Human Body (Smart Lab)
Get ready for an incredible journey through your own amazing body!
Your body turns food and water into you: a living, growing person.
But how does your body change something like pizza into bones, muscles, and brain?
Let's follow a bite of pizza to help understand how all the parts of your body do their jobs.
MOUTH
1. It all starts in your mouth, where your teeth bite and crush the pizza into tiny pieces.
2. Enzymes in your saliva (spit) start digesting the pizza even before you swallow it.
STOMACH
Your stomach is a muscular sac big enough to hold a meal, even a whole pizza! it gets food ready for the body to use.
1. Muscles in the stomach wall squeeze food around to mix it.
2. Special cells along the sides of your stomach make a strong acid that breaks down the pizza even more. The acid dissolves the protein and the calcium from the cheese.
Cells are the building blocks of the entire body. Your body is made up of trillions of living cells. Cells are like tiny water balloons: each one is a soft sac filled with liquid. If you glued a pile of water balloons together, it would be solid, but squishy-just like your body!
3. Your stomach slowly squeezes out what's left of the pizza into the intestines.
(a) A layer of thick slime protects the stomach from its own acid. This is why the stomach doesn't digest itself.
(b) Feeling hungry? That's what happens when your stomach is empty. As you eat, your stomach stretches giving you that "full" feeling.
(c) What's happening when your stomach growls? Air and liquid squished through the system make a gurgling noise, like blowing through a straw into a glass of juice.
INTESTINES
Together, your small and large intestines are one long, squishy tube. One end is connected to the stomach, and the other end is connected to, well, your "other end".
1. The small intestine adds substances that make the stomach acid harmless to the delicate lining of the small intestine.
2. Enzymes in the small intestine break down all the nutrients into tiny molecules.
3. Fuzzy hairlike cells along the side of the small intestine, called villi (VIL-eye), absorb the nutrients and pass the along into your blood: protein from cheese, sugar from the crust, vitamins from the sauce, and fat from the oil.
4. Things like the tough fiber from the pizza's tomatoes are squirted into your large intestine. It absorbs much of the leftover water, leaving thick, brown POOP!
5. Bacteria in your large intestine feast on your poop.
LIVER
You can't LIVE without your LIVER! It's your largest internal organ and acts as the body's security guard.
1. All the blood from your intestines goes to your liver first. (The flow of blood starts at the bottom of this illustration).
2. Nutrients from the pizza go through your liver to get processed. The liver decides whether to store them or let them through, depending on what your body needs.
3. The liver keeps poisons, such as food preservatives, from going to the rest of the body.
4. When your liver is done, it sends the blood to your heart, so the nutrients from the pizza can be sent all over your body.
(a) The liver is dense with lots of blood flowing through it.
(b) Has your vomit ever been green? That's because of the bile. The liver makes bile, which helps digest fat. It is stored in the gall bladder until needed, then squirted into the small intestine. Subtances in bile can sometimes form hard lumps called gallstones.
(c)Because it stores nutrients, an animal's liver is one of the most nutritious meats you can eat.
KIDNEYS AND BLADDER
You have a pair of kidneys that are body's plumbing system. You can live with only one kidney. Drink plenty of water so your kidneys can do their job.
1. Blood flows into the kidneys for filtering. They can filter all of your blood as much as 400 times per day.
2. The blood is filtered through millions of tiny loops called nephrons (NEF-rons).
3. Ureters are tubes that carry urine (pee) from your kidneys to your bladder.
4. Your bladder stores urine until a convenient time for you to, well, pee. When it's about half full, you start to feel the urge.
5. You control a little muscle called a sphincter (SFINK-ter) at the bottom of the bladder to let out the urine when you're ready.
6. The urethra (you-REE-thra) carries the urine out of the body. The bladder relaxes, and you feel relief.
What you eat can come out in your pee. Eat red beets, and your pee will turn pink. Asparagus will make your pee smell like, you guessed it, asparagus!
DIAPHRAGM
The diaphragm is a thin, flat muscle located below your lungs in the rib cage. It is your most important breathing muscle. Its movement draws air into and out of your lungs.
1. The diaphragm's (DIE-uh-framz) movement draws air into your lungs. First, it tightens and gets flat.
2. The space in the rib cage is bigger and draws in air. This is you breathing in.
3. The diaphragm relaxes, and curves up under the ribs.
4. Air is let out of the lungs this is you breathing out.
Postscript:
(a) Watch someone's chest when they're breathing hard. When you are breathing really fast. Your Rib muscles help to lift the ribs up and draw more air into your lungs.
(b) What are hiccups? They are spams (sudden movements of the diaphragm. There are lots of ways people try to stop them, like holding their breath and counting to 10. But none of these tricks really work.
(c) Why do you get a pain in your side when you run too far? That pain is your side is pain in the diaphragm! It comes from not getting enough oxygen. It doesn't happen as much when you exercise regularly.
(d) So what does the diaphragm have to do with the pizza? The diaphragm is a muscle, and muscles are made of protein. Protein from the pizza's cheese will make your diaphragm strong. It takes energy to move muscles, and energy comes from the carbohydrates in the pizza crust.
HEART
Love your heart! It's a strong, thick muscle for pumping blood. Blood flows in the tubes all around the body, like a giant water slide!
1. Nutrients from the liver flow to the heart (The action starts at the bottom of the illustration).
2. The right side of the heart pumps blood through the lungs to pick up oxygen. Now the blood has both food and oxygen and is ready for the body to use!
3. The blood flows to the left side of the heart.
4. The left side of the heart is stronger because it needs extra power to pump blood way out to your fingers and toes. Whoosh! Now the pizza is headed out all over your body!
5. Arteries carry blood and oxygen to the body. Vitamin C from the tomato sauce keeps arteries and veins healthy.
6. Veins carry used blood back to the heart to get more oxygen from the lungs.
Postscript:
(a) Your heart is truly red. And it is about the same size as your fist. Blood is 83% water, make sure you keep enough in your system. Have a glass of water with your pizza!
(b) The liquid part of blood, called plasma, is clear. It's the doughnut-shaped red blood cells that make it look red. But if blood looks red, why do our veins look blue? Looking at them through layers of skin makes them look bluish.
(c) The plasma carries nutrients. The red cells carry oxygen. Other blood cells fight diseases and infection.
(d) Gross alert: Dont pick that scab! It's the body's own bandage. The clump of sticky, dry blood protects your cut while it heals underneath. It will fall off when it's done its job.
ESOPHAGUS and TRACHEA
Your mouth is used for breathing and eating, so how do air and food get to the right places? Your throat starts out as one tube and splits into two.
1. The mouth and tongue help you chew and swallow.
2. When you swallow, the epiglottis closes and covers the trachea, sometimes called the windpipe. The epiglottis is a piece of cartilage that stays open for breathing but closes off the trachea when you swallow. This trapdoor keeps food from going down the wrong tube.
3. Muscles push food and liquid down the esophagus to the stomach.
4. After you swallow, the tongue relaxes, and the epiglottis opens so you can breathe again
Postscript:
(a) What happens when something "goes down the wrong way"? If food or drink trickles down when the epiglottis is open, it gets into the trachea.
- Your body coughs to get it out. Cough is a powerful blast of air to clear something out of your trachea.
- A sneeze is like a cough, but directed out your nose to clear it. Can you sneeze with your eyes open? Most people can't.
(b) The voice box, or larynx, is located at the top of the trachea. Stretched along the sides are two little strands - your vocal cords. Vocal cords make sound to talk and to sing. When you tighten them and breath out, the air passes between the vocal cords, making them vibrate just like guitar strings.
(c) Boy's voices change when the voice box goes through a growth spurt. The vocal cords get thicker and longer, creating a deeper sound. Girl's voice boxes don't grow as much.
LUNGS
Lungs bring oxygen into the body. This helps burn carbohydrates from the pizza to make energy for living.
1. Oxygen comes from the air. The diaphragm contracts and draws air through the trachea and into the lungs.
2. The air ends up in tiny sacs containing alveoli (al-VEE-o-lie). the heart pumps blood to your lungs.
3. Blood flows closely around the sacs.
4. Oxygen passes through the sac wall into the blood. Oxygen is picked up by the red blood cells.
5. Blood goes back to the heart. The heart pumps the oxygen-rich blood all over your body.
Postscript:
(a) Why do colds give us super snotty noses? Viruses irritate the lining of the nose, so the nose makes extra mucus in an effort to wash away the irritating germs. But all that snot and sneezing just gives the virus a free ride to the next person.
(b) The Body's Exhaust System: The lungs provide another way for the body to remove waste they get rid of a waste gas called carbon dioxide. The gas passes from your blood into the air you breathe out. Keep your lungs clean! Dirt and smoke that get all the way into the alveoli can never get out. Both air pollution and cigarette smoke can cause lung disease.
(c) Your body has several ways to clean the air before it gets to your lungs: Nose hairs catch big particles, dust sticks to snot, sneezing blows it back out of your nose, coughing blasts it out of your throat.
SKIN, MUSCLES, BONES
1. Skeletal (voluntary): They move when you tell them to.
2. Cardiac (involuntary): Your heart muscle. You don't have to think about it. It always working.
3. Smooth (involuntary): These are mostly in your gut. They help you breathe and digest food without your having to think about it.
BRAIN
Your brain has many jobs. Thinking is one, but it also sends and receives messages.
Your brain uses neurons (NU-rons) to carry messages.
Neurons are tiny particles that are found throughout your body.
Messages travel through neurons sends a message to the neuron next to it. This goes on until the message gets to its destination.
The message might be "Ouch!" from stubbing a toe. Or it might be "I'm hungry. I'm going to reach for another piece of pizza."
