Quarter 4 Science

• Digestion


  The chief function of the digestive system. It breaks down food mechanically and chemically.
• The journey of the food starts from the mouth down to

  Gall bladder

  the anus takes about 18-20 hours.
• INGESTION - is the first process that happens in digestive system. It is the journey of taking in food or any substance into the body through the mouth.
• Digestion -

  is the second process involved in digestive system. It is the process that involves break down of large food molecules into smaller molecules for easy absorption of the cells. 
• Both chemical and mechanical digestions begin immediately in the Mouth
• Teeth

  cut, crush, and break it apart into tiny pieces 
• Mastication or chewing


  1. Tongue mixes food with saliva secreted by salivary glands

  2. Forms into a moist ball called bolus

  3. So it can be easily swallowed
• Mastication or chewing


  Mechanical digestion, the initial stage of digestion
• Saliva


  Contains salivary amylase, the enzyme that breaks down starch into smaller carbohydrate
• Swallowing


  1. Bolus passes from mouth to esophagus

  2. Esophagus is a tube that attaches the mouth to the stomach
• Peristalsis


  1. Wave-like muscle contractions

  2. Push and transport foods and liquids in small sections to the stomach
• Stomach -

  is a J-shaped, bag-like muscular organ that can hold approximately one liter of fluid and food.
• Stomach


  Primary function is to store food
• Chyme


  Semifluid material formed from bolus that is acted upon by the gastric juices secreted by the stomach
• Stomach function


  1. Food turns to chyme

  2. Acted on by stomach acid
• Stomach walls


  • Have special cells that secrete gastric juices like hydrochloric acid and pepsin
  • Begin the chemical breakdown of proteins
• Enzymes in The mouth

  • Salivary Amylase
• Enzyme is the Stomach

  • Hydrochloric Acid
  • Pepsin
• Enzyme in Duodenum

  • Pancreatic Amylase
  • Pancreatic Lipase
• Enzyme in Small Intestine

  • Lactase
  • Maltase
  • Socrase-Isomaltase
  • Peptidase
• The liver -

  produces bile, a green fluid that turns large fat droplets into smaller ones and stores them in the gall bladder.
• bile gets into the small intestine and helps in the digestion of fat.