Glucose is a carbohydrate that is an important structural component of many biological compounds. Digestion is a necessary process that breaks down food into smaller molecules of nourishment, which can be used to sustain cell growth and provide energy for the body. The digestion of carbohydrates involves the conversion of polysaccharides into smaller compounds such as glucose, a simple sugar. Digestive enzymes play an important role in the breakdown of glucose.
Oral Digestion
Digestive enzymes break long biological compounds into smaller molecules that can be more easily absorbed into the bloodstream. The digestion of carbohydrates begins in the mouth. The process of chewing, known as mastication, helps break food down. Saliva contains an enzyme, amylase, which is the starting point of the breakdown of complex carbohydrates. Once food is swallowed, it travels down the esophagus and into the stomach where the next step of digestion begins.
Stomach Digestion
The enzymatic breakdown of carbohydrates is continued in the stomach. Glands in the lining of the stomach release digestive enzymes. The pH of the stomach is also an important factor in the digestive process. A pH of approximately 2 allows adequate digestion of carbohydrates and other molecular compounds such as proteins.
Small Intestine Digestion
The majority of nutrient absorption occurs in the small intestine. Once the carbohydrate compounds enter the small intestine, the pancreas releases additional enzymes. These enzymes are responsible for the breakdown of carbohydrates into simple sugars such as maltose, lactose and sucrose. As the food products travel through the small intestine, maltase, lactase and sucrase are released. These additional enzymes aid in the breakdown of maltose, lactose and sucrose into glucose. The glucose passes through the intestinal walls and is absorbed by the bloodstream.
Liver Metabolism
Once glucose is absorbed into the bloodstream, it is transported to the liver, where it is either distributed to cells throughout the body or stored for future use. The liver is responsible for monitoring and regulating the body's glucose levels. If blood sugar levels are too high, excess glucose will be converted to glycogen and stored. If blood sugar levels drop, the hormone glucagon will convert glycogen to glucose in order to provide energy to cells.
The Speed of Carbohydrate Digestion
The speed of digestion is based on the molecular structure of the carbohydrates. Simple sugars, such as glucose, are less resistant to starch and are digested and metabolized quickly. Consuming many simple sugars provides a quick source of glucose and energy. Additional molecules, such as fiber, are more complex structures and can slow the absorption of glucose and other carbohydrates.
References
- National Institute of Diabetes and Digestive and Kidnety Disease; Your Digestive System and How It Works
- "The Journal of Clinical Pathology"; Carbohydrate Digestion and Absorption; R. Holmes; May 1971
