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Describe How Starch Is Digested in a Mammal. [5 Marks]

Question

Describe how starch is digested in a mammal. [5 marks]

Answer

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Verificación de expertos
Bernadette Master · Tutor for 5 years

Answer

Starch digestion in mammals takes a recursive journey beginning in the mouth, where salivary amylase in saliva starts the process by breaking down the large starch molecules. Digestion then resumes in the small intestine, courtesy of pancreatic amylase from the pancreas juices. Disaccharidases from the small intestine wall then breaks down the resulting disaccharides to monosaccharides, which are taken into the bloodstream.

Explanation

## Step 1: Starch digestion begins in a mammal's mouth. This is where salivary amylase, an enzyme contained in saliva, initiates the process. ## Step 2: Salivary amylase, breaks down large starch polymers into maltose, which is a disaccharide of two glucose molecules. ## Step 3:The bolus proceeds into the stomach, where it encounters a highly acidic environment. Te stomach has enzymes such as gastric amylase but it functions less optimally due to the acidic pH of the stomach environment. Stomach pH denatures salivary amylase and essentially stops the digestion process occurring from carbohydrate processing aspect. ## Step 4:The acidic (partly-digested starch) then proceeds from the stomach to the small intestine where a more alkaline environment is found. In the first section of the small intestine, (duodenum) the pancreatic juices are released. These juices contain an enzyme known as pancreatic amylase. ## Step 5:Pancreatic amylase picks up the work of the previously denatured salivary amylase and continues the work of braking down any remaining large starch molecules to maltose. ## Step 6:In the lining of the small intestines, the cells produce enzymes known as disaccharidases. These enzymes break down disaccharides to monosaccharides; for instance, maltase breaks down maltose to glucose. ## Step 7: Finally, the monosaccharides – made up of single sugar units such as glucose – are absorbed into the bloodstream via specialized cells in the wall of the small intestine.