Nutrition in Humans

• Food is taken into the body

  Ingestion
• Breaking down food molecules into smaller soluble substances


  Digestion
• Absorption of digested food substances


  Small Intestine
• Removal of Undigested Matter

  Egestion
• Convertion of absorbed food substances to new protoplasm or energy


  Assimilation in the Liver
• Physical digestion is ___

  mechanical break-up of food into smaller particles
• Examples of Physical Digestion

  Chewing Peristalsis Emulsification
• Chemical Digestion is ___

  break-down of large molecules to smaller molecules for absorption
• Function of Physical Digestion

  Increase SA:VR
• Bile is produced in the liver and stored in the gall bladder
• Function of Bile

  Breaks up fats from big to small droplets for easier digestion by lipase enzymes
• Teeth


  Grinding Action breaks up large pieces of food into smaller pieces to Increase SA:VR
• Salivary Glands


  secrete saliva containing Salivary Amylase which digests Starch into Maltose through salivary ducts
• Tongue

  mixes the food with saliva

  rolls the food into a bolus
• Muscle on the outside

  Longitudinal
• Muscle on the inside

  Circular
• Peristalsis is a churning action
• Gastric Juice contains

  Hydrochloric Acid and Protease
• Proteins are partially digested into polypeptides in Stomach by Protease
• Gastric Acid activates Protease due to its acidic pH level, Protease would otherwise be inactive
• Small Intestine consists of ___

  Duodenum Jejunum Ileum
• Duodenum

  Main site of digestion

  Many enzymes present

  Connected to Liver & Pancreas
• Small Intestine has a pH of 9
• Ileum

  Most Absorption of digested food substances
• Pancreas secretes Pancreatic Juice


  which contains Protease Pancreatic Amylase and Lipase
• Intestinal Juice contains

  Lipase Protease Maltase
• Digestion in the mouth


  • Saliva
  • Salivary glands
  • Salivary amylase
  • Starch → maltose
• Digestion in the stomach

  • Gastric juice
  • Gastric glands
  • Protease
  • Protein → Polypeptides
• Digestion in the small intestine

  • Bile
  • Liver
  • Bile not an enzyme
  • Bile emulsifies fats
  • Pancreatic juice
  • Pancreas
  • Protease
  • Pancreatic amylase
  • Protein → Polypeptides
  • Starch → maltose
  • Lipase
  • Fats → Fatty acids + Glycerol
  • Intestinal enzymes
  • Epithelial cells
  • Lipase
  • Fats → Fatty acids + Glycerol
  • Protease
  • Polypeptides → Amino acids
  • Maltase
  • Maltose → Glucose
• Presence of multiple folds in the wall, villi and microvilli 


  Increase SA:VR for higher rate of absorption of digested food substances
• One cell thick epithelium 


  shortens diffusion distance and makes it faster for nutrients to diffuse through the bloodstream
• Small Intestine has many blood capillaries to help carry away 


  absorbed nutrients quickly to

  maintain a steep concentration gradient
• Lacteal in the Villus

  Carry away absorbed fats quickly
• Epithelial Cells contain many mitochondria 


  provide energy for active transport of nutrients into the villi
• The Colon absorbs water and mineral salts