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• Digestive system


  Consists of a number of organs that break down food in order to absorb nutrients needed by the body
• Two main groups of the digestive system

  • Alimentary canal (gastrointestinal tract)
  • Accessory organs
• Alimentary canal


  • A long, winding, and continuous tube that extends from the mouth to the anus
  • Includes mouth, esophagus, stomach, small intestine, large intestine
• Accessory organs


  • Located within or outside the alimentary canal and communicate with it by way of ducts
  • Includes teeth, salivary glands, pancreas, liver, gallbladder
• Digestive processes


  • Ingestion
  • Propulsion
  • Mechanical digestion
  • Chemical digestion
  • Absorption
  • Defecation
• Ingestion


  Process of bringing food into the digestive system, where the point of entry is the mouth
• Propulsion


  Movement of food through the alimentary canal
• Swallowing


  Series of muscular events that push the food through the alimentary canal by the of alternating waves of muscle contraction and relaxation
• Mechanical digestion


  Breakdown of food particles by chewing, grinding, and mixing
• Chemical digestion


  Breaking down of food into simpler molecules that can be absorbed by the body
• Absorption


  Transport of digested food materials from the cavity of the alimentary canal to the blood
• Defecation


  Elimination of indigestible matter from the body in the form of feces
• Mouth


  The first organ of the digestive system
• Saliva


  Moistens the food we eat
• Oral cavity


  Space between the tongue and palate within the mouth
• Tongue


  A muscular organ covered with taste buds
• Bolus


  The shape of food that the tongue manipulates
• Pharynx


  A chamber located behind the oral cavity extending from the internal nares to the larynx
• Pepsinogen


  A zymogenic (enzyme-producing) cell in an inactive form
• Pepsin


  A powerful protein-splitting enzyme
• Pancreas


  An accessory organ of the digestive system, closely associated with the small intestine and provides a variety of digestive enzymes
• Pancreatic juice


  An alkaline fluid containing enzymes capable of digesting carbohydrates, proteins, fats, and nucleic acids
• Pancreatic amylase


  A pancreatic enzyme that digests carbohydrates
• Pancreatic lipase


  An enzyme that aids in the digestion of fats
• Liver


  The largest visceral organ of the body
• Lipoprotein


  Small proteins
• Bile


  A fluid produced by liver cells that aids in digestion and removes toxic substances from the body
• Gallbladder


  An accessory organ located under the liver, used to store and concentrate bile secreted by the liver
• Sphincter of Oddi


  A muscle that is normally in a contracted state, causing bile to collect in the duct and gallbladder
• Small intestine


  The body's most important digestive organ, completes the process of mechanical and chemical digestion
• Segments of the small intestine


  • Duodenum
  • Jejunum
  • Ileum
• Large intestine


  The final segment of the alimentary canal, absorbs water and undigested food into the form of feces
• Segments of the large intestine


  • Cecum
  • Colon (ascending, transverse, descending, sigmoid)
  • Rectum
  • Anal canal
• Rectum


  Located against the sacrum in the pelvic cavity, extends downward until it reaches the last segment, the anal canal
• Anal canal


  Opens to the exterior of the anus
• Internal sphincter


  Composed of smooth muscle, involuntary
• External sphincter


  Composed of skeletal muscle, voluntary
• Villi


  Threadlike projections that increase the surface area for nutrient absorption
• Digestive juices


  • Saliva
  • Gastric
  • Pancreatic
  • Intestinal
• Saliva


  Works on starch, converting it to maltose