digestive system

• tongue/mouth

  • breaks down large pieces of food
  • physical and chemical digestion
  • produces amylase
• salivary glands

  • secretes amylase
• oesophagus

  • carries food from the mouth to stomach
• liver

  • processes nutrients absorbed by the small intestine
  • secretes bile into small intestine
• gall bladder

  • stores and concentrates bile
• stomach

  • stores and digests food
  • physical and chemical digestion
  • produces HCl and protease
• pancreas

  • produces pancreatic juice
  • produces amylase, protease, lipase
• large intestine

  • absorbs water
  • chemical digestion
• small intestine

  • food is further digested by enzymes
  • chemical digestion
  • releases bile, amylase, protease, lipase
• carbohydrases = type of digestive enzyme that hydrolyses carbohydrates
• lactase = produced by the epithelial lining and is a membrane bound disaccharidase which breaks down lactose into the monosaccharides by glucose and galactose
• maltase = produced by the epithelial lining and is a membrane bound disaccharidase which breaks down maltose into glucose
• membrane bound disaccharidase = an enzyme which isn’t released into the lumen of the ileum but is part of the cell-surface membranes of the epithelial cells that line the ileum
• sucrase = produced by the epithelial lining and is a membrane bound disaccharidase which breaks down sucrose into the monosaccharides glucose and fructose
• maximising absorption in the small intestine:

  • internal walls are folded into villi
  • villi have thin walls
  • villi have lots of capillaries
  • villi contain muscles to mix contents of the ileum
• epithelial cells that line the ileum:

  • microvilli to increase surface area for diffusion
  • many mitochondria for active transport
  • carrier proteins for active transport
  • channel proteins for facilitated diffusion