digestion

• digestion definition?

  where large molecules are broken into smaller ones that can be absorbed across cell membranes
• organs involved in the human digestive system-

  salivary glands, oesophagus, stomach, pancreas, small intestine, large intestine, duodenum, gall bladder, liver
• salivary glands -

  contains amylase for carbohydrate digestion
• oesophagus -

  muscles contract and squeeze the food down - peristalsis
• stomach -

  contains stomach acid which is the optimum pH for enzymes to work
• pancreas -

  enzymes secreted from here
• small intestine -

  (ileum) where digestion and absorption into the blood happens
• large intestine -

  where water goes back into the blood
• gall bladder -

  stores bile
• liver -

  produces bile
• duodenum -

  mixes bile and pancreatic enzymes to aid digestion
• examples of pancreatic enzymes?

  amylase, lipase
• starch digestion -

  starch hydrolysed into maltose by salivary amylase by breaking the glycosidic bonds

  pancreatic amylase continues to do this

  maltase (membrane bound dissacharide) hydrolyses maltose into a glucose molecules
• lactose digestion -

  lactase hydrolyses lactose into a glucose and galactose by breaking the glycosidic bonds between them
• sucrose digestion -

  sucrase hydrolyses sucrose into a glucose and fructose by breaking the glycosidic bonds
• where is amylase found?

  pancreas and salivary glands
• where is lactase and sucrase found?

  membrane of the ileum (small intestine)
• key parts of protein digestion?

  endopeptidases, exopeptidases, dipeptidases
• endopeptidase?

  hydrolyses peptide bonds between amino acids in the middle of a polypeptide chain
• exopeptidase?

  hydrolyses peptide bonds between amino acids at the end of polypeptide chains
• dipeptidase?

  hydrolyses dipeptides into single amino acids
• where are endopeptidases?

  stomach and pancreas
• where are exopeptidases?

  pancreas
• where are dipeptidases?

  epithelial cells of the ileum
• where is lipase produced?

  pancreas
• what bonds are hydrolysed in lipid digestion?

  ester
• what bonds are hydrolysed in protein digestion?

  peptide
• what bonds are hydrolysed in carbohydrate digestion?

  glycosidic
• what are the two ways triglycerides can be hydrolysed?

  into a glycerol and 3 fatty acids or a monoglyceride and 2 fatty acids
• role of bile?

  emulsifies fats into micelles which increases the SA to speed up enzyme action
• where is bile made?

  liver
• where is bile stored?

  gall bladder