Digestive System

• The digestive system is composed of different organs that work together to break down food and nourish the body

  
• Digestion


  Breakdown of organic compounds into their simple forms for use by the cells
• Digestion


  The chemical breakdown of food into simpler substances that can be absorbed and used by the body

  
• Digestion involves important processes in order to carry out the function of the digestive system

  
• Ingestion


  Taking in food or any substance into the body through the mouth
• Digestion


  1. Breaking down of large food molecules into smaller molecules for easy absorption by the cells

  2. Includes both chemical and mechanical digestion

  
• Mouth


  • Teeth cut, crush, and break food into tiny pieces
  • Tongue helps mix food with saliva to form a moist ball called bolus
• Saliva


  Contains salivary amylase that breaks down starch into smaller carbohydrates
• Peristalsis


  Wave-like muscle contractions that push and transport food and liquids from the mouth to the stomach
• Stomach


  1. shaped, bag-like muscular organ that stores food and turns it into chyme (semifluid material)
• Gastric juices


  Hydrochloric acid and pepsin that begin the chemical breakdown of proteins
• Organs that secrete essential substances

  • Liver
  • Pancreas
  • Gall bladder
• Bile


  Green fluid produced by the liver that turns large fat droplets into smaller ones and aids in fat digestion
• Pancreatic enzymes


  Amylase, peptidase, and lipase that aid in the digestion of carbohydrates, proteins, and fats respectively

  
• Small intestine


  Organ that breaks down food further into substances like glucose that can be absorbed by the villi

  
• Duodenum


  First and shortest part of the small intestine that resumes chemical digestion and prepares for absorption

  
• Absorption


  Passing of soluble food molecules through the wall of the small intestine into the blood capillaries of the villi

  
• Assimilation

  Movement of digested food nutrients into the blood vessels of the small intestine and use of nutrients by the body cells

  
• Ileum


  Third part of the small intestine that assimilates (absorbs) B12 and reabsorbs conjugated bile salts
• Large intestine


  Where reabsorption of liquid, electrolytes and some vitamins from undigested food takes place

  
• Egestion


  Release of undigested food (feces) from the rectum through the anus by defecation