Ask a Science Teacher: 250 Answers to Questions You've Always Had about How Everyday Stuff Really Works - Softcover

Larry Scheckel

Softcover

ISBN 10: 1615190872 ISBN 13: 9781615190874

Publisher: Experiment LLC, The, 2014

Synopsis

Fun and fascinating science is everywhere, and it s a cinch to learn just ask a science teacher! We ve all grown so used to living in a world filled with wonders that we sometimes forget to wonder about them: What creates the wind? Do fish sleep? Why do we blink? These are common phenomena, but it s a rare person who really knows the answers do you?All too often, the explanations remain shrouded in mystery or behind a haze of technical language. For those of us who should have raised our hands in science class but didn t, Larry Scheckel comes to the rescue. An award-winning science teacher and longtime columnist for his local newspaper, Scheckel is a master explainer with a trove of knowledge. Just ask the students and devoted readers who have spent years trying to stump him!In Ask a Science Teacher, Scheckel collects 250 of his favorite Q&As. Like the best teachers, he writes so that kids can understand, but he doesn t water things down he ll satisfy even the most inquisitive minds. Topics include: The Human Body Earth Science Astronomy Chemistry Physics Technology Zoology Musicand conundrums that don t fit into any categoryWith refreshingly uncomplicated explanations, Ask a Science Teacher is sure to resolve the everyday mysteries you ve always wondered about. You ll learn how planes really fly, why the Earth is round, how microwaves heat food, and much more before you know it, all your friends will be asking you!

About this title

About the Author

Larry Scheckel taught high school-level physics and aerospace science for over 38 years. He was named Tomah (Wisconsin) Teacher of the Year three times, and Presidential Awardee at the state level for six years. Scheckel has authored articles for The Science Teacher magazine and The Physics Teacher magazine, and for a number of years has answered science-related questions in the twice-weekly Tomah Times, out of which this book grew. Scheckel has been a Science Olympiad coach, robotics mentor, organized star gazing sessions, and given orientation flights to students, and he has given presentations to thousands of adults and students in such venues as Children's Museums, Boys and Girls Clubs, Rotary, and conventions.He lives with his wife in Tomah, Wisconsin.

Excerpt. © Reprinted by permission. All rights reserved.

ASK A SCIENCE TEACHER

250 Answers to Questions You've Always Had About How Everyday Stuff Really Works

By Larry Scheckel

The Experiment, LLC

Copyright © 2013 Larry Scheckel
All rights reserved.

ISBN: 978-1-61519-087-4

Contents

Preface, xvii, 
Chapter 1: The Magnificent Human Body, 1, 
Chapter 2: Wonders of Our Sea and Land, 75, 
Chapter 3: Science in the Sky, 105, 
Chapter 4: Technology, 147, 
Chapter 5: Stuff I Always Wondered About, 197, 
Chapter 6: Captivating Chemistry, 231, 
Chapter 7: The Strange World of the Atom, 259, 
Chapter 8: Science Through the Ages, 285, 
Chapter 9: Plants, Animals, and Other Living Things, 297, 
Chapter 10: Sound and Music, 323, 
Chapter 11: At the Fringes of Science, 333, 
Acknowledgments, 347, 
About the Author, 348, 

CHAPTER 1

TheMagnificentHuman Body

1. How many cells are in your body?

* There is no real consensus on the number of cells in the humanbody. Estimates put the number between ten trillion and one hundredtrillion. A trillion is a million million—it's a word that crops upwhen we talk about the size of our national debt! The number of cellsdepends on the size of the person: bigger person, more cells. Also, thenumber of cells in our body keeps changing as old cells die and new onesform.

Cells are so small that most can only be seen through a microscope.Every cell is made from an already existing cell. Each cell in the bodybehaves like a little factory and has two major components, the cytoplasmand the nucleus. The cytoplasm contains the structures that consumeand transform energy and perform many of the cell's specializedfunctions, including storing and transporting cellular materials, breakingdown waste, and producing and processing proteins. The nucleus isthe control center and contains the genetic information that allows cellsto reproduce. The mitochondrion (plural mitochondria) in the cell is thefactory where food and oxygen combine to make energy. Human cellsand other animal cells have a membrane that holds the contents together.This membrane is thin, allowing nutrients to pass in and wasteproducts to pass out. Food is the energy the cell needs. Each cell needsoxygen to burn (metabolize) the nutrients released from food.

The body has some cells that do not experience cell division. And redblood cells and outer skin cells have cytoplasm but do not have a nucleus.

In the cell, the process is called respiration. Oxygen breaks down thefood into small pieces. The oxidizing of the food molecules is turned intocarbon dioxide and water. Water makes up about two-thirds of theweight of the cell. The energy released is used for all the activities of thecell. The cell membrane has receptors that allow the cell to identify surroundingcells. Different kinds of cells release different chemicals, eachof which causes certain other types of nearby cells to react in certainways. Within each of these different cells are found twenty differenttypes of organelles, or structures.

Slightly over two hundred different kinds of cells make up the humanbody. The shape and size of each type of cell is determined by its function.Muscle cells come in many different forms and have many differentfunctions. Blood cells are unattached and move freely through thebloodstream. Skin cells divide and reproduce quickly. Some cells in thepancreas produce insulin, others produce pancreatic juice for digestion.Mucus is produced in cells in the lining of the lung. Our lungs also containalveolar cells that are responsible for taking in gas from the blood.The cells that line the intestine have extended cell membranes to increasethe surface area, helping them absorb more food. Cells in theheart have a large number of mitochondria to help them process a lot ofenergy, because they have to work very hard.

Nerve cells generate and conduct electrical impulses; for the mostpart, they do not divide. Each nerve cell has a specific place in our nervoussystem. Nerve cells outside of the brain are very long and have thetask of passing signals between the brain and the rest of the body, allowingus to move our muscles and sense the world around us. The rest ofour nerve cells—about one hundred billion of our body's cells—are braincells.

Brain cells are the most important cells in our bodies. It is our brainthat defines who we are. Brain cells in children under five do have theability to reproduce, to some extent. However, we are naturally losingbrain cells all the time. The best estimate of normal brain cell loss is putat nine thousand per day. That may seem like a large number, but rememberthat the brain has 100 billion cells, so a nine-thousand-cell lossper day is not that great. Inhalants, such as glue, gasoline, and paintthinner, cause brain cell loss at thirty times the normal rate. Excessivealcohol use is a big contributor to brain cell damage.

Cells that all do the same job make up tissue, such as bone, skin, ormuscle. Groups of different types of cells make up the organs of thebody. Different organs grouped together form a system, such as the digestivesystem or the circulatory system. All the systems working togethermake up a healthy human body.

Cells live, of course, but cells also die. Liver cells last about a year andhalf. Red blood cells live for 120 days. Skin cells are good for 30 days.White blood cells survive for thirteen days. And it turns out that thegreat majority of cells in the human body are bacterial cells, and mostare beneficial. It is hard to believe that the average adult loses close to100 million cells every minute. The good news is that the body, throughcell division, is replacing those lost 100 million cells every minute. Andin any case, even 100 million cells is only a small fraction of the trillionsof cells that make up our bodies.

2. Why do the young and the elderlyget sick more easily?

* Babies get sick more often than older children or adults becausetheir immune systems are not fully developed and functioning atfull capacity. The common cold, which is an infection of the respiratorysystem caused by a virus, is the most frequent malady. Doctors say thatnormal, healthy babies get up to about seven colds before they reachtheir first birthday. Another common affliction is the flu, caused by adifferent family of viruses, which bring on high fever, chills, fatigue, andsometimes digestive symptoms like vomiting and diarrhea, in additionto the respiratory symptoms of a cold.

Another reason babies get sick so often is that they are frequentlyaround other children, often siblings, and this exposes them to virusesand bacteria in school and daycare. Children in schools and daycare getmore colds, runny noses, and ear infections than children cared for athome. However, their earlier exposure to these diseases also leads themto develop immunity earlier.

Babies are also curious about the wide, wonderful world they areborn into. So they will stick anything and everything into their mouth asa means of exploring that world. You can imagine the enormous amountof germs that ride along.

Furthermore, babies have not developed the immunity to the manydifferent viruses that cause colds, because they haven't had time to acquirethe antibodies to fight off viruses. Babies do have some of theirmothers' antibodies when they are born, which were transmittedthrough the placenta during pregnancy. This kind of immunity isn't permanent,but breastfeeding can extend it, because many of the mother'santibodies are present in her milk. This is why breast-fed babies tend tohave fewer colds and flu symptoms than bottle-fed babies. Babies, likeother people, also develop their own antibodies in response to germsthey are exposed to; in fact, it's a mistake to try to eliminate all pathogensfrom a baby's environment.

Winter is the toughest time for babies, because it is the season whencolds spread nationwide. Also, in winter people spend more time indoors,where viruses are more likely to spread from one person to another.The less humid air of indoor heating dries nasal passages, whichallows viruses to thrive.

All people, both adults and children, are susceptible to bacterial andviral infections. Bacterial infections include meningitis, cholera, bubonicplague, tuberculosis, diphtheria, and anthrax. Vaccines for thesedreaded ailments were developed decades ago. But when the very youngand very old get sick, it is most often from viruses. A prime example isthe common cold.

There is no cure for the common cold, because many different virusescause colds and even if a medicine is developed for one of them, peoplewould still catch colds from other viruses. Many people who have colds, orwhose children have colds, ask their doctors for antibiotics, because theydon't understand that these drugs don't work against viruses. But there aremedicines that can relieve the symptoms of colds and flu so babies can getbetter sooner and not suffer as much. Recent research has developed medicinesagainst some viruses; for example, the vaccine that helps prevent theflu can also treat it if given soon enough after a person develops symptoms.

Elderly people get sick more often because their immune systems areweakened or breaking down. They also tend to have existing conditionsthat make them more vulnerable. Some have heart disease, kidney problems,asthma, diabetes, and a whole host of illnesses that no one looksforward to. Many of these diseases, as well as their treatments, suppressthe immune system.

That's why the Centers for Disease Control and Prevention (CDC)advises that children under five years of age and people over sixty-fiveyears of age have flu shots when each new strain begins to spread. Mostpeople who contracted the H1N1 swine flu virus in 2009 came downwith a mild illness, but the fatality rate was high. According to the WorldHealth Organization (WHO), 284,500 died from the H1N1 virus, themajority being from Africa and Southeast Asia.

3. What are birthmarks?

* A birthmark is a colored spot on or just under the skin. Most birthmarksshow up when a baby is born. Some are noticed shortly afterthe baby is born. Some birthmarks fade away as the child grows up, butsome stay and get bigger, thicker, and darker.

Nearly all birthmarks are harmless and painless. They can be almostany size, shape, or color.

Birthmarks have two primary causes: blood vessels that bunch togetheror do not grow normally and extra pigment-producing cells, ormelanocytes, in the skin. Doctors don't know what's responsible forthese two causes, but many think there is a genetic component involved.

The most common birthmark is the port-wine stain. The stain is usuallypink-red at birth and tends to become red or purple as a person ages.Port-wine stains, caused by blood vessels that do not grow normally, canhave various sizes and shapes. Port-wine stains most often show up onthe face, back, or chest. The strawberry birthmark is another that isfound on newborns. It is also caused by a clumping of blood vessels thatdo not grow normally. Mongolian spots are benign congenital birthmarksfound mostly on East Asians. Originating on the lower back, thesebluish spots disappear by the time the child reaches age five. A salmonpatch is a very common birthmark, occurring on 75 percent of newborns.It is caused by dilation of tiny blood vessels. Most salmon patchesdisappear by age one or two. Stork marks appear on the back of the neck,middle of the forehead, or upper eyelids. They vanish by the time thechild is two years old.

The downside of birthmarks is that kids have to live with the teasing,ribbing, and cruel remarks of classmates. Some kids can go through amiserable childhood enduring the slings and arrows of their peers. Butthere is some good news. Makeup creams can hide many birthmarks onthe face and neck or make them less noticeable. Others can be removedby surgery or lightened with a laser, but these treatments can be painful.Since most birthmarks are harmless, most are not treated.

4. Why is blood red?

* Blood is red because hemoglobin, a protein in red blood cells thatbinds oxygen and carbon dioxide, contains chemical compoundscalled hemes, and a heme is a blood pigment that contains iron, whichis reddish in color. There are about thirty-five trillion red blood cells—tiny,round, flat disks—circulating in our blood at any one time—that'sthirty-five followed by twelve zeroes. And each red blood cell typicallyhas more than 250 million hemoglobin molecules, each with four hemegroups!

Blood is pumped by the heart and circulated around the body throughblood vessels. Blood is bright red when the hemoglobin picks up oxygenin the lungs. The red blood cells carry the oxygen, bound to their hemoglobin,to the rest of the body through arteries and capillaries. Carbondioxide from the body's cells returns to the heart through capillaries andveins. The darker venous blood carries the carbon dioxide from the tissuesto the lungs, which expel them.

The blood coursing through our body's plumbing of arteries, veins,and capillaries contains many different materials and cells. Plasma, theliquid part of blood, is a light yellow color, denser than water, and carriesproteins, antibodies to fight diseases, and fibrinogen, which helps theblood clot. Plasma also has carbohydrates, fats, and salts. Young redblood cells mature in the marrow of the bone. Red blood cells have a lifeexpectancy of about four months. Then they are broken up in the spleenand replaced by new blood cells. New cells are constantly replacing oldcells. Our blood also contains several types of white blood cells. When agerm infects the body, some white blood cells race to the scene andproduce protective antibodies that overpower the germs, while otherwhite blood cells surround and devour them.

The average adult has between eight and twelve pints, or four to sixquarts of blood. If a person loses a significant portion of their blood supply,they go into shock and die. This can be prevented by transfusingblood from another person with a matching blood type (see page 13).The first blood transfusion on record took place in 1665. Richard Lowerof Oxford, England, took blood from one dog and put it in another dog.The first known human-to-human blood transfusion took place in 1795in Philadelphia.

5. Why are we attracted to unhealthyfoods?

* Some short answers: lots of junk foods have loads of sugar. Manyjunk food items are brightly colored, which attracts our (especiallychildren's) attention. People like finger foods, such as burgers, hot dogs,and fries. Advertisers target children, making junk food more attractivethan is healthy from a young age. Deep-fried foods are tastier than blandfoods, and children and adults develop a taste for such foods. Fatty foodscause the brain to release oxytocin, a powerful hormone with a calming,antistress, and relaxing influence, said to be the opposite of adrenaline,into the blood stream; hence the term "comfort foods."

We may even be genetically programmed to eat too much. For thousandsof years, food was very scarce. Food, along with salt, carbs, and fat,was hard to get, and the more you got, the better. All of these things arenecessary nutrients in the human diet, and when their availability waslimited, you could never get too much. People also had to hunt downanimals or gather plants for their food, and that took a lot of calories. It'sdifferent these days. We have food at every turn—lots of those fast-foodplaces and grocery stores with carry-out food.

But that ingrained "caveman mentality" says that we can't ever get toomuch to eat. So craving for "unhealthy" food may actually be our body'sattempt to stay healthy.

Food manufacturers put color additives in their foods. Bright, vibrant,saturated colors look more appealing to consumers. A bright redapple is more appealing than a dull red or green apple. A key to survivalin olden times was the ability to recognize foods that contained usableenergy or nutrition. People needed to be able to recognize foods thatcontained many calories, would support healthy brain function, harboredhealing medicines, and boosted the immune system. Many ofthose natural foods often appeared in bright colors, such as apples, oranges,bananas, carrots, and berries. Color was a reliable indicator of ahealthful food. Indeed, when apples, bananas, or berries spoil, they losetheir bright colors. So food-manufacturing companies are exploitingwhat was once a well-based notion that colorful foods are healthy foods!

Additives make foods taste better, look better, and last longer on theshelf. Experts agree that all those additives can't be good for us. Someadditives come from coal tar and petrochemicals. Our bodies are notmade to ingest crude oil. Some additives have been shown to be safe, butmany have not even been tested. There is growing suspicion that allthose additives are responsible in part for a rise in child obesity, attentiondeficit hyperactivity disorder (ADHD), and questionable behaviorpatterns. Some food dyes, such as Blue #2, Yellow #5, and Red #40, havebeen linked to cancer and ADHD.

(Continues...)

Excerpted from ASK A SCIENCE TEACHER by Larry Scheckel. Copyright © 2013 Larry Scheckel. Excerpted by permission of The Experiment, LLC.
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Edition details

• Publisher: Experiment LLC, The
• Publication date: 2014
• Language: English
• ISBN 10: 1615190872
• ISBN 13: 9781615190874
• Binding: Paperback
• Number of pages: 348