What describes the process of starch digestion?

Starch digestion is a complex process that breaks down starch, a complex carbohydrate, into simple sugars. It involves several enzymes and occurs in both the mouth and the small intestine. Here's a step-by-step explanation of the process:

1. Salivary Amylase: The process begins in the mouth when saliva, which contains the enzyme salivary amylase, mixes with food. Salivary amylase breaks down starch into smaller molecules, such as dextrins and maltose. However, since the food remains in the mouth for a relatively short time, starch digestion in the mouth is limited.

2. Gastric Emptying: After chewing and mixing with saliva, the food is swallowed and enters the stomach. The stomach temporarily stores the food and mixes it with gastric juices, which contain hydrochloric acid and other digestive enzymes. The acidic environment in the stomach stops salivary amylase activity and denatures it.

3. Pancreatic Amylase: Once the stomach contents, now partially digested and acidic, enter the small intestine, several digestive enzymes from the pancreas are released. Among these enzymes is pancreatic amylase, which is the primary enzyme responsible for starch digestion. Pancreatic amylase breaks down dextrins and maltose (the products of salivary amylase activity) further into smaller sugars, primarily maltose and glucose.

4. Absorption: The products of starch digestion, mainly glucose, are absorbed into the bloodstream through the small intestine. Glucose serves as a source of energy for various cells in the body.

5. Small Intestine Enzymes: In addition to pancreatic amylase, the small intestine also produces other enzymes involved in starch digestion, including glucoamylase, maltase, and sucrase. These enzymes further break down dextrins and maltose into glucose and other simple sugars.

The complete digestion of starch into glucose allows the body to efficiently utilize the energy stored in carbohydrate-rich foods. If starch is not completely digested, it can reach the large intestine and be fermented by bacteria, potentially causing gastrointestinal symptoms like bloating, gas, and discomfort.