Digestion and Absorbtion

• What is hydrolysis?


  Breaking bonds by adding water
• What is digestion


  Physical breakdown

  Chemical digestion
• Physical breakdown


  -Breakdown of food into absorbable nutrients

  - By teeth

  - Stomach muscles

  - increases SA
• Chemical digestion


  Hydrolyses large, insoluble molecules
• What is the importance of digestion?

  Hydrolyses large food molecules into smaller molecules

  Which can move across cell membrane

  And be absorbed into the blood
• Oesphagus


  carries food from mouth to stomach. adapted for transport. made up of a thick muscular wall
• stomach


  muscular sac between the oesphagus and the small intestine where digestion of food begins

  produces enzymes
• ileum


  Part of small intestine

  Long muscular tube

  Enzymes from walls and glands digest food

  Inner walls folded for large SA (have microvilli)

  
• large intestine


  Absorbs water and forms feces

  
• Rectum


  stores feces
• Salivary glands


  Contain amylase to hyrdolyse starch into maltose
• Pancreas


  Pancreatic juice (hydrolyse proteins, lipids and starch)
• Why are different enzymes needed to catalyse the breakdown of carbohydrates, proteins and lipids?


  Enzymes are proteins with specific tertiary structures

  Active site complementary to a specific substrate

  Only specific substrate will bind to active site and form E-S complex
• Where is amylase produced?

  Pancreas, salivary glands and small intestine
• Where is amylase secreted?


  Mouth and small intestine
• What is amylase for


  Hyrdolyses alternate glycosidic bonds of starch molecule to produce maltose
• Where is maltase produced?


  (In the cell membrane of epithelial cells)

  Small intestine
• Maltose


  glucose + glucose
• Where is maltase secreted?


  Small intestine

  (In the epithelial cells of the small intestine)

  Lining of ileum
• Role of maltase


  Hyrdolyses maltase into monosaccharide (alpha glucose)
• Process of carbohydrate digestion


  - Saliva breaks down and hydrolyses food to maltose (neutralises pH)

  - Acid in stomach denatures amylase preventing hyrdolysis of starch

  - Food into pancreas where pancreatic juices hydrolyse starch to maltose
• Process of carbohydrate digestion (muscles in intestine)

  Muscles in intestine wall push food along ileum

  Epithelial lining produces the disaccharide maltase (part of cell surface membrane of epithelial cells)

  MEMBRANE BOUND DISACCHARIDE
• Sucrase


  hydrolyses sucrose into glucose and fructose
• Lactase


  an enzyme that catalyzes the hydrolysis of lactose to glucose and galactose.
• What are the roles of the glands in the digestive system?

  To produce digestive juices
• Name two types of glands in the digestive system

  Pancreatic glands

  Salivary glands
• What is the function of the small intestine in the digestive system?

  It is where some digestion occurs and the absorption of soluble food also occurs
• What is the function of the stomach in the digestive system?

  It is where digestion occurs.

  It produces hydrochloric acid
• What is the role of the liver in the digestive system?

  It produces bile
• What are enzymes?


  Biological catalysts with a specific shape active site
• Where is lipase produced?

  Pancreas and small intestine
• Where is lipase secreted?


  The small intestine
• Role of lipase


  digests lipid molecules; necessary for the preparation of absorption of triglycerides

  Hydrolyses ester bond in triglycerides
• emulsification


  Breakdown of large fat globules into smaller, digestible particles (micelles)
• Where is protease produced?


  Stomach, pancreas and small intestine
• Where is protease secreted?


  Stomach and small intestine
• Different peptidases


  Endopeptidases

  Exopeptidases

  Dipeptidases
• Endopeptidase


  Hydrolyse peptide bonds between amino acids in central region of protein molecule

  Forms series of peptide molecules
• Exopeptidase


  Hydrolyses peptide bonds on end of peptide molecules (formed from endopeptidases)

  Remove single amino acids from proteins
• Dipeptidase


  splits dipeptides into amino acids

  membrane-bound as part of cell-surface membrane of il