toward the toothbrush, squeezing out just enough toothpaste, keeping track of which teeth you’ve cleaned as you brush away – activates a small electrical storm across your brain as the various lobes, cortices, and cerebellum work together to brush, rinse, spit, and remember to floss. The activity in your brain never stops, even when you sleep.

 

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Your brain is a delicate organ that needs all the protection it can get. That thick skull of yours is its first line of defence (being boneheaded is a good thing!), followed by three sturdy membranes called meningitis. Fluid files the gaps between these membranes, cushioning the brain from impacts. A special ‘’blood – brain barrier ‘’made of special cells acts like a security perimeter in the brain’s circulatory system, and keeps out anything that might contaminate your sensitive network of neurons.

 

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The electrical messages bouncing across your brain at any given time outnumber the messages zipping through the world’s telecommunications networks. All that activity requires enough electricity to power a dim light bulb. That might not sound like much until you consider the brain uses 20 percent of the body’s energy but is only about 2 percent of its weight.

The brain consumes a huge amount of energy compared to other organs, 20–25% of total consumption, whether we are resting or physically active, and despite being only 2% of our total weight. Most vertebrates devote 2–8% of total energy to their brain, but in primates the percentage is much higher, with humans using the most. From this we can probably conclude that high energy use is a requirement for intelligence.

 

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You have two lungs and two kidneys, but you have only one brain. Make the most of it – and complement its own built-in safety features – by following these tips:

Wear a helmet: While riding your bike, skateboarding, snowboarding, or an engaging in any other potentially dangerous activity.

Don’t smoke: Not only is it bad for your lungs, but it can cause neurological damage to your brain as well.

Eat well: A poor diet can lead to illnesses later in life (such as type 2 diabetes and high blood pressure) that can cause shrinkage of the brain.

Exercise your body: Running, playing, soccer, and other physical activity releases chemicals that refresh your brain and prime it for learning.

Exercise your mind: Games that test your memory and concentration actually improve your brain’s flexibility in processing information and can possibly help you dodge dementia (a disease that affects your mental abilities) later in life.

 

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Gray matter has some pink and yellowish tints mixed in. White matter is really more pinkish. It turns white when it dies and has been preserved as a lab specimen.

Gray matter is mostly neuron cell bodies and non-neuron brain cells called glial cells. These glial cells provide nutrients and energy to neurons. They help transport glucose into the brain, clean the brain of excess chemicals and may even affect the intensity of the neurons' communications.

The white matter of the brain is made up primarily of axon tracts, the long, spindly appendages of some brain cells. These tracts transmit the electrical signals that the brain cells, called neurons, use to communicate. They're wrapped in a fatty layer called myelin, which insulates the axons and allows them to conduct signals quickly, much like rubber insulation does for electrical wires. The type of fat in myelin makes it look white, so myelin-dense white matter takes on a white hue as well.

 

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One of your body’s largest organs, your brain is three pounds (1.3kg) of fat and proteins condensed in a mass with a tofu-like texture. Its contents come in two colors...

Gray matter: Your brain contains about 100 billion nerve cells. Called neurons, they make up your brain’s ‘’gray matter’’

White matter: Your neurons communicate with one another by sending electrical signals and forming chemical connections in a network of nerve fibers called dendrites and axons, which form your brain’s white matter. This communication between neurons is what’s responsible for your every thought, memory, movement, and automatic bodily function.

 

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Like your wisdom teeth and your tailbone, goose bumps serve no purpose in modern humans. They’re created by itty-bitty muscles in our hair follicles, which raise the bumps as a reflex reaction to a sudden drop in temperature or feelings of panic, anger or extreme fear. Goose bumps fluffed up the body hair of our much furrier ancestors to help trap heat or make them look larger to threatening animals. Today, goose bumps just make you look like you need to borrow a sweater.

People also tend to experience goose bumps during emotional situations, such as walking down the aisle during their wedding, standing on a podium and listening to a national anthem after winning in sports, or even just watching horror movies on television. Quite often a person may get goose bumps many years after a significant event, just by thinking about the emotions she once experienced, perhaps while listening to the romantic song to which she danced many years ago with the love of her life.

 

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Called ‘’vestigial’’ organs, these useless body parts are leftovers from our evolutionary ancestors, who actually needed them. Take your wisdom teeth, for example. Today they crowd our mouth and often needed to get yanked by the dentist, but our primate ancestors had larger jaws and needed the extra choppers in case some rotted away in the days before tartar-control toothpaste. Our tailbone – or coccyx – is a leftover from animals that needed tails for balance or grasping trees branches. The gallbladder is a pouch that holds bile (made by the liver) and slowly releases it into the digestive tract. It also makes painful stones and can cause problems from cancer (which spreads to necessary organs) and inflammation. Most people that have to have it removed don’t notice much of a difference.

Paranasal sinuses are what most of us traditionally think of as our sinuses. As the name might suggest, they’re the four that surround our nose, and generally feel cruddy during allergy season and get infected and stuff. Yeah, we don’t need those. It’s theorized that our ancestors had extra smell receptors there, which would’ve been helpful in a hunter/gatherer society. Not so much in a society that has progressed enough to invent axe body spray.

 

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Human has evolved to become less hairy in the past six million years or so, but we still have those clumps of fur above our eyes. Beyond their role in our facial expressions, eyebrows act like natural sweatbands, preventing rain and sweat from running directly into our eyes. Eyebrows then took on another function: communication. Facial expressions convey meaning and emotions in ways that are hard to fake, and the eyebrows exaggerate expressions. Even in cartoons, a simple line above the eyes is enough to denote anger, fear, or surprise in a face, and experiments have shown that we can recognize a familiar face more easily when the eyes are blanked out than when the eyebrows are.

 

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It’s a no-brainer that you need your brain and your heart, and you wouldn’t last long if you’re failed. But the lungs and kidneys come in pairs, so you could survive if one of them failed. People who’ve lost their spleens in accidents have gone on to live healthy lives. The tonsils and appendix, meanwhile, are practically useless and are routinely removed when they become inflamed.  People may have their colon removed as a way to treat colon cancer or Crohn's disease, or in some cases, to prevent colon cancer. People can live without a colon, but may need to wear a bag outside their body to collect stool.

 

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