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# 5.3: Activities and Answer Keys

Difficulty Level: At Grade Created by: CK-12

## Activity 4-1: A Journey through the Intestine (Peristalsis)

### PLAN

Summary Students make a model of an intestine out of polyethylene tubing. They simulate peristalsis by filling the tube with an oatmeal mixture representing chyme. Using their hands to simulate muscles moving the chyme through the tube, they demonstrate the most efficient method that moves food and wastes through the intestine.

Objectives

Students:

$\checkmark$ define the term peristalsis.

$\checkmark$ explain the importance of peristalsis.

$\checkmark$ demonstrate the muscle movements necessary to move food mixtures (chyme) through the digestive tract.

$\checkmark$ describe the physical structure of the intestine and how it promotes absorption of nutrients.

Student Materials

• Activity Report
• Tubing (2-inch diameter); Simulated chyme (cooked oatmeal/rice); Coloring material; Selected food items (grapes/lettuce); Bucket of water and paper towels; Water bottle; Spoons; Gloves; Funnel with large opening

Teacher Materials

• Materials for simulated chyme-Rice mixture: 2 cups water, 1 cup rice, 3 teaspoons salt; Oatmeal mixture: 6 cups water, 2.5 cups oatmeal, 5 teaspoons salt
• Diagram or model of the digestive system

Prepare the simulated chyme. This can be stored in the refrigerator for a few days. Apportion chyme in plastic zip-lock bags, one for each student lab group. Order tubing. Cut one piece of tubing for each lab team. Purchase any additional "roughage" food items, such as grapes or lettuce.

Estimated Time One 45-50-minute class period

Interdisciplinary Connections

Health Discuss the effects of alcohol, drugs, and coffee on the small intestine.

Arts Make a cloth or wooden model of the digestive tract, possibly showing the inside of the intestine with its muscular layers and villi that help absorption.

Prerequisites and Background Information

No special knowledge is required, though familiarity with the parts of the digestive tract would be helpful. Peristalsis is wavelike muscular contractions of the digestive tube propelling chyme through to the colon. Circular and longitudinal smooth muscles control the diameter and the length of segments of the intestines. Peristalsis moves chyme along the intestines and rubs it against the wall so digested molecules can be absorbed. A large surface for absorption ensures adequate nutrition. Patients with shortened intestines (e.g., resulting from surgery) can become malnourished because of inadequate absorption. Acetyl-choline stimulates peristalsis and, in excess, can cause diarrhea. Norepinephrine slows peristalsis. Paregoric, an opiate, paralyzes peristalsis. In contrast to the migrating rings of peristalsis in the intestine, colonic movements are to and fro. Colonic movements occur more frequently in the ascending than in the transverse colon and facilitate the absorption of water. An increased number of squeezes at one end moves chyme along the colon. Students can mimic these movements (called haustral shuttling or mass movements) at the aboral (anal) end of their long tube model.

Chyme can be whitish yellow at the start and then turns stool color later, after the duodenum, because bile enters. Black stools come from stomach bleeding because hemoglobin acted on by stomach acid turns black.

### IMPLEMENT

This activity works well when each lab group has a set of materials at the lab station. However, if time is limited, this activity is also a good demonstration. You might have several students do the demonstration under your guidance.

Introduce Activity 4-1 by demonstrating it.

Steps 1-6 Students can use their peristalsis models to simulate the actions of certain drugs, such as acetylcholine (to speed up peristalsis), norepinephrine (to slow peristalsis), or paregoric (an opiate that paralyzes peristalsis).

Extend Activity 4-1 by encouraging students to perform research about disorders of the intestine and the effects of drugs.

You may want to demonstrate how to fill and squeeze materials through the tube before students begin working with their own lab groups.

• To save time, you can fill up the tubes for students ahead of time.
• Chyme can be simulated with oatmeal or rice.
• Use one quart of chyme material for each 3-foot length of tubing.
• The following combination of rice and oatmeal makes about 9 cups of chyme (4-5 demos). Each team of two will need approximately 2 cups or about 420g, e.g., 9 cups chyme = enough for 4-5 teams of 2 students.

$&\text{Rice}: && 8 \times 2 \ \text{cups} \ H_2O = 16 \ \text{cups} \ H_2O\\&&&8 \times 1 \ \text{cup rice} = 8 \ \text{cups rice}\\&&&8 \times 3 \ \text{teaspoons salt} = 24 \ \text{teaspoons salt}\\&&&\text{makes}\ 24 \ \text{cups cooked rice}\\&\text{Oatmeal}: && 8 \times 6 \ \text{cups} \ H_2O = 48 \ \text{cups} \ H_2O\\&&&8 \times 2.5 \ \text{cups oatmeal} = 20 \ \text{cups oatmeal}\\&&&8 \times 5 \ t \ \text{salt} =40 \ t \ \text{salt}$

• Roll of polyethylene tubing may be purchased from

Gillis & Lane, Inc. (packaging co.)

830 2nd Ave.

Redwood City, CA

(650) 367-9900

Fax #: (650) 367-7580

(8-12, 1-5: M-F)

Flat Tubing part # RTN MIL 02

$12''$ diameter rolls: $2''$, as folded and collapsed

$2''$ mill 2,150 linear feet/roll

Need 2-3 days notice plus time for mailing

### ASSESS

Use the completion of the simulation and written responses on the Activity Report to assess if students can

$\checkmark$ explain the process and importance of peristalsis.

$\checkmark$ demonstrate how food moves through the intestine.

$\checkmark$ describe the composition of chyme.

$\checkmark$ explain how nutrients are absorbed by the small intestine.

$\checkmark$ explain how certain drugs can affect the digestive tract.

## Activity 4-1: A Journey through the Intestine (Peristalsis) – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. Which type of hand movements were most effective in mixing and moving the chyme along the tube?
2. Describe what happened when you added the coloring agent and the food item.
3. Design a follow-up activity to extend your knowledge of peristalsis. (Use the back of this sheet if necessary).

What Passes across a Membrane? Students determine the sizes of four molecules-water, glucose, an amino acid, and starch-based on their ability to pass through different membranes with different-sized pores. They answer a series of questions to help them reach and justify their conclusions.

## Activity 4-2: A Journey through the Intestine (Villi)

### PLAN

Summary Students investigate the structural and functional characteristics of the small intestine through observations of an animal's small intestine. They explore how to increase surface area, make a model of the human intestine, look at slides of cross sections of intestines, and measure a rectangular area representative of the surface area of the small intestine.

Objectives

Students:

$\checkmark$ describe the function and structure of the small intestine.

$\checkmark$ explain the function and structure of the villi of the small intestine.

$\checkmark$ observe the intestinal structures of different animals.

$\checkmark$ calculate the surface area of the small intestine.

$\checkmark$ explain the relationship between surface area and the efficient absorption of nutrients.

Student Materials

• Activity Report
• Slides of intestine showing villi, and epithelial cells. (Electron micro-graphs of microvilli from textbooks); Microscope; Model or diagram of human digestive tract; Corrugated box cardboard; Sheep, pig, or cattle intestine; Butcher paper and/or adding machine paper; Scissors, markers, tape, ruler; Calculator; Scalpel or razor blade; Gloves (latex or plastic)

Teacher Materials

• Model or diagram of human digestive tract

Order the intestines (pig, sheep, or cattle) from a packinghouse or a local grocery store or butcher. Order the microscope slides of the intestine. Buy adding machine paper or cut strips of butcher paper. Collect corrugated cardboard and string.

Estimated Time Two 50-minute periods

Prerequisites and Background Information

It is helpful if students know how to calculate the circumference of a circle although it is possible to learn about the concept of surface area of the intestines without having this skill.

A videotape titled Design for Living emphasizes the efficiency of the human body. One particular sequence shows the villi and how their structure provides a large surface area for efficient absorption of nutrients. Films for the Humanities and Sciences, Inc., Box 2053, Princeton, NJ 08543

### IMPLEMENT

Introduce Activity 4-2 by reviewing safety rules for working with dissection specimens. Wear gloves as you set up the necessary equipment.

Day 1

Steps 1-2 Cut sections of the intestine just before passing them out to students for dissection. The yellowish fluid, the chyme, oozes out of the ends and starts to dry up. Set up all the necessary equipment for the dissection of the intestine.

Rinse and pat dry the intestine. Then cut it into pieces of desired lengths.

Step 3 Set up microscopes for viewing slides of the cross sections of the intestinal tissue.

Day 2

Steps 4-6 Make available the materials for the intestinal model. Cut squares of corrugated cardboard of approximately $7 \ cm \times 7 \ cm$.

This activity goes hand in hand with Activity 4-1: A Journey through the Intestine (Peristalsis).

### ASSESS

Use the completion of the activity and written responses on the Activity Report to assess if students can

$\checkmark$ describe the structure and function of the small intestine, including the villi.

$\checkmark$ relate the total surface area of the intestine to the total number of villi present.

$\checkmark$ explain how the folded structure of the villi increases the surface area available for food absorption.

$\checkmark$ explain the relationship between surface area and the efficient absorption of nutrients.

$\checkmark$ build a model and calculate the surface area of the small intestine.

## Activity 4-2: A Journey through the Intestine (Villi) – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. How does the inside surface of the intestine feel? Why?
2. Describe and sketch the corrugated cardboard square both before and after it has been flattened.
3. How is your intestinal lining like the cardboard? Why is this important?
4. What do you think would happen if part of the approximately 5-meter-long small intestine were removed?
5. Draw 3 or 4 of the villi that you see under the microscope. How are they designed for efficient nutrient absorption?
6. It has been said that the small intestine is an engineering masterpiece. Explain.
7. Many animals, like wolves, have a keen sense of smell. They have many more sense receptors than dogs, yet their noses are similar in size. How can all those receptors fit into a limited space?

A suggested response will be provided upon request. Please send an email to teachers-requests@ck12.org.

Why do health workers not just run water into your blood through the IV?

Drawing the Actions of the Digestive System Students create three drawings of the actions of the digestive system that are analogous to the steps involved in recycling old cars.

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. What is peristalsis and how does it help you process food in the small intestine?
2. What is the role of the small intestine in digestion?
3. When a person has had his or her gall bladder removed, which digestive process will be affected? How will that process be affected?
4. What is bile? What role does it play in digestion?
5. Why don't the digestive enzymes of the pancreas digest the pancreas?
6. What is osmosis?
7. Why is the liver important? Explain five important functions of your liver.

## Activity 4-1 Report: A Journey through the Intestine (Peristalsis) (Student Reproducible)

1. Which type of hand movements were most effective in mixing and moving the chyme along the tube?

2. Describe what happened when you added the coloring agent and the food item.

3. Design a follow-up activity to extend your knowledge of peristalsis. (Use the back of this sheet if necessary.)

## Activity 4-2 Report: A Journey through the Intestine (Villi) (Student Reproducible)

1. How does the inside surface of the intestine feel? Why?

2. Describe and sketch the corrugated cardboard square both before and after it has been flattened.

3. How is your intestinal lining like the cardboard? Why is this important?

4. What do you think would happen if part of the approximately 5-meter-long small intestine were removed?

5. Draw 3 or 4 of the villi that you see under the microscope. How are they designed for efficient nutrient absorption?

6. It has been said that the small intestine is an engineering masterpiece. Explain.

7. Many animals, like wolves, have a keen sense of smell. They have many more sense receptors than dogs, yet their noses are similar in size. How can all those receptors fit into a limited space?

6 , 7 , 8

## Date Created:

Feb 23, 2012

Apr 29, 2014
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