Journey of the Digestive System

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.

   Lets try an experiment, Shall we? 

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 starch.

 

For this I tried test I tried a piece of white bread.  I put a piece of bread on my tongue and waited for about 40 seconds before my mouth even began to salivate. I found that even after a minute I still was not getting any sweetness. After 3 minutes I began to salivate but not enough to tell the difference.  By now 5 minutes had passed and I was still not tasting sweetness.  I came to the conclusion that due to the medication I am on due to the surgery my taste buds may be a little off.

TIME:  5 minutes (Due to the medication I am on since my surgery a lot of foods have been tasting weird.)

Complete this chart.

  Enzyme             Producing Organ        Site of Action   Substrate(s)              

Salivary amylase	Salivary Glands	Tongue (Mouth)	Starch
Trypsin	Pancreas	Small Intestine	Protein
Lipase	Pancreas	Small Intestine	Lipid
Pepsin	Stomach	stomach	Protein

 

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?

          

•   Proteins: The digestion of protein entails breaking the complex molecule first into peptides, each having a number of amino acids, and then second breaking them into individual amino acids  

• Carbohydrates:  Carbohydrates are broken down in the digestive tract into the simple sugars, glucose, fructose, and galactose. The latter two can be converted by the body into glucose, which is distributed throughout the body via the bloodstream and is broken down into Carbon Dioxide and water in the mitochondria of cells.

• Fats: Fats are the most prevalent class of compounds (in living systems) referred to as lipids.  Fat molecules are characterized as monoglycerides, diglycerides, or triglycerides, depending on whether there are one, two, or three fatty acid chains present in the molecules.

     

1.      Describe the process by which fats enter the blood.  

       Hydrolysis of triglyceride into monoglyceride and free fatty

        acids is accomplished predominantly by pancreatic lipase. 

        The activity of this enzyme is to clip the fatty acids at positions

         1 and 3 of the triglyceride, leaving two free fatty acids and a 

         2-monoglyceride. Lipase is a water-soluble enzyme, and with a 

         little imagination, it's easy to understand why emulsification is a 

         necessary prelude to its efficient activity. Shortly after a meal,  lipase is present within the small intestine in rather huge quantities, but can 

         act only on the surface of triglyeride droplets. For a given volume of 

         lipid, the smaller the droplet size, the greater the surface area, which         

               means more lipase molecules can get to work.
         

Food Tracker       

 

For my Food Tracker I chose “My Recipe”.  I recently had major neck surgery (2 weeks ago) and I am finding it hard for me to find things I can eat without choking or having issues with swallowing.   With the recipes site I can put the type of food, either it be beef, fish, poultry or even soft foods like baby food and it brings up several recipes. The other thing I like about this site is that it allows me to put the number of portions I need.  I believe after things heal I will continue to use this site as there is a wide variety of items to choose from.