3. Leave about 3 lines for each.
Copy this chart into your journal. Take notes as we discuss each organ!
Leave about 3 lines for each.
Organ
Job
Mouth
Esophagus
Stomach
Small Intestine
Large Intestine

4. The process called digestion allows your body to get the nutrients and energy it needs from the food you eat.
Even before you eat, when you smell a tasty food, see it, or think about it, digestion begins. Saliva begins to form in your mouth. When you do eat, the saliva breaks down the chemicals in the food a bit, which helps make the food mushy and easy to swallow.

5. The esophagus is like a stretchy pipe that's about 10 inches long
The esophagus is like a stretchy pipe that's about 10 inches long. It moves food from the back of your throat to your stomach. But also at the back of your throat is your windpipe, which allows air to come in and out of your body.
When you swallow a small ball of mushed-up food or liquids, a special flap called the epiglottis flops down over the opening of your windpipe to make sure the food enters the esophagus and not the windpipe.
If you've ever drunk something too fast, started to cough, and heard someone say that your drink "went down the wrong way," the person meant that it went down your windpipe by mistake.

6. Once food has entered the esophagus, it doesn't just drop right into your stomach. Instead, muscles in the walls of the esophagus move in a wavy way to slowly squeeze the food through the esophagus. This takes about 2 or 3 seconds.
Your stomach, which is attached to the end of the esophagus, is a stretchy sack shaped like the letter J. It has three important jobs:
to store the food you've eaten
to break down the food into a liquidy mixture
to slowly empty that liquidy mixture into the small intestine

7. The stomach is like a mixer, churning and mashing together all the small balls of food that came down the esophagus into smaller and smaller pieces. It does this with help from the strong muscles in the walls of the stomach and gastric juices that also come from the stomach's walls. In addition to breaking down food, gastric juices also help kill bacteria that might be in the eaten food.

8. Did you know that the acid in your stomach is strong enough to dissolve small pieces of metal such as razor blades and
staples? The moment any object reaches the insides of your stomach they begin to be dissolved. That goes for meat, fruit and vegetables too. But if the stomach acid is so strong why doesn’t it eat your stomach away?
The stomach is covered with a thick coat of mucus. The cells in your stomach lining renew themselves every 3 to 4 days, giving you a new lining. So even though the acid does break down the lining of your stomach, your body protects you from serious damage by creating a brand new lining about twice a week.

9. The small intestine is a long tube that's about 1½ inches to 2 inches around, and it's packed inside you beneath
your stomach. If you stretched out an adult's small intestine, it would be about 22 feet long— that's like 22 notebooks lined up end to end, all in a row! Your food may spend as long as 4 hours in the small intestine and will become a very thin, watery mixture. It's time well spent because, at the end of the journey, the nutrients can pass from the intestine into the blood.

10. At 3 or 4 inches around the large intestine is fatter than the small intestine and it's almost the last stop on the
digestive tract. It is packed into the body, and would measure 5 feet long if you spread it out. After most of the nutrients are removed from the food mixture there is waste left over — stuff your body can't use. Before it goes, it passes through the part of the large intestine called the colon , which is where the body gets its last chance to absorb the water and some minerals into the blood. As the water leaves the waste product, what's left gets harder and harder as it keeps moving along, until it becomes a solid. Yep…it’s poop.

11. As your body performs the many functions that it needs in order to keep itself alive, it produces wastes. These wastes are chemicals that are toxic and that if left alone would seriously hurt or even kill you. The large intestine alone cannot remove all the waste that your body produces. The Excretory System (or urinary system) helps the body by cleaning toxins, including chemicals and excess salt, out of the blood.

12. The main organs of the Excretory System are the kidneys and the bladder. It only takes about 45 minutes for your kidneys to filter all of the blood in your body!

13. Other organs that help with digestion & waste removal
Liver –cleans your blood, produces an important digestive liquid called bile, and stores energy in the form of sugar.
Gallbladder – Stores extra bile which is a liquid that helps the stomach break down fats.
Colon – Part of the large intestine.
Other organs that help with digestion & waste removal
Add these 6 organs to your body model.
Be sure to label each one!
These should fit just below your respiratory system.

16. Did you know that biomedical engineers recently created the world's first artificial stomach? It mimics many of the activities that take place in your body and can even throw up!

17. You might be wondering what anyone would want to do with a machine that works like a digestive system and throws up on occasion. In reality, this machine is expected to be very beneficial to scientists, doctors and pharmacists who want to know more about how our bodies work. What happens to your food or medicine after you swallow it? How does your body absorb food or medicine into your system? This is very important to know!

18. Have you ever heard of a disease called diabetes
Have you ever heard of a disease called diabetes? You may know someone with this disease. When a person has diabetes, they are unable to process sugar when it gets into their blood, and this can lead to shock or even death if it is not regulated. One way this new machine benefits people is by helping doctors and researchers understand how fast certain foods are digested by the body and absorbed into the blood stream. This could lead to improvements in the understanding and treatment of diabetes.

19. Let me demonstrate how a biomedical engineer might use simulation (mimicking real life processes) to better understand how a medication is processed by the body. Let's use a simple model of the digestive system and represent the stomach by a cup filled with vinegar and the small intestine by a cup filled with water and baking soda.

20. We use vinegar to represent the stomach because it is an acid similar to the gastric acid that is squirted on food by our bodies while it is in the stomach. We use baking soda and water to represent the small intestine because together they form a base similar to bile, one of the main digestive juices squirted on food while it is in the small intestine.

21. What’s the difference between an acid and a base?
Wait!
What’s the difference between an acid and a base?

22. Let's test a medication that is commonly used to relieve pain or fever - aspirin. Unfortunately, aspirin can also make your stomach hurt. To keep this from happening, researchers developed several different types of coatings to keep aspirin from being digested until after it has passed through the stomach and into the small intestine. Let's do a quick test on one of these coatings to see how well it works.

23. Answer the following questions in your journal.
Why did we use different solutions to represent the stomach and the small intestine?
What did the demonstration show?
Why is this important for scientists to know?
Why might it be better for scientists to study new medicines in a simulated environment instead of with a person?

24. The Classifieds section of the newspaper is where people can purchase space to briefly advertise an item for sale or a service or item that is needed.

25. Write your own Classifieds ads describing, but not naming, parts the body systems we have studied.
Write an ad for each part of the digestive system. If you have time, you may also create ads for parts of other systems.
We will share some ads and determine which body part you need.
Ex. WANTED: a small, 4 chambered pump used to push fluid through a series of tubes. Must be reliable!