digestive system

• The human digestion system breaks down complex food substances and provides a large surface area for maximum absorption of food.
• label the poor chap

  A) mouth

  B) salivary glands

  C) oesophagus

  D) liver

  E) gall bladder

  F) small intestine

  G) stomach

  H) pancreas

  I) appendix

  J) large intestine

  K) rectum

  L) anus

  
• label da function

  A) carbohydrates

  B) protein

  C) carbohydrates

  D) protein

  E) lipids

  F) small intestine

  G) small intestine

  H) amino

  I) absorption

  J) amino

  K) glycerol

  L) absorption

  
• The surface of the small intestine wall is folded, and has projections called villi
• The epithelial cells that cover each villus themselves have projections called microvilli
• intestine

  A) small

  B) capillary

  C) villus

  D) villi

  
• oh!

  A) absorbed

  B) micro

  C) epithelial

  D) surface area

  E) capillary

  
• this diagram is called the lock and key theory

  A) substrate

  B) active site

  C) active site

  D) substrate

  E) catalyses

  F) substrate

  G) active site

  
• oh okay!

  A) proteases

  B) amino acids

  C) carbohydrases

  D) sugars

  E) lipases

  F) fatty acids

  G) glycerol

  
• to test for starch


  use iodine
• to test for protein

  use biuret solution
• to test for fats

  use sudan (III)
• to test for sugars

  use benedicts solution
• if starch is present, it will turn

  black / blue
• if protein is present, it will turn

  lilac
• if fats are present, it will turn

  orange at the top
• if sugars are present, it will turn

  orange after 5 minutes in hot water
• If the temperature of the surroundings is too high or low, the enzyme can be denatured
• When the active site changes shape, meaning the substrate won't fit, which causes reaction not to be catalysed, the enzyme has been denatured
• Bile is produced in the liver
• Bile is stored in the gall bladder
• Bile neutralises stomach acid in the small intestine, creating alkaline conditions. This is is important because enzymes in the small intestine work best in alkaline conditions
• Bile emulsifies fat, which gives fat a larger surface area for lipase to work on, making digestion faster
• Carbohydrate digestion begins in the mouth
• Amylase is produced by the salivary glands
• Amylase is produced in the mouth, small intestine and salivary glands
• Amylase converts carbohyrase into sugars
• Protein is digested in the stomach, where protease is produced
• Protease is produced in the stomach, small intestine and pancreas
• protease converts protein into amino acids
• the products of the digestive enzymes are absorbed into the bloodstream
• lipases convert lipids to fatty acids and glycerol
• lipase is produced by the pancreas and small intestine
• To test for protein:

  Grind up sample and put into beaker with distilled water and stir well. Filter using funnel and filter paper. Add 2cm^3 of the solution into clean test tube, and add 2cm^3 of Biuret solution. Gently shake the tube. If protein is present, it should turn from blue to purple.
• To test for reducing sugars (glucose):

  Add Benedict's solution to each tube using pipette. The place test tubes in a water bath at 75 degrees and leave for 5 minutes. Look for colour change and see the range of colours.
• When testing for glucose, it will turn traffic light colours depending on the concentration. Brick-red for the highest concentration