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?
- 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.
- 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. 
