Digestive System

• MOUTH - 1

  • chewing
  • increases surface area of food; makes digestion easier
  • saliva
  • contains amylase
  • digestive enzyme (breaks down starch -> glucose)
• PHARYNX (throat) - 2

  • receives food from mouth
  • site of swallowing
• OESOHPHAGUS - 4

  • carries food to stomach
  • muscular tube
  • food pushed through into stomach
  • through series of contraction - peristalsis
• STOMACH - 5

  • holds food
  • cells in lining of stomach
  • secrete hydrochloric acid
  • secrete pepsin - protease enzyme (protein -> amino acids)
  • walls of stomach protected by layer of mucus
• LIVER - 6

  • processes blood containing nutrients absorbed from small intestine
  • bile
  • made in liver
  • stored in gall bladder
  • neutralises stomach acid
  • emulsifies fat
  • increases surface area in small intestine
• GALL BLADDER -7

  • stores bile
  • awaits signal to move bile into small intestine
• PANCREAS - 8

  • creates digestive enzymes (break down protein, fats and carbohydrates)
  • secreted down pancreatic duct into first segment of small intestine
• DIGESTIVE ENZYMES

  • amylase; starch -> glucose
  • carbohydrase; carbohydrates -> sugars -> glucose
  • protease; protein -> amino acids
  • lipase; fats -> fatty acids + glycerol
• SMALL INTESTINE - 9

  • muscular tube
  • uses enzymes
  • from pancreas and liver
  • bile - neutralises acid
  • 3 parts
  • 1st - digestion
  • 2nd and 3rd - absorption
  • contents - semi-solid to liquid
  • breaks down large molecules into smaller ones
  • absorbed into bloodstream
• LARGE INTESTINE - 10

  • connects small intestine to rectum
  • processes waste
  • peristalsis (contractions)
  • absorbs water
  • stool
  • undigestable fibre and bacteria
  • when last section of large intestine becomes food of stool; contents are emptied into rectum
• RECTUM - 11

  • connects colon to anus
  • receives stool from large intestine
  • lets person know stool needs to be evacuated
  • holds stool until evacuation
  • relaxes during evacuation
• ANUS - 12

  • canal consisting of anus sphincters (muscles that line pelvis)