Note Taking Guide Topic # 3024 Comparative Digestive Systems Digestive Systems Overview 1. Digestion Digestion: Food enters the mouth and goes through mechanical and chemical changes as it passes through the alimentary canal. 2. Types of Stomachs Man, Pig Cattle, Sheep Goats Horses, Rabbits, Guinea Pigs 3. Parts of Digestive Tract Mouth: Salivary Glands Mastication secrete juices that contain enzymes to help break up the food chewing, crushing, preparing food for swallowing : funnel shaped muscle between mouth and esophagus part of digestive and respiratory tracts
: muscular tube connecting pharynx to stomach muscle contractions move food down to stomach : located between esophagus and small intestine Two basic types A. Simple Stomach Divided into three regions C F P Digestion: is mechanical, muscle contractions is chemical, enzymes soften and break down macromolecules of food enzymes are catalysts, they start the chemical reactions Enzymes that break down food: Gastric-break down protein in stomach Live and pancreatic-break down fats in small intestine Intestinal-break down carbohydrates and proteins in small intestine B. Ruminant Stomach Occupies of the abdominal cavity
composes of ruminant stomach in mature bovine animals and 30% in young animals composes about of bovine stomach prevents indigestible objects from entering the stomach Composes of bovine stomach absorbs mostly water the "true" stomach composes of stomach in mature animals and in young animals Digestion in the Ruminant Stomach Rumination: The process of regurgitation, re-mastication, re-salivation and reswallowing of food. Purpose: to smash and break up food which provides more surface area for bacteria to break down : long, coiled tube connecting the stomach with the large intestine. Is covered by villi which increase surface area to increase absorption Food moves through by muscle contractions called peristaltic movement Final breakdown and absorption of nutrients occurs here. Includes cecum, colon and rectum Absorbs water Very little nutrient absorption takes place here Accessory Organs Pancreas
secretes enzymes which breakdown fat and starches secrets bile which digests fats 4. The Digestion Process Food is broken down Animals have digestive systems adapted to the foods that they consume Four types of digestive systems 5. Ruminant Digestive System Modified to handle the breakdown of large amounts of fiber _- no upper incisors, hard palate molars for grinding coarse vegetation saliva does not contain enzymes muscular tube connecting the mouth to the stomach The Four Compartmented Stomach : storage area and fermentation vat : nails and wire may be found here - - hardware stomach : eliminates excess water from feed
: true stomach, gastric juices and enzymes are secreted 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 rechewed Small Intestine food nutrients absorbed into blood contains bile and pancreatic juices Large Intestine Contains Cecum, Colon and Rectum Cecum: sac at junction of small 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 6. Monogastric Digestive System Characterized by inability to digest roughage efficiently has upper and lower incisors digestive enzyme secreted which breaks down nutrients
Esophagus Stomach Secretes to break down nutrients enzymes such as pepsin also secreted here action mixes food Small and large intestines function just as in ruminant systems 7. Avian Digestive Systems Characterized by several organs not found in other species that are adapted for grinding hard or encased food Mouth no teeth which leads to the saying "scarce as a hen's teeth"!! Esophagus connects mouth and stomach Stomach Contains Two Parts Proventriculus: same as monogastric stomach and provides digestive excretions Gizzard: located after proventriculus, very muscular, used to grind food Small Intestine similar functions as in ruminants and monogastric systems Large Intestine
similar functions as in ruminants and monogastrics systems " ": chamber into which urinary and genital canals open " ": aids in fiber digestion and absorption 8. Equine Digestive Systems Characterized by non-ruminant animals that consume and digest feeds high in fiber Mouth molars adapted to chewing fibrous feeds no digestive enzymes in saliva not well adapted for regurgitation connects mouth and stomach Stomach Small Intestine similar to monogastric and ruminant systems no gall bladder to store bile enlarged cecum to aid in fiber breakdown Large Intestine similar to monogastric systems cecum (at junction of small and large intestines) and colon take up most of the volume of the equine digestive system 9. Accessory Organs
Organs that aid in the digestive process without actually being part of the digestive system Pancreas Liver produces and secretes digestive enzymes produces insulin which regulates carbohydrate metabolism _ breaks down fatty acids stores iron, handles fats and carbohydrates in the blood