Digestive System

• Functions of the Digestive System

  • Take in food
  • Mechanically breakdown food
  • Chemically breakdown food into small molecules called nutrients
  • Rid body of waste
• Digestive tract


  Long tube beginning where food first "touches" the inside of our body
• Digestion


  Begins in the mouth
• Teeth


  • Incisors cut food
  • Molars grind food into smaller pieces, increasing the surface area
• Mechanical digestion


  Breaking down food physically
• Salivary glands


  • Secrete saliva
• Saliva


  Contains water and salivary amylases (enzyme that chemically digests starch)
• Tongue


  • Skeletal muscle that mixes the chewed food with saliva
• Bolus


  The chewed food mixed with saliva
• Taste buds


  • First line of defense against getting sick by identifying spoiled food
• Chyme


  The semi-fluid mass of partly digested food that passes from the stomach into the small intestine
• Chyme exits the stomach


  through the pyloric sphincter and small intestine into the duodenum
• Small intestine


  • A long tube approximately 6 m long
  • Where digestion is finished
  • Where nutrients are absorbed
• Chyme movement in small intestine

  1. Via peristalsis

  2. Small intestine is made up of smooth muscle
• Bile


  • Made in the liver
  • Stored in the gallbladder
  • Released into the duodenum through the bile duct
  • Emulsifies fat (mechanical digestion)
• Pancreatic juice


  Contains sodium bicarbonate which neutralizes the acidic chyme from the stomach (pH 8.0)
• Pancreatic enzymes


  1. Pancreatic amylase digests starch

  2. Trypsin digests polypeptides (activated from trypsinogen)

  3. Lipase digests fats
• Enzymes break chemical bonds by adding water molecules (hydrolysis)
• Salivary and pancreatic amylase digest starch by breaking bonds through hydrolysis
• Name of the small intestine part?

  Duodenum