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									                                       BIOLOGY 453 - COMPARATIVE VERT. ANATOMY
                                          LAB 12 - DIGESTIVE SYSTEM - GUT LAB
      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
Australian Museum Fish Site. 2009. Student Stuff: Fish Dissections.
Birch Aquarium. 2007. Shark Dissection Webcast. Univ. California, San Diego
Canadian Shark Research Laboratory. 2005. Internal Anatomy
Pepe, P. 2006. Virtual Shark Lab, Activity 2: Digestive System. Phoenix College.
Bowen, R. 2003. Digestive Physiology of Birds. Pathophysiology of the digestive system. Colorado State Univ.
Caceci, T. 2006. Exercise 22: Avian Digestive System. VM8054 Veterinary Histology. Virginia-Maryland Reg. Coll. of Vet. Medicine.
Derting, T. 2002. Digestive System. Murray State Univ.
            Wood Duck
            Canvasback Duck
Bowen, R. 2003. Digestive Anatomy in Ruminants. Pathophysiology of the Digestive System. Colorado State Univ.
Caceci, T. 2008. Exercise 21: Ruminant Digestive System. VM8054 Veterinary Histology. Virginia-Maryland Regional Coll. of Vet. Medicine.
Slomianka, L. 2009. Blue Histology - Oral Cavity and Oesophagus. Univ. of Western Australia, School of Anatomy & Human Biol.
Strauss, J.A. 1998. Digestive System, Biol. 29. Penn. State Univ.
Wells, P. 2000. Rabbit Images: Thumbnails. Vert. Anatomy Page, Bishops College.

                                                                 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
                                                        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


      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


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

                                                                                                                       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


  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.


                                                                                    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

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