Science 8 ( DIGESTIVE SYSTEM 1)

• Mouth


  • Teeth mechanically breakdown food into small pieces
  • Tongue mixes food with saliva (contains amylase, which helps break down starch)
• Pharynx


  Hollow tube inside the neck, about 8 inches long, also known as the throat
• Epiglottis


  Flap-like structure at the back of the throat that closes over the trachea, preventing food from entering
• Esophagus


  • Approximately 20 cm long
  • Moves food from the throat to the stomach using muscle movement called peristalsis
• Stomach


  • J-shaped muscular bag that stores the food you eat, breaks it down into tiny pieces
  • Secretes mucus
  • Mixes food with digestive juices that contain enzymes to break down proteins and lipids
  • Contains acid (HCl)
• Chyme

  Food found in the stomach
• Small Intestine


  • Roughly 7 meters long
  • Lining of intestine walls has finger-like projections called villi to increase surface area
  • Villi are covered in microvilli which further increases surface area for absorption
• Large Intestine


  • About 15 meters long
  • Accepts what the small intestine doesn't absorb
• Rectum


  Short-term storage which holds feces before it is expelled
• Ingestion


  The consumption of a substance by an organism
• Absorption


  Nutrients from food (including carbohydrates, proteins, fats, vitamins, and minerals) pass through channels in the intestinal wall and into the bloodstream
• Assimilation

  The movement of digested food molecules into cells in the body where they are used, e.g. glucose is transferred into cells for respiration and energy provision
• Peristalsis - moves food from the throat to the stomach using muscle movement