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BIOLOGY 453 - COMPARATIVE VERT. ANATOMY LAB 12 - DIGESTIVE SYSTEM - GUT LAB GOALS 1. Know the taxa, clades & shared derived traits listed in the table below. 2. Know at least 1 unique function for these parts of the digestive system as described in lab manual or text: a. palatal rugae, fleshy lips, muscular tongue, peritoneal membranes, esophagus, crop (in bird), stomach, pyloric sphincter, proventriculus (of bird stomach), gizzard (of bird stomach), liver, gall bladder, pancreas, small intestine (spiral valve type in shark), large intestine, cecum (in rabbit), rectal gland (in sharks). 3. Identify the 3 salivary glands in the cat: parotid, submaxillary or submandibular & sublingual. Know the type of fluid each produces. 4. Be able to identify other GI tract structures as noted, for the shark, bird, rabbit & cat. 5. Compare the length of the shark, bird & cat intestines. How does a shark increase surface area for digestion in the intestines if their intestine is so short? Why are the bird's intestines so much shorter than a comparable sized mammal's intestines? 6. What unique features are found in the bird digestive tract? What features are specialized for a granivorous (seed) diet in the birds? 7. Which parts of the rabbit digestive tract are specialized for processing plant material? 8. Is the rabbit a foregut or hindgut fermenter? Is the cow a foregut or hindgut fermenter? 9. Know the functions of the 4 regions in a cow/sheep (ruminants) stomach: rumen, reticulum, omasum & abomasum. Type of Material Specimens to Examine preserved, whole animal shark, alligator, birds, cat, rabbit preserved organs rabbit viscera, cow & goat ruminant stomachs Additional Sources of Information Topic General Shark GI Bird GI Mammal GI Cavities, Membranes Kardong & Zalisko pg. 130 130-134 131 137-144 Fishbeck & Sebastiani pg. 57-60 159-165 355-366 55-56, 343-347 ACTINOPTERYGII (BONY FISH) & CHONDRICHTHYES (SHARKS) Australian Museum Fish Site. 2009. Student Stuff: Fish Dissections. http://www.austmus.gov.au/fishes/students/dissections.htm Birch Aquarium. 2007. Shark Dissection Webcast. Univ. California, San Diego http://aquarium.ucsd.edu/Education/Learning_Resources/Shark_Dissection_Webcast/ Canadian Shark Research Laboratory. 2005. Internal Anatomy http://www.marinebiodiversity.ca/shark/english/internal%20anatomy.htm Pepe, P. 2006. Virtual Shark Lab, Activity 2: Digestive System. Phoenix College. http://www.pc.maricopa.edu/Biology/ppepe/BIO145/lab04_2.html BIRDS Bowen, R. 2003. Digestive Physiology of Birds. Pathophysiology of the digestive system. Colorado State Univ. http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/birds/index.html Caceci, T. 2006. Exercise 22: Avian Digestive System. VM8054 Veterinary Histology. Virginia-Maryland Reg. Coll. of Vet. Medicine. http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab22/Lab22.htm Derting, T. 2002. Digestive System. Murray State Univ. Wood Duck http://campus.murraystate.edu/academic/faculty/terry.derting/cva_atlases/jaymejohn/digestive1.html Canvasback Duck http://campus.murraystate.edu/academic/faculty/terry.derting/cva_atlases/canduck/digestsysduck.htm MAMMALS Bowen, R. 2003. Digestive Anatomy in Ruminants. Pathophysiology of the Digestive System. Colorado State Univ. http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumen_anat.html Caceci, T. 2008. Exercise 21: Ruminant Digestive System. VM8054 Veterinary Histology. Virginia-Maryland Regional Coll. of Vet. Medicine. http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab21/Lab21.htm Slomianka, L. 2009. Blue Histology - Oral Cavity and Oesophagus. Univ. of Western Australia, School of Anatomy & Human Biol. http://www.lab.anhb.uwa.edu.au/mb140/CorePages/Oral/oral.htm Strauss, J.A. 1998. Digestive System, Biol. 29. Penn. State Univ. http://www.bio.psu.edu/faculty/strauss/anatomy/digest/digestiv.htm Wells, P. 2000. Rabbit Images: Thumbnails. Vert. Anatomy Page, Bishops College. http://www.bishops.k12.nf.ca/wells/verts/rabbit/thumbs/thumbs.htm Taxonomy & Clades Subphylum Vertebrata or Craniata Class Chondrichthyes: sharks Clade Gnathostomata: sharks & up. Shared derived trait: stomach. Clade Tetrapoda: tetrapods. Shared derived trait: large intestine. Superorder Archosauria: alligator Clade Archosauria: alligator, birds. Shared derived traits: gizzard-like stomach. Class Aves: birds Class Mammalia: cat, rabbit... Clade Mammalia: cat, rabbit, cow, goat. Shared derived traits: fleshy lips CLASS CHONDRICHTHYES: Dogfish Shark Shark GI Tract Find the following digestive system structures in your shark this week. Pleuroperitoneal = peritoneal cavity, parietal & visceral peritoneum, falciform ligament, dorsal & intestinal mesenteries. Liver & Gall Bladder Pancreas is in 2 sections Spleen Stomach Fundic region of stomach (rugae) & Esophagus (papillae) Dorsal Mesentery, Spleen & Rectal gland. Next week you can locate the esophagus & examine the oral & pharyngeal cavities. Skate Digestive System Skate Mouth & Nostrils Liver retracted stomach Pancreas Gall bladder Liver Valvular Intestine Stomach Ovary SUBORDER ARCHOSAURIA: Alligator Demo Identify the following parts of the digestive system of the alligator for comparisons with the birds: Esophagus, stomach, "gizzard" region, small intestines, large intestines. Compare the alligator stomach design with the pigeon. Are they similar? Alligator Stomach Interior Alligator Stomach Exterior Digestive System Rock Dove Caiman Stomach Bird Stomach CLASS AVES: Pigeon, Chicken Identify the following parts of the digestive system of the pigeon: Esophagus, crop, stomach, proventriculus (part of stomach), gizzard (part of stomach), small intestine, cecae, large intestine. Esophagus, crop & trachea in view. Stomach: Proventriculus & Gizzard crop Liver removed to show intestines, pancreas. Cecae (paired) & Large Intestine Gizzard CLASS MAMMALIA Salivary Glands Human saliva is 99.5% water with some digestive enzymes (salivary amylase) and other solutes. It has a pH of 6-7 that neutralizes the acids produced by bacteria. If saliva is absent, the teeth are more prone to decay from bacterial action. All salivary glands use eccrine/merocrine type secretion. These glands are alveolar or cup shaped rather than tubular. Cat Salivary Glands: Arrows below are along the throat & point in the anterior or rostral direction. Large, whitish parotid gland (P) extends up on the side of the head going The L designates a lymph node. This view is of the left side of under the ear. The submandibular (=submaxillary) (SM) gland is near the the head, with the cat lying face up. lymph nodes (L) along the throat. It is round or nearly triangular shape. Left side of head, with ear is hidden by pealed back skin. L masseter P SM SM masseter P Ear is hidden by pealed back skin Cat Oral Cavity: Find the Oral cavity, palatal rugae, fleshy lips & muscular tongue. Next week we’ll locate the esophagus. Cat Peritoneal Cavity & Associated Membranes Identify the parietal peritoneum, visceral peritoneum, falciform ligament, greater omentum & intestinal mesenteries. Greater omentum Spleen Stomach Liver Gall bladder Falciform Ligament Liver Diaphragm Pancreas alongside duodenum Pancreas near spleen (behind greater omentum) Cat Digestive System Organs Identify the stomach, pyloric sphincter, liver, gall bladder, pancreas, small intestine, ileocolic sphincter, cecum & large intestine. The small intestine is divided into 3 sections; the first is called the duodenum. This is very short in most mammals (but not humans) & includes just the area where the pancreas & bile ducts empty into the intestines. The second region is called the jejunum & this may comprise up to 90% of the length of the intestines. The final section is the ileum the final loop that leads into the large intestine at the ileocolic sphincter. Cat stomach with pyloric sphincter & duodenum Stomach interior showing rugae folds Small Intestine (Jejunum) & Intestinal Mesenteries Cecum Ileocolic junction & Large Intestine HERBIVORE SPECIALIZATIONS Hindgut Fermentation - Rabbit Demo The rabbit has a larger stomach than the cat to store large amounts of grasses. It has a longer small intestine and a very long & "sac-like" cecum for hindgut fermentation of grasses. Within the cecum, bacteria digest cellulose by a fermentation process. The rabbit absorbs some of these metabolic products produced by the bacteria. Rabbits need to ingest "green" feces (cecotrophs) for a second fermentation cycle to acquire enough caloric value from their food, but larger hindgut fermenters such as horses do not. We have 1-2 rabbits with intact digestive systems along with lots of "pieces" of the digestive system from other rabbits. Identify: esophagus, stomach, liver, pancreas, small intestine (duodenum & ileum regions), cecum & large intestine. Rabbits have very large stomachs because cecotrophs are Three different sections of the rabbit intestines are in view. Large stored here before they are passed for a second time through intestine (LI), small intestine (SI) & cecum (CE). They all meet the intestines. at the ileocolic junction. Esophagus SI CE Stomach LI Duodenum & Pancreas Most of the rabbit cecum is large & sac-like but it ends with the Rabbit GI System thin “appendix” like structure at the lower left. Foregut Fermentation: Ruminant Stomach Demo (Cow & Goat) Cows, sheep & goats are herbivorous mammals that have a specialized, ruminant stomach that is used for fermentation (bacterial digestion) of plant cellulose. This is called foregut fermentation. Their stomachs are divided into 4 specialized chambers as noted in table. Some other herbivores (kangaroo, camel) mimic the ruminant stomach design, but these other taxa develop only 2-3 chambers rather than the 4-chambered design of ruminant mammals. Identify these 4 chambers & know 1 function for each chamber. ID the esophagus, pyloric sphincter & duodenum. Cow stomach with esophagus & part of duodenum. Last section of the Abomasum chamber of the cow stomach. Duodenum Pyloric sphincter Rumen [ = throat] Reticulum [ reicul = network] 1st chamber; largest, small villi; Bacterial fermentation of cellulose 2nd; small with reticular surface; packs undigested food into cud Omasum [ = pauch] Abomasum [ ab = off] 3rd; long “sheet-like folds; reabsorbs water from digested food 4th; rugae folds; “normal” acid & pepsin digestion begins Reticulum & Omasum of a Goat Abomasum of a goat
"BIOLOGY COMPARATIVE VERT ANATOMY LAB DIGESTIVE SYSTEM"