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LESSON I:
ANATOMY OF THE DIGESTIVE SYSTEM
To Address NYS Standards:
5 (Organisms maintain a dynamic equilibrium that sustains life)
Behavioural Objective:
The students will be able to recall the major organs of the digestive system and their
functions.
Explanation of Lesson Plan:
This lesson will familiarize students with the “big” picture of the digestive system, and
will allow them to learn the major organs of the system, along with what each organ does.
This will set up the students for a more in-depth discussion of how the system works in
future lessons.
Hook: (3 minutes)
Beakers will be set up on the front bench. One will have 1,200 mL of water and 800 mL
of a solid, to represent daily intake. Another will have 2,000 mL of coloured water to
represent gastric secretions. 500 mL for bile, 1,500 mL for pancreatic secretions, and
1,500 for small intestine secretions. Then, 8,100 mL for blood absorption. The last
beaker will have 100 mL of water and 50 mL of solids to represent waste.
Totals: 2,000 mL of stuff in from food, 7,000 mL of stuff in from body, and 8,100 mL in
nutrients into blood. Pretty amazing!
Test of Prior Learning: (3 minutes)
1. What does your digestive system do?
2. How do other digestive systems work?
New Learning: (30 minutes)
1. The purpose of the digestive system is to absorb nutrients from ingested material.
2. Note, we do not say “food.” Bunnies eat their own droppings, called copophagy.
Fungi digest stuff outside their cells, and then absorb it. Cows eat grass, but actual
bacteria does the digestion. “Food” is to vague a term.
3. The mouth chews the food, and starts carbohydrate digestion.
4. The pharynx is the very back of the mouth, leading to the esophagus.
5. The esophagus moves food down to the stomach. The top 1/3 is voluntary, the bottom
2/3 are involuntary.
6. Stomach starts protein digestion and destroys bacteria. Mechanical digestion as well.
7. Small intestine absorbs nutrients and moves food along. Duoudenum, jejunum, ileum.
About 3 m in length.
8. Large intestine desiccates feces and stores it. About 1 m in length.
9. Rectum stores feces
10. Anus controls defication.
11. There are several organs through which food does not pass, but which are very
important.
- the liver produces bile, bicarbonate, and secretes organic waste to be deficated.
- the gall bladder stores bile
- the pancreas produces enzymes and juices.
12. There are three phases of digestion.
- Cephalic: The sight or smell of food, or emotions.
- Gstric: stuff in the stomach stimulates functions
- Intestinal: distention of intestine, osmolarity regulation
13. These are controlled by the somatic nervous system, as well as the enteric nervous
system.
Test of New Learning: (3 minutes)
1. How do enzymes work?
2. Is bile an enzyme? Mechanical or chemical break down?
Assignment: