Download Digestive system

topic: Body systems
activity: Digestive system
Students journey through the digestive system from chew to poo!
Suggested time: 30 minutes
Summary of Key Learning Points
Students:
- learn about chemical and mechanical digestion
- identify the importance of enzymes to digestion
- discover the organs of the gastrointestinal tract, their features and functions
- find out the difference between ingestion, digestion, absorption and egestion
- understand what an accessory organ is
The digestive system
5 minutes
Start by discussing with students their ideas about digestion. How would they define it? Come to a
consensus as a class about what digestion means. They can then select where they think it occurs in the
body and get different feedback messages for each part. After they select the first part, the rest of the text on
this page comes up.
Pushing the sandwich to the mouth brings up a close-up of the mouth. The Science extra allows students to
explore the major nutrient groups: vitamins, minerals, carbohydrates, protein, lipids (fats and oils) and water.
In the mouth
5 minutes
Students find out the difference between mechanical and chemical digestion using the Explore this. In the
mouth, both of these occur.
Answer:
Both (Inquiry point 1)
Talking point: What are the advantages of chewing food well? (Answer: Easier to swallow and increasing
the surface area allows the enzymes in saliva to break down any starch present.)
Selecting the ‘Next stop’ button allows the journey through the digestive system to continue.
© IntoScience 2014. This sheet may be reproduced for classroom use
Page 1/3
topic: Body systems
activity: Digestive system
In the oesophagus
5 minutes
The animation shows the bolus travelling down the oesophagus. Peristalsis actually occurs throughout the
gastrointestinal (GI) tract and is due to smooth muscle contraction.
Answers:
Yes (Due to peristalsis, you can swallow while upside-down, although it is not a comfortable thing to do)
(Inquiry point 2)
Peristalsis occurs in the: stomach; small intestine; large intestine (Inquiry point 3)
In the stomach
5 minutes
Explain to students what sphincters are and where they are located in the body.
Answer:
The strong acid in the stomach would attack the stomach wall if there was no mucus to protect it. (Inquiry
point 4)
Extra activity: Replicate stomach conditions in a beaker on a hotplate with a magnetic stirrer. Get students
to chew food then spit it into the beaker. Add acid until the pH of the solution is 2. Add a protease enzyme to
the mix then leave it at around 40 degrees Celsius for 2 hours. What does the mixture look like after that
time?
Talking point: What causes stomach ulcers? How has understanding of ulcers changed over the years?
Get students to look up Barry Marshall and Robin Warren (Nobel Laureates).
In the small intestine
5 minutes
Explain to students that if you unravelled the small intestine, the duodenum would be the first part and is
about 28-35 cm long. This is where most chemical digestion takes place. The jejunum, the next part, is about
2.5 m long. The last part, the ileum, is about 2-4 m long.
Students can select this organ to see an electron microscope picture of villi.
Answer:
© IntoScience 2014. This sheet may be reproduced for classroom use
Page 2/3
topic: Body systems
activity: Digestive system
A major job of the small intestine is to absorb nutrients into the bloodstream. A high surface area allows it to
do this. If the surface area was too small, many nutrients would pass through unabsorbed and be wasted.
(Inquiry point 5)
In the large intestine & beyond
5 minutes
Peristalsis in the large intestine is shown here. Ask students if they can spot the appendix!
Answer:
We would not be able to make certain vitamins and so our health could suffer. (Inquiry point 6)
Suggested completion levels
Basic – Inquiry point goal = 2
Students at this level will: define digestion and peristalsis; identify the difference between chemical and
mechanical digestion; describe the pathway of food in the body starting at the mouth and finishing at the
anus.
Core – Inquiry point goal = 4
Students at this level will: identify the difference between digestion and egestion; define peristalsis; compare
chemical and mechanical digestion; identify where the two types of digestion occur in the body; name all of
the organs involved in digestion and describe their functions.
Advanced – Inquiry point goal = 6
Students at this level will: define peristalsis, ingestion, digestion, absorption and egestion; compare chemical
and mechanical digestion; describe where chemical and mechanical digestion occur; identify the functions of
enzymes and villi; name all digestive organs, including accessory organs, and their functions; evaluate the
importance of the digestive system to life
© IntoScience 2014. This sheet may be reproduced for classroom use
Powered by TCPDF (www.tcpdf.org)
Page 3/3