Digestion of Starch in the Digestive System

• Amylase breaks down starch to maltose

Salivary Amylase

The digestion of starch begins in the mouth. Salivary glands secrete an enzyme called salivary amylase into the saliva.

As we chew food, salivary amylase starts breaking down the long chains of starch molecules into smaller fragments, primarily maltose. Maltose is a disaccharide composed of two glucose molecules linked together.

Pancreatic Amylase

After swallowing, the food travels down the esophagus and reaches the stomach. Here, salivary amylase activity is halted due to the acidic environment of the stomach.

The partially digested food, called bolus, moves from the stomach to the small intestine. In the duodenum (the first part of the small intestine), the pancreas secretes pancreatic juice, which contains pancreatic amylase.

Pancreatic amylase continues the breakdown of starch into maltose, completing the conversion of starch into maltose.

• Maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine:

The small intestine has millions of tiny finger-like projections called villi, which are covered with even smaller hair-like structures known as microvilli. These structures form the brush border on the surface of the epithelial cells lining the small intestine.

Maltase Enzyme

Maltase is an enzyme present in the brush border of the small intestine. It specifically acts on maltose and breaks it down into two glucose molecules.

Maltose Digestion

As chyme (partially digested food) enters the small intestine, it comes into contact with the brush border of the epithelial cells.

Maltase in the brush border catalyzes the hydrolysis of the bond between the two glucose molecules in maltose, resulting in the release of two separate glucose molecules.

Absorption of Glucose

The now broken-down glucose molecules are small enough to be absorbed through the lining of the small intestine. They move through the epithelial cells and enter the bloodstream, where they are transported to various tissues and organs in the body.

The absorbed glucose molecules can then be used as a source of energy by the body’s cells or stored for later use.