Digestive system 2

• Digestive system


  System that breaks down large, nutrient macromolecules into simpler molecules for use by an organism
• Digestion

  Breaking down large, nutrient macromolecules into simpler molecules for use by an organism
• Types of stomachs

  • Simple stomach
  • Complex stomach
  • Simple stomach with enlarged cecum
• Simple stomach

  • Man, Pig
• Complex stomach

  • Cattle, Sheep, Goats
• Simple stomach with enlarged cecum

  • Horses, Rabbits, Guinea Pigs
• Parts of digestive tract

  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine

  
• Mouth

  Initial opening of alimentary canal
• Salivary glands

  • Secrete juices that contain enzymes to help break up the food
• Mastication

  Chewing, crushing, preparing food for swallowing
• Pharynx

  Funnel shaped muscle between mouth and esophagus, part of digestive and respiratory tracts
• Esophagus

  Muscular tube connecting pharynx to stomach, muscle contractions move food down to stomach
• Regions of simple stomach

  • Cardiac
  • Fundus
  • Pylorus
• Digestion in simple stomach

  Mechanical (muscle contractions), Chemical (enzymes soften and break down macromolecules)

  
• Enzymes that break down food

  • Gastric (break down proteins in stomach)
  • Liver and pancreatic (break down fats in small intestine)
  • Intestinal (break down carbohydrates and proteins in small intestine)
• Components of ruminant stomach

  • Rumen
  • Reticulum
  • Omasum
  • Abomasum

  
• Rumen

  Composes 80% of ruminant stomach in mature bovine animals and 30% in young animals

  
• Reticulum

  Composes about 5% of bovine stomach, prevents indigestible objects from entering the stomach
• Omasum

  Composes 7-8% of bovine stomach, absorbs mostly water

  
• Abomasum

  The "true" stomach, composes 7-8% of stomach in mature animals and 70% in young animals

  
• Rumination

  The process of regurgitation, re-mastication, re-salivation and re-swallowing of food, to smash and break up food which provides more surface area for bacteria to break down
• Small intestine

  Long, coiled tube connecting the stomach with the large intestine, covered by villi which increases surface area to increase absorption, food moves through by muscle contractions called peristaltic movement, final breakdown and absorption of nutrients occurs here

  
• Large intestine

  Includes cecum, colon and rectum, absorbs water, very little nutrient absorption takes place here
• Accessory organs

  • Pancreas
  • Liver
• Pancreas

  Secretes enzymes which breakdown fat and starches
• Liver

  Secretes bile which digest fats
• Types of digestive systems

  • Ruminant (polygastric)
  • Simple stomach (monogastric)
  • Avian
  • Equine (modified simple stomach)

  
• Ruminant digestive system

  • Modified to handle the breakdown of large amounts of fiber
• Monogastric digestive system

  • Characterized by inability to digest roughage efficiently
• Avian digestive system

  • Characterized by several organs not found in other species that are adapted for grinding hard or encased food

  
• Equine digestive system

  • Characterized by non-ruminant animals that consume and digest feeds high in fiber