Digestive System

• Ingestion


  Intake of food which happens in the mouth
• Digestion


  Breaking down of food so that it can be absorbed by the body
• Mechanical Digestion


  1. Large pieces of food are broken into smaller particles that can be acted upon by various enzymes

  2. Begins in the mouth with chewing or mastication

  3. Continues with churning and mixing actions in the stomach
• Chemical Digestion


  1. Complex molecules of carbohydrates, proteins, and fats are transformed into smaller molecules that can be absorbed and utilized by the cells

  2. Uses water and digestive enzymes to break down the complex molecules

  3. Happens in stomach and small intestine
• Absorption


  • The process of absorbing food in the form of nutrients into the blood stream of the body
  • Occurs in the small intestine
  • Water absorption happens in the large intestine
• Assimilation


  • The process of nutrients being absorbed by each cell of the body in the form of energy
  • Happens in the small intestine
• Egestion


  • Secretion of waste, unwanted and excess substances from the body after food has been digested
  • Takes place in the anus
• Parts of the digestive system

  • Mouth
  • Salivary Glands
  • Pharynx
  • Esophagus
  • Liver
  • Stomach
  • Gall bladder
  • Pancreas
  • Small Intestine
  • Appendix
  • Large Intestine
  • Rectum
  • Anus
• Mouth


  Where food enters the alimentary canal and digestion begins
• Salivary Glands


  Produce saliva containing amylase
• Pharynx


  Known as throat that gets food from the mouth to esophagus
• Esophagus


  Carries food to stomach by peristalsis (wave-like contractions)
• Liver


  Produces bile and holds bile
• Stomach


  Partially digests the food (chyme)
• Gall bladder


  Stores bile
• Pancreas


  Produces 3 digestive enzymes
• Small Intestine


  Produces digestive enzymes and absorbs food which has been digested
• Appendix


  No known function
• Large Intestine


  Stores undigested food and reabsorbs water
• Rectum


  Holds undigested food until elimination
• Anus


  Opening through which undigested food is eliminated
• Chemical digestion could not take place without the help of digestive enzymes
• Enzyme


  A protein that speeds up chemical reactions in the body
• Digestive enzymes


  • Speed up chemical reactions that break down large food molecules into small molecules
  • Are released, or secreted, by the organs of the digestive system
  • Include proteases that digest proteins, and nucleases that digest nucleic acids
• Digestive enzymes

  • Amylase (produced in the mouth, breaks down starch)
  • Pepsin (produced in the stomach, breaks down proteins)
  • Trypsin (produced in the pancreas, breaks down proteins)
  • Pancreatic lipase (produced in the pancreas, breaks down fats)
  • Deoxyribonuclease and ribonuclease (produced in the pancreas, break down nucleic acids)
• Bile salts

  • Bile acids that help to break down fat
  • Made in the liver
  • Secreted into the intestine to break down fats
• Digestion is important because your body needs nutrients from food and drink to work properly and stay healthy
• Process of Nutrition in the Digestive System

  1. Ingestion: Intake of food in the mouth

  2. Digestion: Breaking down of food

  3. Absorption: Absorbing food in the form of nutrients into the bloodstream in the small intestine

  4. Assimilation: Nutrients being absorbed by each cell of the body in the small intestine

  5. Egestion: Secretion of waste, unwanted and excess substances from the body in the anus
• Amylase - helps break down large starch molecules into smaller sugar molecules in the mouth
• Pepsin - helps break down proteins into amino acids
• Trypsin (produced in the pancreas) helps break down proteins
• Trachea - known as the windpipe
• Mastication - other word for chewing
• The bolus then moves through the stomach mixing gastric acid secretion to form chyme.
• Hydrochloric Acid - is a naturally occuring acid in the stomach