Comparative Digestion Systems &Process Modified by Ashlee Gibson
Dec 22, 2015
Comparative Digestion Systems &Process
Modified by Ashlee Gibson
The Digestion Process
• Food is broken down• Animals have digestive systems adapted to
the foods that they consume• Four types of digestive systems
– Ruminant(polygstric)– Simple Stomach(monogastric)– Avian– Equine-modified simple stomach
Ruminant Digestive System
Modified to handle the breakdown of large amounts of fiber
Ruminant Digestive System
• Mouth– no upper incisors, hard palate– molars for grinding coarse vegetation– saliva does not contain enzymes
• Esophagus – muscular tube connecting the mouth to the
stomach
Ruminant Digestive Systems
The Four Compartmented Stomach
• Rumen: storage area and fermentation vat
• Reticulum: nails and wire may be found here-hardware stomach
• Omasum: eliminates excess water from feed
• Abomasum: true stomach, gastric juices and enzymes are secreted
Ruminant Digestive Systems
Stomach (cont.)
• Regurgitation: first step in rumination– large quantities of roughage are consumed and
are chewed just enough to swallow– after swallowing, regurgitation (“cud chewing”)
takes place, food is re-chewed
Ruminant Digestive System
• Small Intestine– connects stomach to large intestine– food nutrients absorbed into blood– contains bile and pancreatic juices– pushes food through by muscle contractions
Ruminant Digestive System
• Large Intestine– Contains Cecum, Colon and Rectum
• Cecum: sac at junction of small intestine and large intestine
• Colon and rectum: at end of system
– not as long as small intestine, but larger in diameter
– water and some nutrient absorption occurs here– where residue solidifies before excretion
Monogastric Digestive System
Characterized by inability to digest roughage efficiently
Monogastric Digestive System
• Mouth– has upper and lower incisors– digestive enzymes secreted which breaks down
nutrients
• Esophagus– connects mouth to stomach
Monogastric Digestive System
• Stomach – secretes Hydrochloric Acid to break down
nutrients– enzymes such as pepsin also secreted here– churning action mixes food– small and large intestine
• function just as in ruminant systems
Avian Digestive Systems
Characterized by several organs not found in other species that are
adapted for grinding hard or encased food
Avian Digestive Systems
• Mouth – no teeth which leads to the saying “scarce as a
hen’s teeth!!”– Salivation excretion moistens food
• Esophagus – has a modification called the “crop” which
stores and moistens food– connects mouth and stomach
Avian Digestive Systems
• Stomach– Contains two parts
• Proventriculus:same as monogastric stomach and provides digestive excretions
• Gizzard: located after proventriculus, very muscular, used to grind food
Avian Digestive Systems
• Small Intestine– similar functions as in ruminants and monogastric
systems
• Large Intestine– similar functions as in ruminants and monogastric
systems– “cloaca”: chamber into which urinary and genital
canals open– “ceca”: aids in fiber digestion and absorption
Equine Digestive Systems
Characterized by non-ruminant animals that consume and digest
feeds high in fiber
Equine Digestive Systems
• Mouth – intact top and bottom incisors– molars adapted to chewing fibrous feeds– no digestive enzymes in saliva
• Esophagus– not well adapted for regurgitation– connects mouth and stomach
Equine Digestive System
• Stomach– similar to monogastric system
• Small intestine– similar to monogastric and ruminant systems– no gall bladder to store bile – enlarged cecum to aid in fiber breakdown
Equine Digestive System
• Large Intestine – similar to monogastric systems– cecum (at junction of small and lare intestines)
and colon take up most of the volume of the equine digestive system
Accessory Organs
Organs that aid in the digestive process without actually being part of
the digestive system
Accessory Organs
• Pancreas – produces and secretes digestive enzymes– produces insulin which regulates carbohydrate
metabolism
• Liver– produces bile-breaks down fatty acids– stores iron, handles fats and carbohydrates in
the blood
The End!!
References
• Human Biology– http://ultranet.com/~jkimball/Biologypages/G/GITract.html