polysaccharide digestion

Definition

Target type: biologicalprocess

The whole of the physical, chemical, and biochemical processes carried out by living organisms to break down ingested polysaccharides into components that may be easily absorbed and directed into metabolism. [GOC:go_curators]

Polysaccharide digestion is a complex process that begins in the mouth and continues in the small intestine. It involves the breakdown of large, complex carbohydrates into smaller, simpler sugars that can be absorbed by the body.

The process starts with the mechanical breakdown of food by chewing. This increases the surface area of the food, making it easier for enzymes to work on it. Salivary amylase, an enzyme found in saliva, begins the chemical digestion of starch, a type of polysaccharide, by breaking it down into smaller polysaccharides called dextrins.

Once the food reaches the stomach, salivary amylase is inactivated by the acidic environment. However, the stomach's churning action continues to break down food particles.

The majority of polysaccharide digestion takes place in the small intestine. Here, pancreatic amylase, an enzyme secreted by the pancreas, continues the breakdown of starch into smaller polysaccharides and disaccharides (sugars composed of two simple sugars).

The small intestine also contains enzymes called disaccharidases that break down disaccharides into monosaccharides (simple sugars). These enzymes include lactase (which breaks down lactose), sucrase (which breaks down sucrose), and maltase (which breaks down maltose).

The resulting monosaccharides, such as glucose, fructose, and galactose, are then absorbed into the bloodstream through the lining of the small intestine. They are transported to the liver, where they are used for energy or stored as glycogen.

Fiber, a type of polysaccharide that is not digested by humans, passes through the digestive system undigested. It provides bulk and helps regulate bowel movements.

In summary, polysaccharide digestion involves the following steps:

1. Mechanical breakdown by chewing
2. Chemical breakdown by salivary amylase in the mouth
3. Further breakdown by pancreatic amylase and disaccharidases in the small intestine
4. Absorption of monosaccharides into the bloodstream
5. Transport to the liver for energy use or storage'
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Proteins (8)

Compounds (40)