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ZatsWhy (Answers) - Our Amazing Bodies

Where is the gall bladder and what does it do?
Can I see a drawing of the human muscles with all the names?
Can you show me a drawing of the nervous system?
Why does our blood go around? Why do we have a heart in our body?
How does the heart make the blood move?
Why is blood blue when it's in your body and red when it touches the air?
How many pounds of blood do we have in our body?
How many times does the heart beat in a day?
Why do we burp?
How many bones are there in the human body?
How do scientists know what to name diseases like cancer?

Where is the gall bladder and what does it do?
The gall bladder is one of the parts of our bodies that scientists call “organs.” Our bodies are made up of lots of different cells, which do different jobs. Cells don’t work on their own, though. Cells that are alike and that all have the same job are often connected together in our bodies. First, they’re arranged in sheets called “tissues” which can be many cells long and wide, but usually not very many cells thick. (The tissues in the bathroom have that name because they also look like little sheets, long and wide but not very thick.). The cell tissues are grouped together into organs, so that the cells in the organs and tissues can all do their job together. So cells are grouped into tissues and tissues are grouped into organs. (Notice that this way that our bodies are arranged gives us a word we all know – when we group and arrange things together that belong together we say that they are “organized.”) The gall bladder is located just below the stomach and behind the liver. If you want to see a picture, here’s a link: http://www.cag-acg.org/patinfo/gall_bladder.htm. The gall bladder is not very big but it’s important because it helps us digest our food. When we eat, our bodies break down the parts of the food into fuel that our cells can use to make energy. (Scientists call this process of breaking down our food “digestion.”) Mostly, our bodies break down long complex groups of atoms in our food into simpler atoms that our cells can use. Fats are one type of fuel for our bodies, but fats are really big, long groups of atoms that our bodies have to break down to use. The liver (a very special organ in our bodies) makes a special combination of chemicals scientists call “bile.” Bile goes to work on fats we eat and helps to break them down into fuel for our cells. The bile the liver makes is watery and greenish yellowish in color, and it’s too watery to do the job of breaking down the fats very well. So the liver sends bile to the gall bladder. The gall bladder makes the bile stronger by drawing out some of the water in the bile while leaving the special combination of chemicals that works so well in breaking down the fats. (When a liquid is made stronger by taking water out of it, scientists say that the liquid is “concentrated.”). So the gall bladder’s job is to get the bile ready to break down the fats we eat and to put the bile into our system at the right time. After our food leaves the stomach, it goes into a long, tube-shaped organ called the “large intestine” and then into an even longer, tube-shaped organ called the “small intestine.” The large intestine and the small intestine is where a lot of our digestion happens. When our food gets to the small intestine, the gall bladder releases the bile it has been holding, and the bile goes to work to break down fats into the fuel that the cells in our bodies can use. The gall bladder’s job in just one small (but important) part of how our bodies work. Thanks for the question, Andrew.
by Jeff | Sat May 4 11:06:58 PST 2002 | Back to Top

Can I see a drawing of the human muscles with all the names?
Sure, Slim. Here’s a link to a good one: http://www.angelfire.com/scifi/Dree/Medical_Database/Muscular1.htm
by Jeff | Sun Feb 10 13:43:48 PST 2002 | Back to Top

Can you show me a drawing of the nervous system?
Sure, I can Larue. First, let’s learn a little bit about the nervous system, a very important part of how our bodies work. The nervous system is made up of special cells called nerves that form the communication system for your body. The system is made up of bundles of nerve cells that scientists call “neurons.” Nerves relay messages to your brain from your skin, your muscles, your eyes, ears, nose and tongue and most of the other parts of your body. Your nerves also transmit messages from your brain to your body. For instance, your brain sends messages through the nerves to your muscles to move your body around. Scientists call the one-way nerves that only relay messages from the body to the brain “sensory nerves” and they call the one-way nerves that only relay messages from the brain to the body “motor nerves.” Some nerves relay messages both ways. Scientists call these nerves “mixed nerves.” Most of the mixed nerves are in your spinal cord, but you have sensory nerves and motor nerves in all parts of your body. This link will show you how the nerves spread out all over the body. If you put your cursor on the little spots on the diagram, it will tell you the name of the nerve in the picture: http://www.innerbody.com/image/nervov.html. Here’s a link to a good animation of the nervous system: http://www.bbc.co.uk/science/humanbody/enhanced/index.shtml. If you want to know much more about nerves and how they work, here’s a link to a site with a lot of information: http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookNERV.html. (You might not be able to follow all of the terms and explanations on this one, but it has really good pictures and drawings of actual nerves!). The nervous system is very interesting, Larue. Thanks for asking about it.
by Jeff | Sun Apr 7 12:44:20 PST 2002 | Back to Top

Why does our blood go around? Why do we have a heart in our body?
Well, Brandon and Arian, you both asked the same question in two different ways. Our bodies are made up of tiny compartments called “cells.” The cells are like building blocks for the different parts of our bodies -- skin, bones, muscles, lungs, liver, brain, kidneys – all the different parts. Scientists call these different parts of our bodies our “organs.” The different types of cells in the different organs each have a job to do, and they are specially designed to do that job. For instance nerve cells relay messages to and from the brain and muscle cells make the muscle contract so it can do work. Each cell working away in the organs of our bodies is alive, and each cell needs oxygen and food energy to keep going. But they can’t take breaks! Instead, our bodies bring the cells oxygen and fuel through our blood. The heart pumps the blood down to the lungs where cells in the blood (called “red blood cells” or “red corpuscles”) pick up oxygen. The heart keeps pumping, and the red blood cells then go by our digestive system and get fuel from the food we eat. The heart keeps pumping and the blood cells go out into our bodies through smaller and smaller tubes (called “blood vessels”) until they get to the very smallest blood vessels (called “capillaries”). The capillaries are so small, they allow the blood cells to get right next to the individual cells in the body and deliver their fuel and oxygen to the hard-working cells. The heart keeps pumping and the red blood cells move through more blood vessels until they come back around to the heart. (Because the blood is moving in sort of a big circle from the heart to the lungs and digestive system then to the cells and then back around to the heart, scientists call the blood and the blood vessels the “circulatory system”) The heart then pumps the blood that just arrived back out to the lungs, and the whole process goes around again. So, we have a heart in our body to keep our blood moving constantly, and the blood goes around and around to provide our cells with the food and oxygen they need to keep doing their jobs. Great questions! Isn’t the human body amazing?
by Jeff | Tue Jan 15 10:46:03 PST 2002 | Back to Top

How does the heart make the blood move?
The heart is made of muscle just like the muscles all over your body, under your skin. Most of your muscles have the job of moving your bones around. They really only do their work one way, by pulling in or “contracting.” When they’re not working, muscles can relax and stretch. Muscles do their work together in pairs, taking turns pulling in and relaxing. For instance, one muscle contracts to pull your arm toward your body and then that muscle will relax and stretch to let another muscle contract and pull your arm away from your body. Usually muscles are shaped long and straight, like in your thigh, but your heart is a muscle with a very special shape. Your heart is made up of four smaller areas of muscle, each one shaped to have space in the middle, like a very small (but stretchy) cup. These little pockets of muscle are called “chambers.” The four chambers of the heart work in pairs -- the two on the left work together and the two on the right work together. Blood flows from the cells in the body into the chamber at the top of the heart on the right. (Scientists call this section the “right atrium”). The muscles of the chamber relax and it fills up with blood like a balloon. When the right atrium gets full, the muscles go to work. They pull in (“contract”) which squeezes the blood through a one-way door (called a “valve”) into the next chamber, right below it. While the right atrium is working, this lower chamber of the heart (which scientists call the “right ventricle”) relaxes and stretches and lets the blood fill it up like a balloon. Then, when it’s full, the left ventricle contracts and squeezes the blood out through a big tube to get it flowing to the lungs to get oxygen. The flow of blood then comes back from the lungs and goes into the chamber at the top left side of the heart (which scientists call the “left atrium”). The left side works pretty much the same as the right – the upper chamber squeezes the blood into the lower chamber (the “left ventricle”) and the lower chamber then squeezes the blood into a big tube (the “aorta”) to keep it flowing along. The difference is that the right side gets the blood from the cells in the body and pumps it out to the lungs and the left side gets the blood from lungs and pumps it out to the cells in the body. If you’d like to see a diagram, here are a couple of links: http://www.tmc.edu/thi/anatomy.html and http://www.thornes.co.uk/secondary/science/scinet/scinet/index.htm So your heart moves your blood because it is really like two pumps made of muscle, working side by side all the time. One pump moves the blood from the rest of your body to your lungs and the other moves the blood from your lungs to the rest of your body. Isn’t the human body amazing, Henry? Thanks for the question.
by Jeff | Sun Feb 10 13:49:48 PST 2002 | Back to Top

Why is blood blue when it's in your body and how do scientists know that your blood is blue if you can't see it when it touches the air?
Another good question, Sandra! Blood is very important to our bodies' functions for many reasons, but one of the biggest reasons is that blood carries oxygen to the cells in our bodies. Each cell in our bodies needs oxygen to make energy to do its job and to survive. There are cells in blood too, and these cells have a special coating called "hemoglobin" which allows them to carry oxygen to the other cells. Our heart pumps blood to our lungs and the blood picks up oxygen. When the hemoglobin has oxygen atoms attached to it, it turns red. The heart pumps the red (hemoglobin plus oxygen) blood out through a system of tubes called “arteries.” The tubes get smaller and smaller until they are so small that the blood cells have to squeeze through practically one at a time. (These really small tubes are called “capillaries”). The blood cells give up their oxygen to the cells and the blood without the oxygen looks blue. The blood then flows back to the heart to start the process over again. On the way back, the blue (hemoglobin minus oxygen) blood travels through a different system of tubes called “veins.” All the tubes for the blood, whether they are arteries, veins or capillaries, are known as “blood vessels.” Of course, when blood leaves the body, it looks red because the hemoglobin immediately picks up the oxygen in the air. Doctors know about the blue color of blood that has given up its oxygen by taking blood from a vein (rather than an artery) and drawing it into a test tube that doesn’t have air in it. Thanks for asking, Sandra, and “Shout out to Room 8.”
by Jeff | Thu Jan 3 17:09:21 PST 2002 | Back to Top

How many pounds of blood do we have in our body?
Thanks for asking, Juan. Usually people only talk about blood in terms of it's "volume," which is the measure of how much space blood takes up. What you want to know is how much blood weighs. For both measures, the answer depends on how big the person is because bigger people have more blood. In terms of weight though, anyone's blood makes up about 7% of their body weight. So if you weigh 80 pounds, your blood's weight would be 80 times 0.07 or a little over five and a half of your eighty pounds (5.6 pounds, really). For someone who weighs 200 pounds, the weight of their blood would be 200 times 0.07 or about 14 pounds. Fun question!
by Jeff | Tue Dec 11 22:44:18 PST 2001 | Back to Top

How many times does the heart beat in a day?
The answer depends on the person, Anna. A little baby’s heart is smaller and it has to beat more often to do its job of moving the blood around the baby’s body. Women are often smaller than men, so their hearts tend to be smaller and to beat more often than many men’s hearts do. When we exercise, we increase the need in our cells for energy and oxygen. The heart pumps faster during exercise to move the blood around faster to bring more energy and oxygen to the cells. So the heart beats more often in a day with a lot of exercise than it does on a day of just sitting around. (For the same reason, our hearts beat slower when we sleep because our bodies are resting and not making such a big demand for energy and oxygen.) If a person exercises a lot, his or her heart gets strong, and it can move more blood with fewer beats. The hearts of people who are physically fit beat fewer times in a day. Lots of other things, like age and body size and emotions can affect how fast or slow our hearts beat, so the best we can do is to get a general idea of how many times a person’s heart might beat in a day. Usually, the number of times your heart beats is measured in how many times it beats per minute (which scientists call our “heart rate”). A little baby’s heart rate is between 90 and 140 beats per minute. An adult’s heart rate is more likely to be about 72 beats per minute. We can figure out how many beats in a day using multiplication (a very important skill in life). Multiplication allows us to figure that if we counted 72 beats of an adult person’s heart every minute for an hour and then for all 24 hours in a day, we would count 103,700 beats in a single day. If we did the same thing for a baby, the baby’s heart might beat between 130,000 and 201,000 times in a day. So, you can be pretty sure that your own heart is beating between 100,000 and 200,000 times every single day. In one day it can move 4,300 gallons of blood! Did you ever imagine that your heart worked so hard for you every day?
by Jeff | Sun Feb 10 13:45:12 PST 2002 | Back to Top

Why do we burp?
Burps come from our stomachs sometimes after we eat. When we eat or drink, our stomachs go to work, using special acid to break down the fuel in our food into forms that our bodies can absorb and use. This whole process of breaking down our food is called “digestion,” and the work our stomachs do on our food is an important part of digestion. Burps are releases of gas that has built up in our stomachs during digestion. The gas can build up in our stomachs three ways. First, we often swallow a little air along with our food when we eat. Second, the food or drink itself might have gas in it (Have you noticed that you burp more when you drink soda? That’s because the soda has gas in it, of course. You can see and feel the bubbles!) Third, the acid in our stomach can have a chemical reaction with some types of food, releasing gas as a part of the reaction. If the gas builds up enough to push on the inside of our stomachs, we can feel it as pressure or even discomfort. We burp to release this gas – and we usually feel much better! It’s natural to burp, but if you’re around other people it’s best to cover your mouth and say “Excuse me” after. Fun question, Jennifer. Thank you.
by Jeff | Fri Jan 25 11:25:17 PST 2002 | Back to Top

How do scientists know what to name diseases like cancer?
Scientists usually try to name a disease after some symptom of the disease to make it easier for other scientists to correctly identify it when the symptom appears. If a disease causes a lot of symptoms to happen all together, the name of the disease sometimes has the term “syndrome” attached to the end. Although this idea for naming diseases is a good one, it’s more like a guideline than a rule. Diseases are sometimes named for the scientist who discovered them or for the place where the disease was first discovered (like Dutch Elm disease, which was first found in elm trees in Holland, for instance). Because names based on scientists’ names or place names don’t really help later scientists to understand anything about the disease, scientists these days try to use names based on the disease symptoms. Also, disease names used to use a lot of words in Latin, a very old language that was very popular with scientists for a long time but which no one really uses to speak to each other anymore. Latin is still important in science, but names for new diseases these days try to use more common terms. Here’s the story on cancer in particular. Our bodies are made up of tiny compartments called “cells.” The cells are like building blocks for the different parts of our bodies -- skin, bones, muscles, lungs, liver, brain, kidneys – all the different parts. Each of our cells has a code inside it (called “DNA”) that tells the cell what to do and how and when to make a copy of itself. Normal cells make a copy of themselves every now and again by first making a copy of their DNA and then splitting right down the middle so each half has a copy of the directions! When the DNA of a cell is damaged, the cell can begin to make copy after copy of itself without stopping. This alone can be a problem in the body but it’s even worse because each of the cells the damaged cell makes have the same mistakes in their DNA. These damaged cells don’t do their jobs in the body and they can begin to stop other, healthy cells from doing their jobs as well. The area of damaged cells grows and grows and causes swelling around the area. Scientists call this swelling a “tumor.” Scientists call a disease “cancer” if it makes a tumor in the body and stops the other cells from doing their jobs in the body. The word “cancer” is the Latin word for “crab” and scientists probably picked this term because the tumor holds on tight to the area of healthy cells it is hurting, sort of like a crab holds tight with its claws. Good question, Sandra. Keep going at this rate and one day we’ll have to call you “Dr. Sandra”!
by Jeff | Tue Jan 15 12:01:25 PST 2002 | Back to Top

What is WhyizZat all about?

WhyizZat is a fun site to learn about science and ask science questions. My name is Jeff, and I have been interested in science since I was in about the 4th grade. I like all kinds of science subjects, including how our bodies work, what makes up the world around us, what the stars and planets are like. I'm not a scientist myself, but I've learned a lot about science and what I don't know I can usually find out.

- Jeff Koppelmaa