THE JOURNEY OF THE DIGESTIVE SYSTEM LAB (online)

Objectives:

1.       View the digestive system in action

2.       Investigate the action of salivary amylase in yourself

3.       Record information about digestive enzymes and their actions

4.       Answer basic questions about the anatomy and operation of the digestive system

5.       Create a Food Tracker plan for yourself.

Part 1. The Journey of the Digestive System

If you haven’t already, watch "The Journey of the Digestive System” at https://www.youtube.com/watch?v=e3O1AdlC8bI (5:08).

Part 2. Salivary Amylase and Other Digestive Enzymes

The digestion of a carbohydrate such as starch begins in the mouth where amylase produced by salivary glands is mixed with saliva.  Amylase is also produced by the pancreas and secreted into the duodenum.  In the presence of amylase, starch (a polymer of glucose) is hydrolyzed into the disaccharide maltose (a sweet sugar).  Maltose is later digested in the small intestine to glucose where it is absorbed.  Maltose, glucose, and other monosaccharides are known as reducing sugars. 

This can be demonstrated in a simple taste test.

1.       Place a crushed, salt free cracker or a small piece of bread or tortilla on the surface your tongue.  If salivary amylase breaks down the starch in the cracker to maltose, it should begin to taste sweet.

2.       Record the amount of time it takes to begin to sense a sweet taste instead of a starchy taste.

TIME: 1 min 15 seconds: it took me twice to taste the sweet, the first time it just got mushy so the second time I put it further back on my tongue and was able to taste the sweet.

  

Complete this chart.

Enzyme                                                  Producing Organ                     Site of Action                          Substrate(s)

Salivary amylase	Salivary Glands	Mouth	Polysaccharides
Trypsin	Pancreas	Small Intestine	Proteins
Lipase	Pancreas	Small Intestine	Triglycerides
Pepsin	Stomach	Stomach	Proteins

Questions

1.       Name the end molecules of digestion for each of the following types of food. In other words, what smaller pieces is each hydrolyzed into to be made available to the body?

a.       Proteins: The end molecule of proteins is Amino Acids.

b.      Carbohydrates: The end molecule of carbohydrates is monosaccharides.

c.       Fats: The end molecule of fats is chylomicrons.

2.       Describe the process by which fats enter the blood.  Bile salts emulsify lipids large fat droplets into smaller droplets so that lipases can digest the fats into fatty acids and monoglycerides. The fatty acids and monoglycerides dissolve in micelles composed of bile salts and lecithin. Micelles near the cells surface release their fatty acids and monoglcerides, which then diffuse across the cell membrane. In the cell the fatty acids and monoglycerides are re-synthesized to triglycerides and coated protein. The protein-coated yriglycerides are called chylomicrons. The chylomicrons exit the cell and enter a lacteal for transport to the blood. (Human Biology Concepts and current issues)

Part 3. Food Tracker

Visit this site https://www.supertracker.usda.gov/https://www.supertracker.usda.gov/and choose one of the six options on the homepage, Food-a-pedia, Food Tracker, Physical Activity Tracker, My Weight Manager, My Top 5 Goals, or My Recipe.

Participate in the activity and write a one paragraph description of what you did and your opinion of the activity.

I chose my weight manager as my activity.  I picked the maintain weight category to help me keep my weight as it is. After entering my information it gave me a routine of exercise and calories I should have on a daily basis.  I found it was interesting that I do not even eat close to the calories it showed I should be eating on a daily basis to maintain my weight. It also showed me the amount of food I should have per food category. I think this is a great tool for anyone who is looking at losing weight or just maintaining their weight.