Digestion

• What is digestion?

  The process in which large, insoluble molecules are hydrolysed by enzymes to produce smaller, soluble molecules that can be absorbed and assimilated
• What is chemical digestion?

  hydrolysis reactions
• What is mechanical digestion?

  The physical breakdown of large molecules into smaller sections (e.g. actions of the teeth and stomach churning)
• Why are different digestive enzymes produced in different parts of the digestive system?

  They require different optimum PH
• What are the two types of amylase?

  Salivary amylase - starch digestion occurs in the mouth

  Pancreatic amylase - starch digestion occurs in the small intestine
• What occurs in starch digestion?

  • Chewing stimulates the secretion of amylase from the salivary gland
  • In the mouth, the glycosidic bonds in starch are broken in hydrolysis reactions catalysed by amylase, to form maltose (disaccharide)
  • In the small intestine, the glycosidic bond in maltose is then broken in a hydrolysis reaction catalysed by maltase (a membrane bound dissacharidase) to form alpha glucose
  • This glucose is soluble and can be absorbed across the gut wall into the blood via cotransport
• Where is maltase found?

  The cell membranes of epithelial cells in the small intestine