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, Brunners glands (neutralize) Jejunum Ileum ileocolic valve Alimentary Canal Components: Large Intestine Simple columnar, terminus: stratification Internal and external anal spinchther Accessory Glands Oral Glands 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 ImagesM/Sz2ri8ZKWiI/AAAAAAAADZI/MdwPyTQFogI/s400/Cows%2Bteeth%2BFM%2Bgood.jpg 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 ls_06/graphics/tooth1.jpg izzards%2BScreen%2BSaver.jpg img_7235.jpgGGXTvsIwo9ouk/ToUu3JKafPI/AAAAAAAAGCs/Ussb_Yxaq2U/s1600/EBV%2BPythonBunny7.jpgXTvsIwo9ouk/ToUu3JKafPI/AAAAAAAAGCs/Ussb_Yxaq2U/s1600/EBV%2BPythonBunny7.jpgbog-eyed-tree-frog-is-trying-to-catch-a-fly-with-his-tongue.jpg