VTS 150 Animal Nutrition Fall 2010 Instructor:  Beth Alden, DVM
Course Objectives <ul><li>Understanding of different digestive systems </li></ul><ul><li>Learn the nutritional needs of sm...
Resources for Class <ul><li>Textbook : </li></ul><ul><li>Nutrition for Veterinary  Technicians and Nurses ,  Ann Wortinger...
Resources on Library Reserve Small Animal Clinical Nutrition 4 th  Edition,   Hand,Thatcher,  Remillard, Roudebush,   The ...
What’s Required of You: <ul><li>2 Unit Exams </li></ul><ul><li>Three (3) Student Projects </li></ul><ul><li>Final Exam </l...
<ul><li>Digestive System Classifications </li></ul>
Digestive Classifications Two Methods of  Digestive System Classification Food Source Stomach Type
<ul><li>Herbivores:  Plant eaters </li></ul><ul><li>Carnivores: Meat Eaters </li></ul><ul><li>Omnivores: Plant and Meat Ea...
Herbivores <ul><li>Plant material makes up diet </li></ul><ul><ul><li>Rough vegetation, nitrogen source, minerals & water ...
Carnivores <ul><li>Animal material (flesh, muscle, etc.) makes up diet </li></ul><ul><li>Food more easily digested than in...
Types of Digestive Systems Four compartment stomach: Reticulum, Rumen, Omasum & Abomasum (cows, sheep, goats) One “true” s...
<ul><li>Monogastric Animals </li></ul>
The Monogastric Stomach <ul><li>Five sections: </li></ul><ul><ul><li>Cardia </li></ul></ul><ul><ul><li>Fundus </li></ul></...
The Monogastric Stomach <ul><li>1. Cardia </li></ul><ul><li>Area immediately  surrounding the opening from the esophagus i...
The Monogastric Stomach <ul><li>2. Fundus </li></ul><ul><ul><li>Located below the cardia </li></ul></ul><ul><ul><li>Blind ...
The Monogastric Stomach <ul><li>3. Body </li></ul><ul><li>Distends to receive food </li></ul><ul><li>Rich with gastric gla...
The Monogastric Stomach <ul><li>4. Antrum </li></ul><ul><li>Grinds up food and regulates HCl </li></ul><ul><li>Also contai...
The Monogastric Stomach <ul><li>5. Pylorus </li></ul><ul><li>Muscular ring (sphincter)  </li></ul><ul><li>Regulates moveme...
<ul><li>Ruminant Animals </li></ul>
The Ruminant Animal <ul><li>Chews and swallows its food then regurgitates “cud” to chew on it more before swallowing again...
The Ruminant Stomach <ul><li>Four Compartments: </li></ul><ul><ul><li>Reticulum </li></ul></ul><ul><ul><li>Rumen </li></ul...
The Ruminant Stomach <ul><li>1. The Reticulum </li></ul><ul><li>Smallest, most cranial compartment </li></ul><ul><li>Separ...
The Ruminant Stomach <ul><li>1. The Reticulum </li></ul><ul><li>Honeycombed inside to increase absorptive surface </li></u...
The Ruminant Stomach <ul><li>2. The Rumen </li></ul><ul><li>Large fermentative vat (40 - 50 gallon capacity) </li></ul><ul...
The Ruminant Stomach © University of Bristol, 1988 Pillar Papillae Papillae
The Ruminant Stomach <ul><li>2. The Rumen </li></ul><ul><li>During contractions, pillars close off certain sacs of the rum...
The Ruminant Stomach <ul><li>What reticuloruminal contractions do : </li></ul><ul><ul><li>Allow “cud” to be regurgitated u...
The Ruminant Stomach <ul><li>Fermentative digestion begins in the rumen </li></ul><ul><li>Bacterial and protozoal enzymes ...
The Ruminant Stomach <ul><li>Carbohydrate Metabolism,  continued </li></ul><ul><li>Volatile fatty acids are by-products of...
The Ruminant Stomach <ul><li>Protein Metabolism: </li></ul><ul><li>Rumen microbial enzymes attack proteins  (just like car...
The Ruminant Stomach <ul><li>Protein Metabolism,  continued </li></ul><ul><li>Liver secretes  urea*  into the rumen, which...
The Ruminant Stomach <ul><li>Other Notes about the Rumen </li></ul><ul><li>Provides B vitamins; Vitamin K </li></ul><ul><l...
The  Ruminant Stomach <ul><li>3.  Omasum </li></ul><ul><li>Muscular organ located off the reticulum </li></ul><ul><li>Inge...
The Ruminant Stomach <ul><li>3. Omasum </li></ul><ul><ul><li>Primary functions </li></ul></ul><ul><ul><li>Break down food ...
The Ruminant Stomach <ul><li>4. Abomasum </li></ul><ul><li>“ True stomach” of ruminant </li></ul><ul><li>Functions similar...
Young Ruminant Digestive Tract <ul><li>Functions as a monogastric system </li></ul><ul><li>No fermentative digestion  (rum...
Young Ruminant Digestive Tract <ul><li>Abomasum is largest of 4 stomachs for the  first few weeks </li></ul><ul><li>Rumen ...
Chronology of Digestive System <ul><li>GI tract extends from mouth to the anus and performs different functions at differe...
Chronology of Digestion 1.  Prehension <ul><li>Grasping food with teeth or lips </li></ul>
Chronology of Digestion : 2. Mechanical Grinding Down of Food Carnivore Teeth Pointed to facilitate holding and tearing of...
Chronology of Digestion: 2. Mechanical Grinding Down of Food Herbivore Teeth Flat, occlusal surface for grinding
Chronology of Digestion: 2. Mechanical Grinding Down of Food <ul><li>Incisors  – Teeth in the front for holding and tearin...
Chronology of Digestion: 2. Mechanical Grinding Down of Food Ruminant Teeth No upper incisors or upper canine teeth Dental...
Chronology of Digestion: 2. Mechanical Grinding Down of Food Positional Location of Teeth - Terminology Maxilla Upper Arca...
Chronology of Digestion: 3.  Chemical Digestion of Food <ul><li>Saliva mixes with food during chewing  </li></ul><ul><li>T...
Chronology of Digestion 3.  Chemical Digestion of Food <ul><li>Digestive enzymes and buffers in saliva </li></ul><ul><li>A...
Chronology of Digestion 3.  Chemical Digestion of Food <ul><li>Epiglottis   </li></ul><ul><ul><ul><li>Cartilage projection...
Chronology of Digestion 3.  Chemical Digestion of Food <ul><li>Stomach   </li></ul><ul><ul><ul><li>Stores food  </li></ul>...
Chronology of Digestion 3.  Chemical Digestion of Food <ul><li>Liver </li></ul><ul><ul><ul><li>Secretes bile acids to help...
Chronology of Digestion 4.  Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>Duodenum, Jejunu...
Chronology of Digestion 4.  Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>No clear demarca...
Chronology of Digestion 4.  Absorption of Nutrients & Water <ul><li>Villi </li></ul><ul><ul><li>Millions of cylindrical, f...
Chronology of Digestion 4.  Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>Absorbs electrol...
Chronology of Digestion 4.  Absorption of Nutrients & Water <ul><li>Nutrient digestion in the small intestine </li></ul><u...
Chronology of Digestion 5.  Elimination of Waste Material <ul><li>Large Intestine:  Cecum & Colon </li></ul><ul><ul><li>Re...
Chronology of Digestion 5.  Elimination of Waste Material *Horses are different Colon Cecum    “blind sac” Carnivores Simp...
Chronology of Digestion 5. Elimination of Waste Material <ul><li>Colon & Cecum comprise the  “Hindgut” </li></ul><ul><li>4...
Chronology of Digestion 5. Elimination of Waste Material <ul><li>Rectum </li></ul><ul><ul><li>Terminal portion of colon </...
Next Week… <ul><li>Session 2:  </li></ul><ul><li>Basic Nutrients </li></ul>
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Digestive system classifications

  1. 1. VTS 150 Animal Nutrition Fall 2010 Instructor: Beth Alden, DVM
  2. 2. Course Objectives <ul><li>Understanding of different digestive systems </li></ul><ul><li>Learn the nutritional needs of small companion animals, “pocket pets,” large animals and exotic pets </li></ul><ul><li>Learn about nutritional diseases for several species </li></ul><ul><li>Learn how to calculate an animal’s energy needs </li></ul><ul><li>Know how to evaluate a pet food label and ingredients </li></ul><ul><li>Learn common toxicities for dogs and cats </li></ul>
  3. 3. Resources for Class <ul><li>Textbook : </li></ul><ul><li>Nutrition for Veterinary Technicians and Nurses , Ann Wortinger , </li></ul><ul><li>Blackwell Publishing, 2007 </li></ul>
  4. 4. Resources on Library Reserve Small Animal Clinical Nutrition 4 th Edition, Hand,Thatcher, Remillard, Roudebush, The Mark Morris Institute, 2000
  5. 5. What’s Required of You: <ul><li>2 Unit Exams </li></ul><ul><li>Three (3) Student Projects </li></ul><ul><li>Final Exam </li></ul>
  6. 6. <ul><li>Digestive System Classifications </li></ul>
  7. 7. Digestive Classifications Two Methods of Digestive System Classification Food Source Stomach Type
  8. 8. <ul><li>Herbivores: Plant eaters </li></ul><ul><li>Carnivores: Meat Eaters </li></ul><ul><li>Omnivores: Plant and Meat Eaters </li></ul>
  9. 9. Herbivores <ul><li>Plant material makes up diet </li></ul><ul><ul><li>Rough vegetation, nitrogen source, minerals & water </li></ul></ul><ul><li>Difficult to digest </li></ul><ul><ul><li>Plant cell wall is hard to break down </li></ul></ul><ul><ul><li>Energy from the plant is tied up in cellulose that animal cannot digest on its own </li></ul></ul><ul><ul><li>The animal has developed a large complex gut to digest this material </li></ul></ul><ul><ul><li>Microbial action in gut is necessary to break down the cellulose and release its energy </li></ul></ul><ul><ul><li>Little of the food’s energy is absorbed by host </li></ul></ul>
  10. 10. Carnivores <ul><li>Animal material (flesh, muscle, etc.) makes up diet </li></ul><ul><li>Food more easily digested than in herbivores </li></ul><ul><li>The animal has a very simple “gut “ </li></ul><ul><li>Most of food’s energy is absorbed by host </li></ul><ul><li>Mechanical breakdown of food is less involved </li></ul>
  11. 11. Types of Digestive Systems Four compartment stomach: Reticulum, Rumen, Omasum & Abomasum (cows, sheep, goats) One “true” stomach (dogs, cats, pigs, horses) Ruminant Monogastric
  12. 12. <ul><li>Monogastric Animals </li></ul>
  13. 13. The Monogastric Stomach <ul><li>Five sections: </li></ul><ul><ul><li>Cardia </li></ul></ul><ul><ul><li>Fundus </li></ul></ul><ul><ul><li>Body </li></ul></ul><ul><ul><li>Antrum </li></ul></ul><ul><ul><li>Pylorus </li></ul></ul>Source: University of California at Davis
  14. 14. The Monogastric Stomach <ul><li>1. Cardia </li></ul><ul><li>Area immediately surrounding the opening from the esophagus into the stomach </li></ul><ul><li>Muscular tone prevents reflux of stomach contents into the esophagus </li></ul>CARDIA Source: University of California at Davis
  15. 15. The Monogastric Stomach <ul><li>2. Fundus </li></ul><ul><ul><li>Located below the cardia </li></ul></ul><ul><ul><li>Blind pouch that distends as food is swallowed </li></ul></ul>Source: University of California at Davis FUNDUS CARDIA
  16. 16. The Monogastric Stomach <ul><li>3. Body </li></ul><ul><li>Distends to receive food </li></ul><ul><li>Rich with gastric glands </li></ul>Parietal Cells : Hydrochloric acid (HCl) Chief Cells : Pepsinogen Mucous Cells : Mucus BODY Source: University of California at Davis FUNDUS CARDIA BODY
  17. 17. The Monogastric Stomach <ul><li>4. Antrum </li></ul><ul><li>Grinds up food and regulates HCl </li></ul><ul><li>Also contains glands </li></ul>G Cells: Gastrin Mucous Cells : Mucus BODY Source: University of California at Davis FUNDUS CARDIA BODY ANTRUM
  18. 18. The Monogastric Stomach <ul><li>5. Pylorus </li></ul><ul><li>Muscular ring (sphincter) </li></ul><ul><li>Regulates movement of chyme from stomach into duodenum </li></ul><ul><li>Helps prevent backflow of duodenal contents </li></ul>BODY Source: University of California at Davis FUNDUS CARDIA BODY ANTRUM PYLORUS DUODENUM
  19. 19. <ul><li>Ruminant Animals </li></ul>
  20. 20. The Ruminant Animal <ul><li>Chews and swallows its food then regurgitates “cud” to chew on it more before swallowing again </li></ul><ul><li>Has a “ prestomach ” configuration that is adapted to the herbivore diet </li></ul><ul><li>Four compartment stomach </li></ul>
  21. 21. The Ruminant Stomach <ul><li>Four Compartments: </li></ul><ul><ul><li>Reticulum </li></ul></ul><ul><ul><li>Rumen </li></ul></ul><ul><ul><li>Omasum </li></ul></ul><ul><ul><li>Abomasum </li></ul></ul>Source: University of California at Davis head tail
  22. 22. The Ruminant Stomach <ul><li>1. The Reticulum </li></ul><ul><li>Smallest, most cranial compartment </li></ul><ul><li>Separated from rumen by the ruminoreticular fold </li></ul><ul><li>Muscular wall is continuous with the rumen; contract in coordination </li></ul>RETICULUM Source: University of California at Davis head tail
  23. 23. The Ruminant Stomach <ul><li>1. The Reticulum </li></ul><ul><li>Honeycombed inside to increase absorptive surface </li></ul><ul><li>“ Hardware disease”- wires or nails swallowed by animal puncture wall of reticulum </li></ul>RETICULUM Inside of Reticulum Source: Colorado State University
  24. 24. The Ruminant Stomach <ul><li>2. The Rumen </li></ul><ul><li>Large fermentative vat (40 - 50 gallon capacity) </li></ul><ul><li>Processes plant material into usable energy </li></ul><ul><li>Lined with “Papillae” </li></ul><ul><li>Made up of series of muscular “ Pillars ” </li></ul>RUMEN Source: University of California at Davis head tail
  25. 25. The Ruminant Stomach © University of Bristol, 1988 Pillar Papillae Papillae
  26. 26. The Ruminant Stomach <ul><li>2. The Rumen </li></ul><ul><li>During contractions, pillars close off certain sacs of the rumen which allows mixing of ruminal contents </li></ul><ul><li>Mixing of contents essential for fermentative function of rumen </li></ul>RUMEN
  27. 27. The Ruminant Stomach <ul><li>What reticuloruminal contractions do : </li></ul><ul><ul><li>Allow “cud” to be regurgitated up the esophagus, where it’s re-chewed and re-swallowed </li></ul></ul><ul><ul><li>Allow “eructation” - built-up CO 2 or methane gas to be expelled from rumen. Gasses are forced into the reticulum and up the esophagus </li></ul></ul>RUMEN
  28. 28. The Ruminant Stomach <ul><li>Fermentative digestion begins in the rumen </li></ul><ul><li>Bacterial and protozoal enzymes break down foodstuffs </li></ul><ul><li>Carbohydrate Metabolism : </li></ul><ul><ul><li>Cellulase enzymes digest cellulose (plant cell layer) and transform complex carbohydrates into simple sugars </li></ul></ul><ul><ul><li>Simple sugars aren’t made available to host (like they are in monogastric animals), instead are absorbed into the microbes and converted to Volatile Fatty Acids (VFAs) </li></ul></ul>RUMEN
  29. 29. The Ruminant Stomach <ul><li>Carbohydrate Metabolism, continued </li></ul><ul><li>Volatile fatty acids are by-products of anaerobic fermentation by bacteria in rumen </li></ul><ul><li>Some VFAs absorbed into liver then converted to glucose, which is used by the animal’s cells </li></ul><ul><li>Other VFAs are used to produce adipose tissue and milk fat </li></ul>RUMEN
  30. 30. The Ruminant Stomach <ul><li>Protein Metabolism: </li></ul><ul><li>Rumen microbial enzymes attack proteins (just like carbohydrates) </li></ul><ul><li>Proteases reduce long proteins to amino acids and short peptides (short chains of amino acids) </li></ul><ul><li>Peptides are either incorporated into the protein structure of the microbes OR converted to ammonia (NH 3 + ) and VFAs </li></ul>RUMEN
  31. 31. The Ruminant Stomach <ul><li>Protein Metabolism, continued </li></ul><ul><li>Liver secretes urea* into the rumen, which provides additional nitrogen for the microbes </li></ul><ul><li>Microbes are then flushed from the reticulorumen to the omasum, abomasum and intestines; digested and serve as source of protein to the animal </li></ul>* Urea is sometimes added to poor-quality feed as a way of increasing nitrogen value RUMEN
  32. 32. The Ruminant Stomach <ul><li>Other Notes about the Rumen </li></ul><ul><li>Provides B vitamins; Vitamin K </li></ul><ul><li>Delicate balance: amount of food, growth of microbes and by-products </li></ul><ul><li>Changes in diet severely affect production of gas, VFAs and ammonia, causing fermentation process to completely stop </li></ul>RUMEN
  33. 33. The Ruminant Stomach <ul><li>3. Omasum </li></ul><ul><li>Muscular organ located off the reticulum </li></ul><ul><li>Ingesta moves into omasum from reticulorumen </li></ul><ul><li>Prevents large particles from leaving rumen and entering abomasum </li></ul>OMASUM Source: University of California at Davis head tail
  34. 34. The Ruminant Stomach <ul><li>3. Omasum </li></ul><ul><ul><li>Primary functions </li></ul></ul><ul><ul><li>Break down food particles further and move ingesta to abomasum </li></ul></ul><ul><ul><li>Absorb any excess VFAs </li></ul></ul><ul><ul><li>Remove bicarbonate ions from ingesta (to avoid altering acid pH of abomasum) </li></ul></ul>OMASUM
  35. 35. The Ruminant Stomach <ul><li>4. Abomasum </li></ul><ul><li>“ True stomach” of ruminant </li></ul><ul><li>Functions similar to monogastric stomach </li></ul>ABOMASUM Source: University of California at Davis head tail
  36. 36. Young Ruminant Digestive Tract <ul><li>Functions as a monogastric system </li></ul><ul><li>No fermentative digestion (rumen & reticulum are non-functional) </li></ul><ul><li>Reticular groove or Esophageal groove allows suckled milk to go to omasum </li></ul><ul><li>Suckling is important – helps groove to function </li></ul><ul><li>Bucket–fed calves spill milk into rumen & reticulum </li></ul>
  37. 37. Young Ruminant Digestive Tract <ul><li>Abomasum is largest of 4 stomachs for the first few weeks </li></ul><ul><li>Rumen & reticulum development rate dependent on diet: </li></ul><ul><ul><li>Grain & Hay fed – develop at 3 weeks </li></ul></ul><ul><ul><li>Milk fed – develop at 3 months </li></ul></ul>
  38. 38. Chronology of Digestive System <ul><li>GI tract extends from mouth to the anus and performs different functions at different parts </li></ul><ul><li>Chronology of Digestion : </li></ul><ul><ul><ul><li>Prehension </li></ul></ul></ul><ul><ul><ul><li>Mechanical grinding down of food </li></ul></ul></ul><ul><ul><ul><li>Chemical digestion of food </li></ul></ul></ul><ul><ul><ul><li>Absorption of nutrients and water </li></ul></ul></ul><ul><ul><ul><li>Elimination of waste material </li></ul></ul></ul>
  39. 39. Chronology of Digestion 1. Prehension <ul><li>Grasping food with teeth or lips </li></ul>
  40. 40. Chronology of Digestion : 2. Mechanical Grinding Down of Food Carnivore Teeth Pointed to facilitate holding and tearing of food © Clinical Textbook for Veterinary Technicians 6 th ed .; McCurnin, Bassert
  41. 41. Chronology of Digestion: 2. Mechanical Grinding Down of Food Herbivore Teeth Flat, occlusal surface for grinding
  42. 42. Chronology of Digestion: 2. Mechanical Grinding Down of Food <ul><li>Incisors – Teeth in the front for holding and tearing </li></ul><ul><li>Canines – Pointed teeth located at corners for tearing and shredding </li></ul><ul><li>Premolars – Located just before the molars and are used for grinding in all species </li></ul><ul><li>Molars – Used for grinding </li></ul>
  43. 43. Chronology of Digestion: 2. Mechanical Grinding Down of Food Ruminant Teeth No upper incisors or upper canine teeth Dental Pad Thick connective tissue Diastema
  44. 44. Chronology of Digestion: 2. Mechanical Grinding Down of Food Positional Location of Teeth - Terminology Maxilla Upper Arcade Mandible Lower Arcade Lingual Inner side of lower arcade teeth that face tongue Labial Outer surface of upper and lower arcade teeth (faces lips) Palatal Inner side of upper arcade teeth (faces the palate) Buccal Outer side of teeth in back of mouth (faces the cheeks)
  45. 45. Chronology of Digestion: 3. Chemical Digestion of Food <ul><li>Saliva mixes with food during chewing </li></ul><ul><li>Three bilateral pairs of salivary glands in the mouth ( parotid, mandibular, lingual ) </li></ul><ul><li>What saliva does: </li></ul><ul><ul><li>softens, moistens, shapes & lubricates food </li></ul></ul><ul><ul><li>aids in taste </li></ul></ul><ul><ul><li>acts as a buffer </li></ul></ul><ul><ul><li>provides digestive enzymes </li></ul></ul>
  46. 46. Chronology of Digestion 3. Chemical Digestion of Food <ul><li>Digestive enzymes and buffers in saliva </li></ul><ul><li>Amylase : in omnivore saliva – not carnivore breaks down amylose (sugar component of starch) </li></ul><ul><li>Lipase: breaks down lipids </li></ul><ul><li>Bicarbonate and Phosphate buffers: in cow saliva; neutralizes acids in rumen & maintain normal rumen pH ( up to 25-30 gallons of saliva a day) </li></ul>
  47. 47. Chronology of Digestion 3. Chemical Digestion of Food <ul><li>Epiglottis </li></ul><ul><ul><ul><li>Cartilage projection that prevents food from entering trachea </li></ul></ul></ul><ul><li>Esophagus </li></ul><ul><li>- transports food to stomach </li></ul><ul><ul><ul><li>Peristalsis: smooth muscle contractions to propel food </li></ul></ul></ul>
  48. 48. Chronology of Digestion 3. Chemical Digestion of Food <ul><li>Stomach </li></ul><ul><ul><ul><li>Stores food </li></ul></ul></ul><ul><ul><ul><li>Continues enzymatic breakdown of food (pepsin, gastrin, hydrochloric acid) </li></ul></ul></ul><ul><ul><ul><li>Mechanical breakdown of food (mixing, grinding and contractions that move food) </li></ul></ul></ul><ul><ul><ul><li>Ruminants: each compartment has different function </li></ul></ul></ul>
  49. 49. Chronology of Digestion 3. Chemical Digestion of Food <ul><li>Liver </li></ul><ul><ul><ul><li>Secretes bile acids to help with digestion of fat </li></ul></ul></ul><ul><li>Pancreas </li></ul><ul><ul><li>Secretes enzymes into small intestine for breaking down nutrients: </li></ul></ul><ul><ul><ul><ul><li>Protease for proteins </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Amylase for carbohydrates </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Lipase for fats/lipids </li></ul></ul></ul></ul><ul><ul><li>Also secretes bicarbonate to neutralize stomach acid </li></ul></ul>
  50. 50. Chronology of Digestion 4. Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>Duodenum, Jejunum, Ileum </li></ul></ul><ul><ul><li>Inner & sub mucosal layer; </li></ul></ul><ul><ul><ul><li>Muscular layer </li></ul></ul></ul><ul><ul><li>Villi & Microvilli increase surface area in intestine </li></ul></ul><ul><ul><li>Peristaltic waves help move contents through intestines </li></ul></ul>
  51. 51. Chronology of Digestion 4. Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>No clear demarcation between 3 segments </li></ul></ul><ul><ul><li>All 3 segments perform peristalsis, absorb nutrients & H 2 O </li></ul></ul><ul><ul><li>Duodenum: first portion of sm. intestine </li></ul></ul>Jejunum: majority of sm. intestine <ul><ul><li>Ileum: where sm. intestine enters colon </li></ul></ul>
  52. 52. Chronology of Digestion 4. Absorption of Nutrients & Water <ul><li>Villi </li></ul><ul><ul><li>Millions of cylindrical, fingerlike projections in intestinal wall </li></ul></ul><ul><ul><li>Provide large surface area for absorbing nutrients </li></ul></ul><ul><ul><li>“ Crypts” surround villi and replenish cells </li></ul></ul><ul><li>Microvilli “brush border” </li></ul><ul><ul><li>Found on Villi; contain digestive enzymes </li></ul></ul><ul><li>Transmissible Gastroenteritis (TGE) in pigs </li></ul><ul><li>Parvo Virus in dogs attack the villus </li></ul>Animal cannot absorb nutrients from intestinal tract
  53. 53. Chronology of Digestion 4. Absorption of Nutrients & Water <ul><li>Small Intestine </li></ul><ul><ul><li>Absorbs electrolytes (Na, Cl, K, etc.); water and vitamins across intestinal wall </li></ul></ul><ul><ul><li>Absorbs carbohydrates, fats, proteins after they’re chemically digested via enzymes </li></ul></ul>
  54. 54. Chronology of Digestion 4. Absorption of Nutrients & Water <ul><li>Nutrient digestion in the small intestine </li></ul><ul><li>Carbohydrates: digested by amylase secreted from pancreas </li></ul><ul><li>Protein: digested by proteases secreted by pancreas </li></ul><ul><li>Fat: digested by bile acids from liver (helps emulsify fat to prevent glob formation); further broken down by lipase secreted from pancreas </li></ul>
  55. 55. Chronology of Digestion 5. Elimination of Waste Material <ul><li>Large Intestine: Cecum & Colon </li></ul><ul><ul><li>Recover fluid and electrolytes </li></ul></ul><ul><ul><li>Store feces until elimination </li></ul></ul><ul><ul><li>Some microbial action </li></ul></ul><ul><ul><li>Differences between species, dependent on diet </li></ul></ul>
  56. 56. Chronology of Digestion 5. Elimination of Waste Material *Horses are different Colon Cecum “blind sac” Carnivores Simple, tubular, contracts to move feces through Poorly developed Herbivores* Large bacterial population (microbes) for fermentation More developed, larger than carnivore
  57. 57. Chronology of Digestion 5. Elimination of Waste Material <ul><li>Colon & Cecum comprise the “Hindgut” </li></ul><ul><li>4 sections: cecum, ventral colon, dorsal colon, small colon </li></ul><ul><li>More highly developed than small intestine </li></ul><ul><li>Has greater capacity for fermentation </li></ul><ul><li>Unique digestion path; colonic impaction is most common form of colic in horses </li></ul>
  58. 58. Chronology of Digestion 5. Elimination of Waste Material <ul><li>Rectum </li></ul><ul><ul><li>Terminal portion of colon </li></ul></ul><ul><ul><li>Contains mucus-secreting glands </li></ul></ul><ul><ul><li>Sensory receptors detect stretching/distension and triggers defecation </li></ul></ul><ul><li>Anus </li></ul><ul><ul><li>Internal & External sphincters allow controlled passage of feces </li></ul></ul>
  59. 59. Next Week… <ul><li>Session 2: </li></ul><ul><li>Basic Nutrients </li></ul>
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