the human digestive system/enzymes

• a cell

  the basic building block of a living organism
• a tissue

  a group of cells with a similar structure and function working together e.g. muscular tissue contracts to bring movement
• an organ

  a collection of tissues working together to perform a specific function e.g. the stomach contains different types of tissues
• an organ system

  a group of organs working together to perform specific functions e.g. the digestive system
• function of the digestive system

  to digest food and absorb nutrients obtained from digestion into the bloodstream
• role of pancreas and salivary glands

  the pancreas and salivary glands are glands which produce digestive juices containing enzymes
• role of stomach

  produces HCl, which kills any bacteria present and provides the optimum pH for the protease enzyme to function
• role of small intestine

  site where soluble food molecules are absorbed into the bloodstream
• role of the liver


  produces bile; which is stored in the gallbladder; and emulsifies lipids to allow the lipase enzyme to work more efficiently
• role of large intestine

  absorbs water from undigested food, producing faeces
• role of enzymes

  act as a biological catalyst which speeds up the rate of biological reactions without being used up
• how does the shape of any enzyme affect its function

  lock and key substrate; enzymes have a specific active which binds to its complementary substrate
• how does temp. affect enzyme action

  increasing the temp will increase enzyme action as the molecules will have a higher kinetic energy

  above 37 degrees, the enzymes active site will alter and become denatured so it will no longer catalyse the reaction
• how does pH affect enzyme action

  optimum pH for enzymes is 7, if the pH is too extreme, the active site may be altered
• carbohydrases


  -amylase; salivary glands and pancreas

  -maltase; small intestine
• proteases


  -pepsin; stomach

  -others; pancreas and small intestine
• lipases


  pancreas and small intestine
• role of proteases


  break down proteins into amino acids
• role of lipases


  break down lipids into 1 glycerol and 3 fatty acids
• products of digestion


  used to build bigger molecules e.g. glucose in respiration
• role of bile


  -bile is an alkaline which neutralises stomach acids secreted by the stomach

  -emulsifies lipids to form droplets which increase the SA for lipase to work on