My Science School

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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This fragile first-shaped sack in your body’s infection fighter, filtering bacteria, viruses and other nasty invaders from your blood. Your spleen's main function is to act as a filter for your blood. It recognizes and removes old, malformed, or damaged red blood cells. When blood flows into your spleen, your spleen performs "quality control"; your red blood cells must pass through a maze of narrow passages. Healthy blood cells simply pass through the spleen and continue to circulate throughout your bloodstream. Blood cells that can't pass the test will be broken down in your spleen by macrophages. Macrophages are large white blood cells that specialize in destroying these unhealthy red blood cells.

The blood vessels in human spleens are able to get wider or narrower, depending on your body's needs. When vessels are expanded, your spleen can actually hold up to a cup of reserve blood. If for any reason you need some extra blood – for example, if trauma causes you to lose blood – your spleen can respond by releasing that reserve blood back into your system.

Your spleen also plays an important part in your immune system, which helps your body fight infection. Just as it detects faulty red blood cells, your spleen can pick out any unwelcome micro-organisms (like bacteria or viruses) in your blood.

 

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This organ injects special protein substances called enzymes into your small intestine to break down carbohydrates for fats and energy, and proteins for body-building materials. The pancreas has an endocrine function because it releases juices directly into the bloodstream, and it has an exocrine function because it releases juices into ducts.

Enzymes, or digestive juices, are secreted by the pancreas into the small intestine. There, it continues breaking down food that has left the stomach.

The pancreas also produces the hormone insulin and secretes it into the bloodstream, where it regulates the body's glucose or sugar level. Problems with insulin control can lead to diabetes. Other possible health problems include pancreatitis and pancreatic cancer.

A healthy pancreas produces chemicals to digest the food we eat. The exocrine tissues secrete a clear, watery, alkaline juice that contains several enzymes. These break down food into small molecules that can be absorbed by the intestines. When blood sugar falls, pancreatic alpha cells release the hormone glucagon. Glucagon causes glycogen to be broken down into glucose in the liver. The glucose then enters the bloodstream, restoring blood sugar levels to normal.

 

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This bean-shaped organ is so essential to good health that your body comes with a second one for free! Each kidney is crammed with more than a million microscopic filters-called nephrons – that skim the waste chemical and other gunk from your blood. One of the main jobs of the kidneys is to filter the waste out of the blood. How does the waste get in your blood? Well, your blood delivers nutrients to your body. Chemical reactions in the cells of your body break down the nutrients. Some of the waste is the result of these chemical reactions. Some is just stuff your body doesn't need because it already has enough. The waste has to go somewhere; this is where the kidneys come in. First, blood is carried into the kidneys by the renal artery (anything in the body related to the kidneys is called "renal"). The average person has 1 to 1½ gallons of blood circulating through his or her body. The kidneys filter that blood about 40 times a day! More than 1 million tiny filters inside the kidneys remove the waste. These filters, called nephrons, are so small you can see them only with a high-powered microscope.

 

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This skinny tube in our digestive system is mostly useless today and can actually endanger your life if it becomes inflamed. Scientists suspect that the appendix, which replenishes essential bacteria in our guts, was an important organ back before germ-fighting medicines helped humans overcome constant bouts of diarrhea. Scientists disagree on what the appendix actually does. Some think it's a leftover organ from earlier humans but that it no longer serves any purpose.

Other scientists think it's responsible for returning good bacteria to the gut after an infection. If the appendix really does serve as a source of good bacteria, then it is an important part of the human immune system. When your appendix becomes inflamed, it’s called appendicitis. It’s usually caused by a bacterial infection. The infection might start in your stomach and travel to your appendix. It might also arise from a hardened piece of feces in your intestinal tract. If you suspect you have appendicitis, make an appointment with your doctor. To diagnose your condition, they will ask you about your symptoms and conduct a physical exam. They may also order lab work and imaging tests.

 

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The liver helps you by taking toxins (substances in the body that are actually like poisons) out of your blood. Wait! Why do you have toxins in your blood in the first place? Sometimes your body produces them as part of its normal function, like breaking down protein, a component in foods such as meat and nuts.

The liver also cleans blood that has just been enriched with vitamins and minerals during digestion. After you've eaten something, the vitamins, minerals, and other nutrients from the food pass from the intestine into the blood. Before going out to the rest of the body, the nutrient-rich blood makes a stop at the liver.

The liver processes the good stuff into forms that the rest of the body can use. Waste or stuff your body doesn't need can be carried by bile back into the intestine and out of the body when you poop. Other waste processed by the liver goes through your blood to your kidneys and out in your pee. Your body’s biggest internal organ, the liver is like a complex chemical-processing plant. It converts nutrients from the small intestine into fuel your body can use. It makes bile, an essential substance for digestion.

And, if you ever accidentally ate something that was harmful, your liver would try to break it down and clear it out of your system. But don't put your liver to the test! Steer clear of poisons and other harmful stuff.

 

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Tonsils are small organs in the back of the throat. As part of the lymphatic system, they play an important role in the health of the body. Tonsils were once thought to be a useless part made obsolete by evolution. When bothered by an infection, doctors once prescribed the removal of the tonsils through a tonsillectomy. These small organs are actually quite useful, though. Though small and seemingly useless, tonsils have several uses. The tonsils prevent foreign objects from slipping into the lungs. Think of them as goalies for the throat. They also filter bacteria and viruses. These two meatball-shaped masses of tissue at the back of your throat are part of your lymph system, which includes a network of nodes that work like little security guards to battle infection.

 

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