Big Ideas: Circulatory System
Name: __________________ Block: __
The digestive system’s job is to help you take in and process food, extract the nutrients from it, The digestive
system works with the excretory system to remove the waste materials produced from processing the food.
Digestion involves lots of organs, and both mechanical, and chemical processes to complete their work. Taking in
the food is the beginning step of digestion.
You take in food and drink through your mouth. Food is assessed by your senses (nervous system) to
make sure it smells and taste good to you, and that It is not too hot to take in safely. Once the food is in your
mouth digestion begins. Your teeth crush, cut and grind your food into smaller pieces so that your body can
process it better. Also in the mouth digestive enzymes in your saliva begin to work on your food right away.
Enzymes are proteins that make it easier for a chemical reaction to happen. In your mouth a special enzyme
called amylase breaks starches down into the smaller simpler sugars they are made from.
When you swallow the food or drink is forced down your pharynx, past the epiglottis, into your
esophagus. The esophagus is a muscular tube about a foot long that connects to your stomach. As you swallow
the esophagus contracts behind the bolus (wad) of food, moving it steadily down into your stomach. This action is
known as peristalsis. In your stomach powerful acid, and more and different enzymes, like pepsin that breaks
down proteins, and bile from the gall bladder to digest fats, are added into the chewed food to form a slush
called chyme. Your stomach is made of muscles, and it contracts strongly to further crush and reduce the food.
When the stomach is finished with the food it moves toward the intestines. Just below your stomach is your
pancreas. The pancreas secretes insulin, a chemical that binds sugar so that it can be used by the body.
Sometimes people do not make enough insulin, a condition called diabetes, or too much at once, a condition
known as hypoglycemia, which leads to low blood sugar.
When food enters the small intestine it has been through both mechanical and chemical process to make
it easier to extract nutrients from. This is where real digestion begins- in the intestines. The food first moves into
the small intestine through the duodenum. In the small intestine millions of tiny fingerlike projections called villi
give the small intestine lots of surface area to extract and absorb the nutrients the body needs for food. The
nutrients then enter the blood stream through the walls of the small intestine. The small intestine is about
twenty feet long. When it is finished in the small intestine, the food travels to the large intestine. The large
intestine is only about five feet long, but much wider than the small intestine. By the time food reaches this point
almost all the nutrients have been extracted. At the end of the small intestine is the colon. The remnants of the
food here is waste material that the body needs to eliminate. Muscular contractions of the muscles here force
the waste material our through the rectum, the last straight portion of the large intestine. The anus is the
muscular sphincter that controls the final elimination of the waste remains of the food. Liquid waste is filtered
out of the bloodstream by the kidneys. There it runs through the ureters to be collected in the bladder, and then
eliminated through the urethra as urine.
Your body extracts four kinds of nutrients. The first is carbohydrates. These are sugars and starches,
mostly from vegetable and fruits you eat, that provide most of the actual fuel for your body. Your body also takes
proteins from animal flesh and some plants, like beans and soy. This provides your body with the building
materials you need to stay strong. Your body also extracts, and makes fats. Fat functions as a high energy storage
battery. Your body can burn fat as needed to provide it with extra energy. Lastly your body takes fiber out of
food. Fiber comes from plant material and you do not actually digest it. Instead, fiber travels through you
intestines and cleans them out.
Fill in the Blank!
Name: ________________________ Block: ____
1. The digestive system extracts ________________ from food.
2. The ________________ system removes waste from the body.
3. Digestion involves processes that are both ________________ and ________________.
4. Food is processed through your senses, like taste and ________________.
5. Your lips sample food to see if it is too ________________ to take in safely.
6. The ________________ is a muscular tube that connects your mouth to your stomach.
7. Once your teeth crush up food the enzymes in your ________________ go to work.
8. Starches can be broken down into ________________ by the amylase in your saliva.
9. The muscular contraction of your esophagus, or ________________, moves food into
your stomach.
10. ________________ is an enzyme that breaks down proteins in your stomach.
11. The stomach contracts powerfully on the food in it. The stomach also has acids and
enzymes at work. So in the stomach digestion is both ________________ and
________________.
12. Most of the extraction of nutrients from your food actually happens in your
________________ ________________.
13. The ________________ in your small intestine give it much more surface area.
14. Your digestive system extracts nutrition from ________________, mostly plant material,
________________, which are mostly from animals, ________________ that are high
energy storage, and ________________ that cleans out your digestive system.
Fact First Questions: Digestive System
Name: ________ Block: ___
1. Digestion is s process that takes place in more than one part of your body. Where does digestion
start?
2. Your body works to maintain a balance in the amount of sugar in your blood against the amount
of sugar you need to use. What organ secretes insulin to maintain this balance?
3. The small intestine is actually the longest part of your digestive system at about 21 feet. Why is
it called the small intestine?
4. The stomach is connected to the mouth by a tube ringed with muscles called the esophagus.
What do these muscles do?
5. Peristalsis is the process of the muscles of the esophagus contracting to push food to the
stomach. Can peristalsis go the other way?
6. The small intestine is lined with tiny fingerlike projections called villi. How do the villi help
digestion?
7. Your body does both mechanical and chemical digestion. What is the difference between the
two processes?
8. When you chew up food your saliva softens the food and starts the process of digestion. What
kind of food compound does saliva start digesting?
9. Your appendix actually has a purpose. What is that purpose?
10. Your intestines have a variety of different bacteria living there. Why is it important for you to
have these bacteria?
Thinking Map
Create a flow map of the process of digestion from the mouth to the …ah…final exit.
Special Assignment
Create a brochure model of the digestive system as a ride. Name your amusement park. Name the ride.
Label each part of the ride. Write a short account of riding the ride.
Fuel Up!
Across
2. Longest intestine, 21 feet of extracting nutrients.
3. Substance that breaks down fats.
6. Food tube takes the stuff to the stomach.
7. The process of breaking down food for fuel.
8. Breaking food down with acid and enzymes.
9. The shorter intestine, the one that gets rid of final solid waste.
Down
1. Tiny finger like projections that line the small intestine to increase surface area.
2. Glands that put liquid in your mouth that breaks down carbs.
4. Hollow sack that holds, and squishes food.
5. Type of digestion done by physically crushing food.