Digestive System
Origin
• Stomodeum and Proctodeum
• Buccopharyngeal membrane and cloacal membrane
Major Components
• Digestive Tract
• Buccal Cavity
• Pharynx
• Alimentary Canal
• Accessory Glands
Components: Buccal Cavity
• Teeth, tongue, palate
• Functions: Mechanical and chemical breakdown
Components: Buccal Cavity - Palate
• Roof of the mouth
• Primary Palate: contains internal nares
• Medial series: Vomer, Pterygoid, Parasphenoid
• Lateral series: Palatine, Ectopterygoid
• Secondary Palate: some reptiles and mammals
• Hard and soft palate
Components: Buccal Cavity - Teeth
• Origin: ectodermal
• Mechanical breakdown, holding, hunting
Components: Buccal Cavity - Tongue
• Evolution: Hypobranchial muscles resting on Hyoid Apparatus
• Sensory, feeding
Components: Buccal Cavity - Tongue
• Ingestion
• Intraoral transport
• Deglutition - swallowing
Components: Buccal Cavity - Tongue
• Lingual feeding
Components: Pharynx
• Common passage for food and air
• Derivatives: Pharyngeal pouches meeting with branchial grooves,
further developing into other organs
Components: Pharynx
• Swallowing/Deglutition
• Air vs food
Components: Alimentary Canal
• Esophagus
• Stomach
• Small Intestine
• Large Intestine
• Terminus: Cloaca or Anus
Alimentary Canal Design
• Mucosa, submucosa, muscularis externa, adventitia
Alimentary Canal Origin
• Endoderm – lining
• Mesoderm – muscles, CT, BV
Alimentary Canal Components: Esophagus
• Distendible, secretes mucus
• Modifications: for abrasion (histologic), for large amounts of food
(histologic and behavioural)
Alimentary Canal Components: Stomach
• Storage, absorption, digestion
• Gastric juice – HCl, mucus, enzymes
• Rugae
• Sections:
• Cardiac – mucus
• Fundus – Parietal and Chief cells
• Pylorus – Neutralize, mucus
Alimentary Canal Components: Small
Intestine
• Villi, Microvilli (absorption)
• Crypts of Lieberkuhn (enzymatic)
• Intestinal juice
• Duodenum, jejunum, ileum
• Duodenum – pancreatic and hepatic
secretions, Brunner’s glands
(neutralize)
• Jejunum
• Ileum – ileocolic valve
Alimentary Canal Components: Large
Intestine
• Simple columnar, terminus: stratification
• Internal and external anal spinchther
Accessory Glands
• Oral Glands
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Buccal cavity
Mucus and serous fluid
More common in tetrapods
Examples: Salivary glands, lacrimal glands, venom glands
Accessory Glands
• Liver
• Developmental: RBC production
• Adults: RBC destruction, filtering of wastes, bile production (exocrine)
• Origin: hepatic diverticulum
Accessory Glands
• Pancreas
• Origin: Dorsal and ventral pancreatic diverticulum
• Ducts lead to duodenum, contains trypsin and chymotrypsin (exocrine)
• Islets of Langerhans: insulin and glucagon (endocrine)
Adaptations and Specializations of the GI
• Fish:
• Ileal modification – spiral valve – primitive osteichthyans, elasmobranches
• Rectal gland - sharks
• Pyloric cecum/ceca (absorption) - osteichthyes
Adaptations and Specializations of the GI
• Terrestrial Vertebrates
Adaptations and Specializations of the GI
• Gizzards
Adaptations and Specializations of the GI
• Extended ceca
Adaptations and Specializations of the GI
• Coprophagia
Images
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http://www.perinatology.com/images/primarypalate.jpg
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http://www.anatomyatlases.org/MicroscopicAnatomy/Images/Plate192.jpg
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http://www.walgreens.com/marketing/library/graphics/images/en/1121.jpg
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http://www.zoology.ubc.ca/~millen/oldvertebrate/spiral20valve.jpg
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http://1.bp.blogspot.com/_W19ZkFqGTM/Sz2ri8ZKWiI/AAAAAAAADZI/MdwPyTQFogI/s400/Cows%2Bteeth%2BFM%2Bgood.jpg
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http://health.rush.edu/healthinformation/graphics/images/en/15873.jpg
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http://courses.washington.edu/vertebra/452/photos/amphib/giant_toothrow.jpg
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http://2.bp.blogspot.com/_euq4iPQ9iQk/TKNkGaP5KPI/AAAAAAAACfQ/HKzE6_pek9c/s400/Chicken%2BG
izzards%2BScreen%2BSaver.jpg
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http://3.bp.blogspot.com/•
xv3NJkxbs68/UGs9bygAySI/AAAAAAAAB1Q/MTv8jiK0lb8/s1600/Animal%2Battacks%2Bnews%2Bdangero
us%2Banimal%2Bteeth%2Bof%2Bhyena%2Bdangerous%2Banimals%2Bof%2Bkenya%2Bsouth%2Bafrica%2•
Btanzania%2Bzimbabwe%2Banimal%2Bpictures.jpg
http://bio1152.nicerweb.com/Locked/media/ch41/41_27GITractComparison_CL.jpg
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http://www.peteducation.com/images/articles/ill_reptile_teeth.gif
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http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/pregastric/cheekteeth.jpg
http://4.bp.blogspot.com/_zHWK8oRfUrU/TS_4jcpKQfI/AAAAAAAABfg/yqO5lgn8nKY/s1600/DSC_0010.JP
G
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http://www.patzner.sbg.ac.at/Gobiidae/Fotos/Gob_buc_6.jpg
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http://1.bp.blogspot.com/XTvsIwo9ouk/ToUu3JKafPI/AAAAAAAAGCs/Ussb_Yxaq2U/s1600/EBV%2BPythonBunny7.jpg
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http://sharkmans-world.eu/images/teeth.jpg
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http://courses.washington.edu/chordate/453photos/gut_photos/fundus_esophagus.jpg
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http://www.tigerhomes.org/animal/images/diamondback-teeth.jpg
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http://www.aps.uoguelph.ca/~swatland/s140.gif
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http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/Web/gondwana/Animal_Fossils_of_Gondwana/lo/fossi •
ls_06/graphics/tooth1.jpg
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http://www.neuro.fsu.edu/~mmered/vomer/images/Snake.gif
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http://courses.washington.edu/chordate/453photos/gut_photos/fundus_esophagus.jpg
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http://www.wild-facts.com/wp-content/uploads/2009/10/cheats-chameleon.jpg
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http://www.aps.uoguelph.ca/~swatland/s140.gif
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http://kuwaitiful.com/wp-content/uploads/2011/04/cats-tongue-close-up-magnifiy.jpg
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http://rsbl.royalsocietypublishing.org/content/early/2011/05/23/rsbl.2011.0336/F2.large.jpg
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http://sepetjian.files.wordpress.com/2011/10/embryoes2116.jpg
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http://methiscool.files.wordpress.com/2012/04/21_04bhumandigestivesys-l.jpg
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http://blogs.bu.edu/bioaerial2012/files/2012/09/Pelican-Wins1.jpg
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http://us.123rf.com/400wm/400/400/CathyKeifer/CathyKeifer1101/CathyKeifer110100004/8537840-abog-eyed-tree-frog-is-trying-to-catch-a-fly-with-his-tongue.jpg
http://reptilis.net/index4/swallow2.jpg
http://naturallycuriouswithmaryholland.files.wordpress.com/2012/01/1-19-12-snowshoe-hare-scatimg_7235.jpg
http://1.bp.blogspot.com/XTvsIwo9ouk/ToUu3JKafPI/AAAAAAAAGCs/Ussb_Yxaq2U/s1600/EBV%2BPythonBunny7.jpg