LYCOS RETRIEVER 
Digestion: Stomach
built 629 days ago
Digestion of both types of starch--amylose and amylopectin--is initiated by salivary amylase during chewing and is stopped by gastric acid in the stomach. Starch is further digested in the duodenum by pancreatic amylase to maltose and isomaltose. These branch chain components are broken down to glucose molecules by enzymes called maltases, located in the microvilli of the intestinal absorbing cell. At the same time, ingested sucrose is broken down by sucrase to glucose and fructose.
Source:
Digestion, just like breathing, in greater or lesser degree, should be occurring all the time. Not just in the stomach, upper and lower intestine and pancreas, but as well in the blood stream.
Source:
Enzymes are crucial contributors to protein digestion. Protein-digesting enzymes are referred to as proteinases or proteases. Protein generally takes the form of very complex molecules arranged in chains of amino acids. So the bonds binding these complex molecules together must first be broken down. This digestive process begins in the stomach, where hydrochloric acid, secreted in the stomach's gastric acid, attacks the protein molecules separating them and breaking them down into amino acids. Then the gastric enzyme pepsin - the only protease able to digest collagen (the fibrous protein found in animal connective tissue) - starts to digest the amino acids.
Source:
Your body has an intricate protection from self-digestion by these enzymes. The stomach and intestinal tract lining have a mucous layer protecting the tissue from direct digestion by these enzymes. The pancreas uses other mechanisms for protection. Primarily, it produces the enzymes in an inactive form, called zymogens or proenzymes. For example, trypsin is produced as the inactive proenzyme trypsinogen. Trypsinogen is transported to the intestine where it is activated to trypsin by a protease enzyme on the brush border of the intestinal cells.
Source:
The high acid content of the stomach inhibits the enzyme activity, so carbohydrate digestion is suspended in the stomach. Upon emptying into the small intestines, potential hydrogen (pH) changes dramatically from a strong acid to an alkaline content. The pancreas secretes bicarbonate to neutralize the acid from the stomach, and the mucus secreted in the tissue lining the intestines is alkaline which promotes digestive enzyme activity. Amylase is present in the small intestines and works with other enzymes to complete the breakdown of carbohydrate into a monosaccharide which is absorbed into the surrounding capillaries of the villi.
Source:
If the food enzymes have been denatured or destroyed through a food processing method, only the enzymes in the saliva are available to begin digestion. Even after being chewed, some food pieces are still too large to pass through the wall of the stomach and intestines. They must be broken down into much smaller pieces.
Source:
MORE ABOUT
Stomach