Presentation on theme: "Digestive System Overall Function Ingestion Digestion (physical & chemical) Absorption Waste elimination."— Presentation transcript:
Digestive System Overall Function Ingestion Digestion (physical & chemical) Absorption Waste elimination
Development Coelom forms from splitting of lateral plate mesoderm (hypomere) This is the pleuroperitoneal cavity through reptiles Parietal peritoneum Visceral peritoneum Dorsal & Ventral mesentery are folds of peritoneum
Endoderm Foregut Midgut Hindgut
General Morphology Typical gut wall has MUCOSA, SUBMUCOSA, MUSCULARIS, SEROSA
Gut motility Peristalsis Segmentation
Oral cavity/Oropharyngeal cavity Tongue – can extend from mouth beginning with amphibians Anchored by hyoid Helps to capture food, chew, swallow, taste food
Glands Venom Saliva Including several enzymes Anticoagulant in lampreys Nutrients in catfish Mucus
Key Points What do you find unusual about the cows dental formula? What does this tell you about their eating habits? Can you think of another animal that would have the same unusual feature?
Pharynx Fish – respiratory (gill) in function Tetrapods – throat, swallowing, location of tonsils in mammals
Pharynx in Tetrapods Common opening to airways via glottis Opening to middle ear via auditory tubes Opening to esophagus
Esophagus Can close in fish so stomach doesnt become filled with respiratory water Birds may have CROP – sometimes has digestive enzymes & allows hoarding of food Pigeon milk is an esophageal secretion in doves for nestlings
Stomach Gastr- Anatomy –one or more chambers Pylorus, pyloric sphincter Greater & Lesser curvature Greater omentum, mammals only
Stomach Proventriculus – Contains digestive enzymes in birds (& crocodiles) Gizzard –grinding mill in bird
Stomach Physiology Receives, stores, liquefies, mixes food Chyme Zymogenic cells make pesinogen which breaks down protein Parietal cells make HCl which breaks down protein, activates pepsinogen & is anti- microbial
Stomach Physiology Most gastric secretions come from the goblet cells which make mucus to protect the lining of the stomach from its contents
Intestine Fish Straight No small & large intestine Typhlosole = spiral valve Coils Cecum/cecal
Digestive system Stomach Spiral valve
Intestine in Tetrapods Small Intestine – Duodenum –mammals – Jejunum –mammals – Ileum –mammals – Villi to increase surface area – Blood vessels & lacteals for absorption
Small Intestine Function Finish chemical digestion Most nutrient absorption occurs in small intestine
Key Points Name two anatomical features that supports the function of the small intestine
Large Intestine in Tetrapods Cecum/ceca may be present in amniotes Colon is the majority of large intestine Rectum is the terminal segment of large intestine Function is formation & storage of feces, some water reabsorption, fermentation in herbivores
Liver & Gall Bladder Embryology – formed from diverticula of foregut and midgut Lesser omentum supports ducts & vessels & travels from lesser curvature of stomach to liver Bile duct – Common Bile Duct is formed by hepatic and cystic ducts & goes to duodenum
Key Point What are diverticula? What does the root cyst- mean?
Liver & Gall bladder Falciform ligament – liver to ventral body wall Function includes glucose storage, bile secretion, amino acid deamination, clotting factors, blood formation in fish Gall bladder store bile
Key Points You are investigating why hundreds of birds in a certain location died. You primarily are interested in conducting tests on the liver. Why? What would this tell you?
Pancreas Exocrine portion makes digestive juices that travel through pancreatic duct Acinar cells are the exocrine cells Juice contains amylase, lipase, protease
Key Points What does the pancreas make besides the exocrine juices?