Where is starch digested

Chewing begins the gradual process of breaking down starch's long chains. As you chew, your salivary glands also activate, stimulating the production of saliva. But because food doesn't stay in the mouth for very long, these enzymes are only doing preparatory work.

The bulk of starch digestion is yet to come. When you swallow, food passes through your esophagus down to your stomach. It's here that starch digestion stalls because the low acidic pH of the gastric juice in your stomach mostly stops the salivary amylase — the enzyme that worked to break down food when it was in your mouth — from further breaking down starch, according to an October report in Current Diabetes Reports.

However, the stomach does work to physically mix and churn the food. Moving past the stomach, starch continues on to the small intestine. It's in this part of the digestive tract that the real action of starch digestion happens, per May research in Frontiers in Nutrition. When food now churned into a substance called "chyme" enters the small intestine, the pancreas releases its own digestive enzymes to help break down starch, says Frontiers in Nutrition 's research.

This enzyme enters the small intestine through the pancreatic duct and gets to work on deconstructing starch into smaller chains and individual molecules. In addition, the brush border of the small intestine contains other enzymes, such as maltase, sucrase and lactase, which also help with digestion and breaking down food, according to Colorado State University. Most carbohydrate digestion occurs in the small intestine, thanks to a suite of enzymes.

Pancreatic amylase is secreted from the pancreas into the small intestine, and like salivary amylase, it breaks starch down to small oligosaccharides containing 3 to 10 glucose molecules and maltose. The enzyme pancreatic amylase breaks starch into smaller polysaccharides and maltose. The rest of the work of carbohydrate digestion is done by enzymes produced by the enterocytes, the cells lining the small intestine.

When it comes to digesting your slice of pizza, these enzymes will break down the maltase formed in the process of starch digestion, the lactose from the cheese, and the sucrose present in the sauce. Maltose is digested by maltase , forming 2 glucose molecules.

Lactose is digested by lactase , forming glucose and galactose. Sucrose is digested by sucrase , forming glucose and fructose.

Action of the enzymes maltase, lactase, and sucrase. Recall that if a person is lactose intolerant, they don't make enough lactase enzyme to digest lactose adequately. Therefore, lactose passes to the large intestine. There it draws water in by osmosis and is fermented by bacteria, causing symptoms such as flatulence, bloating, and diarrhea.

By the end of this process of enzymatic digestion, we're left with three monosaccharides: glucose, fructose, and galactose. These can now be absorbed across the enterocytes of the small intestine and into the bloodstream to be transported to the liver. Digestion and absorption of carbohydrates in the small intestine are depicted in a very simplified schematic below. Remember that the inner wall of the small intestine is actually composed of large circular folds, lined with many villi, the surface of which are made up of microvilli.

All of this gives the small intestine a huge surface area for absorption. Digestion and absorption of carbohydrates in the small intestine. Fructose and galactose are converted to glucose in the liver. Once absorbed carbohydrates pass through the liver, glucose is the main form of carbohydrate circulating in the bloodstream. Any carbohydrates that weren't digested in the small intestine -- mainly fiber -- pass into the large intestine, but there's no enzymatic digestion of these carbohydrates here.

Instead, bacteria living in the large intestine, sometimes called our gut microbiota, ferment these carbohydrates to feed themselves. Fermentation causes gas production, and that's why we may experience bloating and flatulence after a particularly fibrous meal. Fermentation also produces short-chain fatty acids, which our large intestine cells can use as an energy source.

Over the last decade or so, more and more research has shown that our gut microbiota are incredibly important to our health, playing important roles in the function of our immune response, nutrition, and risk of disease. Membrane Transport 5. Origin of Cells 6. Cell Division 2: Molecular Biology 1. Metabolic Molecules 2.

Water 3. Protein 5. Enzymes 6. Cell Respiration 9. Photosynthesis 3: Genetics 1. Genes 2. Chromosomes 3. Meiosis 4. Inheritance 5. Genetic Modification 4: Ecology 1. Energy Flow 3. Carbon Cycling 4. Climate Change 5: Evolution 1. Evolution Evidence 2.