1. Digestive System Overall Function Ingestion
Digestion (physical & chemical)
Absorption
Waste elimination

2. 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

4. Endoderm
Foregut
Midgut
Hindgut

6. General Morphology
Typical gut wall has MUCOSA, SUBMUCOSA, MUSCULARIS, SEROSA

8. Gut motility
Peristalsis
Segmentation

11. Oral cavity/Oropharyngeal cavity
Tongue – can extend from mouth beginning with amphibians
Anchored by hyoid
Helps to capture food, chew, swallow, taste food

13. Glands Venom Saliva Including several enzymes
Anticoagulant in lampreys
Nutrients in catfish
Mucus

14. Snake venoms Copy and paste URL to link to original images at BIODIDAC

16. Teeth
Dermal armor, dermal plates
Placoid scales
Homology to teeth

18. Teeth
Dentin forms the majority of tooth and is a bone-like material made by odontoblasts

20. Teeth
Enamel is the hardest substance in the body due to mineral content and is made by ameloblasts

22. Teeth
The pulp cavity of the tooth contains the blood vessels and nerves
The cementum covers the root of tooth and is made of acellular bone

24. Tooth attachment Acrodont – peak of jaws, teleosts
Pleurodont – inner surface of jaws, amphibians, lizards
Thecodont – sockets, crocodiles, extinct birds and mammals

26. Sets of teeth Polyphydont – many sets, typical of most vertebrates
Diphydont – two sets, most mammals
Monophydont – one set, platypus

28. Feeding
Teeth
New teeth forming

30. Shape of teeth
Homodont – fish, amphibians, most reptiles, some marine mammals

32. Shapes of teeth Heterodont – later reptiles, most mammals
Incisors - cutting teeth, chisel shaped
Canine teeth – pointed for piercing & tearing
Premolars – grinding teeth with 1-2 roots
Molars – grinding teeth with 3 roots

34. Dental formulas Human: 2-1-2-3/2-1-2-3 = 32 Cat: 3-1-3-1/3-1-2-1 = 30
Cow: / = 32

36. Key Points What do you find unusual about the cow’s dental formula?
What does this tell you about their eating habits?
Can you think of another animal that would have the same unusual feature?

38. Herbivore Copy and paste URL to link to original images at BIODIDAC

39. Pharynx Fish – respiratory (gill) in function
Tetrapods – throat, swallowing, location of tonsils in mammals

41. Pharynx in Tetrapods Common opening to airways via glottis
Opening to middle ear via auditory tubes
Opening to esophagus

42. Esophagus
Can close in fish so stomach doesn’t 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

44. Stomach Gastr- Anatomy –one or more chambers
Pylorus, pyloric sphincter
Greater & Lesser curvature
Greater omentum, mammals only

47. Stomach
Proventriculus – Contains digestive enzymes in birds (& crocodiles)
Gizzard –grinding mill in bird

50. Ruminant Stomachs Rumen – cellulase & mucus release
Reticulum – bolus formation for regurgitation
Omasum – holding tank
Abomasum – glandular portion

53. 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

55. Stomach Physiology
Most gastric secretions come from the goblet cells which make mucus to protect the lining of the stomach from its contents

56. Intestine Fish Straight No small & large intestine
Typhlosole = spiral valve
Coils
Cecum/cecal

57. Digestive system
Stomach
Spiral valve

59. Intestine in Tetrapods
Small Intestine
Duodenum –mammals
Jejunum –mammals
Ileum –mammals
Villi to increase surface area
Blood vessels & lacteals for absorption

62. Small Intestine Function
Finish chemical digestion
Most nutrient absorption occurs in small intestine

63. Key Points
Name two anatomical features that supports the function of the small intestine

64. 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

67. 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

68. Key Point
What are diverticula?
What does the root “cyst-” mean?

70. 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

72. 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?

73. Pancreas
Exocrine portion makes digestive juices that travel through pancreatic duct
Acinar cells are the exocrine cells
Juice contains amylase, lipase, protease

75. Key Points
What does the pancreas make besides the exocrine juices?

76. Cloaca
Receives digestive, urinary and genital structures below placental mammals

78. Key Points
Name the four stomachs of the ruminant.