Amazing Kids! Magazine

Answers to the Most Interesting Body Questions

By Sean Traynor, Editor-in-Chief

The body is an amazing set of complex mechanisms.  It also does some quirky things that make us wonder, “Why does it do that?”  This article will help clear up some of the mysteries of the body that you always wonder about.

Why do I get goosebumps when I’m scared?

Goosebumps are bumps on a person’s skin at the base of body hairs that raise up involuntarily when a person is cold or experiences strong emotions such as fear or awe.  In humans, we can have this response by listening to beautiful music, hearing nails on a chalkboard or experiencing strong emotions such as winning an important spelling bee.  This reflex is known as horripilation or the pilomotor reflex.  It occurs in many mammals such as porcupines, which raise their quills when threatened.  Goose bumps are created when tiny muscles at the base of each hair contract and pull the hair erect.  The sympathetic nervous system creates this fight-or-flight response as a reflex.  When animals that are covered with fur or hair become cold, the hairs trap air to create a layer of insulation. The trapped air can also make the animal appear larger, to scare off enemies.

 

What are hiccups?

Hiccups occur when a spasm contracts the diaphragm, which is a large dome-shaped sheet of muscle that separates the chest cavity from the abdominal cavity.  This spasm causes an intake of breath that is suddenly stopped by the closure of the vocal cords. The vocal cords are what make the sounds you use to speak.  This closure causes the “hiccup” sound.  This spasm is caused by an irritation. It can be caused by eating too much food too quickly, an irritation in the stomach or the throat, swallowing too much air, a sudden change in stomach temperature (such as drinking a hot chocolate and then eating ice cream), or emotional stress or excitement.  Although hiccups usually stop within a few minutes to a few hours, there are some home remedies for getting rid of them.  By increasing the carbon dioxide in the blood, the hiccups will usually stop.  This can be done by holding your breath and counting slowly to 10, breathing repeatedly into a paper bag for a short period of time, or quickly drinking a glass of cold water.  Some people say that placing a teaspoon of sugar under your tongue or eating some honey also does the trick.  Others insist that being scared will chase them away.  Interestingly, hiccups affect males more often than females.  However, every human being gets hiccups, even babies.  So the next time you get hiccups, concentrate on your diaphragm and see if you can more clearly feel what is happening.

 

Why do I get a headache when I eat or drink something cold fast?

Have you ever gotten a shooting pain when you’ve taken a big sip of your Icee or eaten a large spoonful of ice cream?  A possible reason is the cold reacting with a sensitive bundle of nerves above the roof of your mouth, deep in your skull.  It reacts to the cold food or drink by causing blood vessels to dilate rapidly, sending a shooting pain through your head. Though the sensation goes away quickly, you can prevent this by beginning to consume cold items slowly so these nerves can get used to the temperature. It may also help to warm items up in your mouth first, before swallowing.

 

Why do I get a big rush when I eat candy and then I feel tired very soon afterwards?

Candy contains sugar molecules, which are quickly absorbed into the body.  Unlike proteins and starches, which are absorbed more slowly, sugar takes less time to be absorbed, causing a “sugar rush” from the energy.  But energy from sugar is also used up quickly.  When your energy is low, you get tired.  The energy you get from proteins and starches is absorbed more slowly, so it lasts longer and you do not get tired as quickly.

 

Why does human skin come in different colors?

There are numerous varieties of skin tones among human beings.  Although scientists have a theory as to why differing skin tones developed in different parts of the world, no one knows for sure.  Our apelike ancestors were covered with a thin coat of hair, which protected their skin from the sun. As humans evolved, they were born with less hair on their body.  The darker skins had a survival advantage over lighter skinned humans.  So over time, the darker skin was passed to the new generations.  As humans migrated north, into a colder climate, the sunlight was weaker, requiring lighter skin to survive.  The darker skin would have blocked out much of the needed UV, causing health problems like rickets.  UV light is necessary for the body to build up tough, straight bones and so the body would adapt to the new climate with new generations having lighter skin in the colder areas.  Therefore, skin tones reflected the climates people settled into – the lightest skin in the very weak sun of Scandinavia, golden-to-medium brown skin in sunnier climates, darkest skin among such groups as Africans and Australian Aborigines.  Now people can move freely and quickly from place to place, resulting in a blend of skin tones around the globe.

Skin tone depends on melanin, a chemical- the more melanin in our skin, the darker the color of the skin. As we sit in the sun, our skin produces more melanin and becomes “tan”.  Making more melanin is the skin’s way of defending itself against ultraviolet radiation from the sun, which can cause skin cancer. Melanin absorbs UV radiation and helps to protect the skin against further damage. The more melanin the skin has, the better its protection from UV rays.

 

Why are people’s eyes shaped differently?

No two people look exactly alike.  Certain groups of people do share some similar features, however.  Everyone’s eyeballs are shaped very much the same, but the skin around their eyes may be different.  Asian people have a fold of skin over the corner of their eyes called an epicanthic fold.  They also carry more fat and so are thicker than the eyelids of most Europeans or Africans. The fold and the thicker lid mean that more of the eyeball is covered. Scientists believe that this is due to a combination of similar facial characteristics such as high cheekbones and flatter noses that helped them adapt to the extremely cold air. As this group of Asians crossed over the frozen Bering Strait onto the continent of North America, they settled farther south.  You can now see their facial characteristics in Native American Indians, Alaskan Eskimos, Peruvian Indians, and Fiji Islanders.

Today you see a blending of facial characteristics in any continent caused by the ease of travel and movement by virtually everyone in the world.

 

Why do people get seasick or carsick?

Don’t you just hate that queasy, tired or dizzy feeling you sometimes get when you ride in a car on a windy road , when you ride in an airplane that is changing directions or when you are sitting inside your cabin on an ocean liner?  Why does that feeling come from?

This uneasy feeling is caused by the difference between what we feel and what we see when we are in a moving vehicle.  The motion is registered inside your ears, as the fluid in your inner ears shifts with the motion.  Your ears signal your brain that you are moving but to your eyes, the area around you appears to be still. Your eyes send this information to your brain and the mismatch of information causes the brain to panic.  You can also get skin receptors telling your brain which parts of your body are touching the ground and muscle and joint sensory receptors that tell your brain if you’re moving your muscles and which position your body is in.  If these are not telling the brain the same story, stress hormones, such as adrenaline, start pouring into your body. The stomach muscles get stimulated, causing them to contract faster than normal, sometimes making you vomit.

Don’t worry – motion sickness is very common.  9 out of 10 people get motion sick at least every now and then. To lessen the feeling, don’t travel on an empty stomach.  Eat a small meal.  In a car or bus look out the window and look at things far away or down the road so the messages from your ear and your eyes are the same. On a boat, go to the top deck in the middle and look at the horizon (where the sun and sky meet.) Always face forward in a moving vehicle. There are motion sickness drugs, but they can make you feel drowsy, dizzy or queasy.  Only take medicine under adult supervision.  Finally, what works for me is “sea bands.”  These are elastic bands, which you put on your wrists where a plastic button presses down on a special spot, using acupressure to lessen the feeling of motion sickness.   If you’re in a place where you already have motion sickness, pull over and walk around a bit.  This will settle your stomach and send consistent signals to your brain.  Always keep a plastic bag handy, just in case!

 

Why does hair turn gray?

Just like our skin, hair is colored by a chemical called melanin.  Gray hair is hair that is not getting its supply of melanin. Hairs grow out of special tubes in the skin called follicles. Follicles are made of skin cells, which absorb the melanin. The melanin supply decreases in two ways:  The melanocytes in skin cells make less melanin or the melanocytes tentacles that reach the hair cells to give them the melanin shorten so that they no longer reach them.  Melanocyte production slows as we grow older and the hair turns white, the natural untinted color of the keratin protein that makes up a strand of hair. The hair is not actually gray, it is a mixture of dark and white hairs, creating an optical illusion of gray, like a salt and pepper mixture.  Although blond hair is most likely to go totally gray, gray hairs are more noticeable in dark hair.  So, what age will you start to go gray?  This is mostly affected by genetics, or what happened to your parents. Other things do effect the age, such as lack of B-12, certain diseases such as malaria, typhus, diabetes, overactive thyroid gland, certain kinds of radiation, or even the flu.

 

Why do I yawn?  Why do I yawn when someone else yawns?

When we yawn, the head tilts back, the jaw drops, the eyes squint and the brow wrinkles.  A yawn briefly stops oxygen-carrying blood from leaving the brain, helping us to wake up and also calm down.  Most people think that we yawn in order to take in more oxygen, but psychologists have studied this and proven that people given pure oxygen yawn just as much as those who aren’t.  The cause of yawning is not known.  Many other animals yawn too.  Fish, lions and other creatures can be seen yawning at regular intervals.  Monkeys and lions yawn when they are hungry while Siamese fighting fish yawn when they are ready to attack.

We have not determined why humans yawn, but we sure do copy each other when we do.   They also have not determined the exact reason for this but researchers assume it stems from when early humans lived in groups and the group’s behavior was more synchronized.  Yawning then may have signaled something to the other members of the group such as feeding time or bedtime.  Some day maybe we’ll know the exact answer but, yawn, now it’s time to go to bed!

 

Why does my stomach growl when I’m hungry?

When all the food is gone from your stomach or intestines, air fills those parts of your body.  Your stomach and intestines move all the time.  This movement causes the air to move around, causing a rumbling sound.

 

Why does my foot fall asleep sometimes?

When you don’t move for a while or put weight on your feet, less blood flows to the feet. Your feet’s nerves are long and thin and they get squished easily.  When less blood flows into your feet, less oxygen is carried there.  The muscles of that body part get weak and the nerves begin to lose their feeling. This is when your feet feel as if they are “asleep.”  When you move your foot again, the nerves go back to their normal shape and blood rushes to that body part.  Sometimes this sends sharp stabs of pain that feel like needles.  It passes quickly though.

 

Why are bruises black and blue?

When you run into something, it can break the tiny capillaries under your skin.  When capillaries are broken, blood leaks out and fills the area that is around them.  Oxygen can’t reach the red blood cells because your capillaries are damaged.  When red blood cells are without oxygen, they turn blue.  So, the area that is bruised is “black-and-blue” because it does not have any oxygen.

 

Why do I sweat when I get hot?

When you are hot, your brain sends a message to the blood vessels in your skin to open wider.  The blood vessels carry heat from deep inside your body to your skin.  As the heat is released through your skin, the outside air cools it.  This quick cooling causes sweat.  The sweat helps to cool your body when the sweat evaporates.

So the next time you find your body doing something interesting, go to the library and see why it does it.  The cool functions of the body are like an intricate mystery novel just waiting to be solved.  You’ll enjoy learning more about the body.