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Comparative Anatomy Digestive System Note Set 11 Chapter 13.

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Presentation on theme: "Comparative Anatomy Digestive System Note Set 11 Chapter 13."— Presentation transcript:

1 Comparative Anatomy Digestive System Note Set 11 Chapter 13

2 Digestive System Six major subdivisions Oral cavity Oral cavity Pharynx Pharynx Esophagus Esophagus Stomach Stomach Small & large intestine Small & large intestine Rectum Rectum

3 Digestive System Agnatha - straight digestive tube Agnatha - straight digestive tube Coiled tube evolved with lengthening of tract Coiled tube evolved with lengthening of tract Figure 11.1: Simple to complex digestive systems.

4 Oral Cavity Begins at mouth, ends at pharynx Begins at mouth, ends at pharynx Tongue in floor of cavity Tongue in floor of cavity Palate in roof of cavity Palate in roof of cavity Primary palate Primary palate Secondary palate Secondary palate Teeth Teeth Figure 11.2: Human oral cavity.

5 Palates Primary palate in anamniotes- nasal passageways empty into oral cavity Primary palate in anamniotes- nasal passageways empty into oral cavity Ex: Salamander Ex: Salamander Secondary palate of amniotes- extends to pharyngeal cavity Secondary palate of amniotes- extends to pharyngeal cavity Internal nares Internal nares Figure 11.3: Oral cavity of amphibian (a) and mammal (b).

6 Teeth On jaws normally On jaws normally Cheeks in mammals form pocket Cheeks in mammals form pocket Acrodont teeth- fish and snakes Acrodont teeth- fish and snakes Bicuspid- amphibians Bicuspid- amphibians Tricuspid- lizards Tricuspid- lizards Pleurodont teeth- snakes Pleurodont teeth- snakes Thecodont teeth- Thecodont teeth-crocodilians Figure Cross section of jaw. Figure Types of cusps.

7 Jaw Teeth and Cheek Used for storage- rodents and squirrels Used for storage- rodents and squirrels Modified placoid scales- sharks Modified placoid scales- sharks Polyhyodont- permanent replacement of teeth Polyhyodont- permanent replacement of teeth Diphyodont- two sets of teeth Diphyodont- two sets of teeth Monophyodont- one set of teeth Monophyodont- one set of teeth

8 Bird Teeth Egg caruncle- all egg layers Egg caruncle- all egg layers Not actual tooth Not actual tooth Structure epidermal, horny, keratinized Structure epidermal, horny, keratinized On tip of snout On tip of snout To penetrate egg shell To penetrate egg shell Figure 11.6: Egg caruncle of 15 day old owlet.

9 Reptilian Teeth Egg tooth- lizards and snakes Egg tooth- lizards and snakes Actual tooth Actual tooth Upper jaw Upper jaw To penetrate egg shell To penetrate egg shell Figure 11.7: Monitor egg tooth..

10 Aglyphous- no modifications for venom delivery Aglyphous- no modifications for venom delivery Solenoglyphous- retractable teeth, fangs Solenoglyphous- retractable teeth, fangs Proteroglyphous- fangs in front of mouth Proteroglyphous- fangs in front of mouth Opisthoglyphous- fangs in back of mouth Opisthoglyphous- fangs in back of mouth Modifications of Snake Teeth Figure 11.8: Position, cross and longitudinal sections of aglyphous (1), opisthoglyphous (2), and solenoglyphous (3) fangs.

11 Incisors Incisors For cutting For cutting Ex: elephant tusks Ex: elephant tusks Canines Canines For piercing For piercing Ex: walrus tusks Ex: walrus tusks Premolars & Molars Premolars & Molars To matriculate food To matriculate food Diastema- space without teeth; e.g., no canines Diastema- space without teeth; e.g., no canines Figure 11.9: Mammalian teeth specializations. Mammalian Teeth

12 Heterodont dentition Heterodont dentition Other varieties Other varieties Homodont- all teeth the same Homodont- all teeth the same Bunodont- all teeth on single plain Bunodont- all teeth on single plain Sectorial teeth – carnassials; e.g., upper premolar and lower molar in carnivores Sectorial teeth – carnassials; e.g., upper premolar and lower molar in carnivores

13 Dental Formula Figure 11.10: Dental formulae. Catarrhines and humans have Catarrhines and humans have =16 x 2 = 32 total teeth Canines: and Canines: and If 0 is present, diastema is present If 0 is present, diastema is present

14 Tongue Immobile in jawed fish Immobile in jawed fish Fleshy in higher vertebrates Fleshy in higher vertebrates Frog- tongue shoots out and draws back Frog- tongue shoots out and draws back Glandular field secretes sticky fluid Glandular field secretes sticky fluid Immobile tongue- turtles, crocs, and some birds Immobile tongue- turtles, crocs, and some birds Flexible tongue- nectar feeding bats and snakes Flexible tongue- nectar feeding bats and snakes Forked tongue of snake Forked tongue of snake Figure 11.11: Jacobsons organ (sensing apparatus) of snake and forked tongue.

15 Oral Glands Named based on location Named based on location Labial- near the lips Labial- near the lips Palatal- near palate Palatal- near palate Internasal Internasal Sublingual- releases venom Sublingual- releases venom Parotid- salivary gland Parotid- salivary gland Submaxillary Submaxillary Birds have few oral glands Birds have few oral glands Swifts Swifts Figure 11.12: Swift and nest.

16 Pharynx In embryo, exhibits series of lateral pharyngeal pouches In embryo, exhibits series of lateral pharyngeal pouches Gives rise to various glands Gives rise to various glands Slits in pharyngeal region Slits in pharyngeal region Figure 11.13: Embryonic pharyngeal arches and oral development. Figure 11.14: Adult regions of pharynx.

17 Constant Features in Tetrapods Constant Features in Tetrapods Glottis-slit to larynx Glottis-slit to larynx Covered by epiglottis Covered by epiglottis Eustachian tube- opening Eustachian tube- opening Esophagus- opening Esophagus- opening Pharynx further subdivided for food and air passage Pharynx further subdivided for food and air passage Foramen cecum- groove on back of tongue Foramen cecum- groove on back of tongue Vestigial structure the leads to embryonic thyroid gland Vestigial structure the leads to embryonic thyroid glandPharynx

18 Pharynx Figure 11.15: (a) Upper respiratory tract of human showing pharynx regions and (b) hyoid and larynx.

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20 Esophagus Muscular tube connecting pharynx and stomach Muscular tube connecting pharynx and stomach Can be short Can be short Crop- specialization in birds Crop- specialization in birds Outpocketing of esophagus Outpocketing of esophagus Used to store food Used to store food Pigeons milk Pigeons milk Figure 11.16: Esophagus and crop of bird.

21 Stomach Muscular chamber Muscular chamber Secretes gastric juices Secretes gastric juices Different lining of stomachs Different lining of stomachs Esophageal-like epithelia Esophageal-like epithelia Glandular epithelia Glandular epithelia Ruminant stomach Ruminant stomach 4 chambers: rumen, reticulum, omasum, abomasum 4 chambers: rumen, reticulum, omasum, abomasum Human stomach Human stomach Cardiac sphincter- esophagus Cardiac sphincter- esophagus meets stomach Mostly lined with gastric epithelium Mostly lined with gastric epithelium Figure 11.17: Stomach of mammals with esophageal-like epithelia in gray and glandular epithelia in red.

22 Stomach Structure Greater and lesser curvature Greater and lesser curvature Messentaries Messentaries Greater omentum – attaches along greater curvature Greater omentum – attaches along greater curvature Lesser omentum – attaches along lesser curvature Lesser omentum – attaches along lesser curvature Cecum- increases surface area Cecum- increases surface area 2 parts in bird and crocodile stomach 2 parts in bird and crocodile stomach Proventiculus-glandular Proventiculus-glandular Gizzard- grinding mill (gastroliths) Gizzard- grinding mill (gastroliths)

23 4-Chambered Stomachs Figure 11.18: Stomach of calf. Rumen- food enters Rumen- food enters Bacterial action Bacterial action Reticulum- forms a bolus Reticulum- forms a bolus Omasum- reswallowed grass Omasum- reswallowed grass Salivary action Salivary action Abomasum- food worked out by gastric glands Abomasum- food worked out by gastric glands

24 Small Intestine Duodenum- 1 st segment Duodenum- 1 st segment Bile and pancreatic ducts Bile and pancreatic ducts Jejunum and Ileum subdivisions Jejunum and Ileum subdivisions Figure 11.19: Digestive tract showing regions of small intestine.

25 Brunners Glands- mucous glands in duodenum and jejunum Brunners Glands- mucous glands in duodenum and jejunum Peyers Patches- lymphatic nodules in ileum Peyers Patches- lymphatic nodules in ileum Crypts of Lieberkühns- intestinal glands at base of villi Crypts of Lieberkühns- intestinal glands at base of villi Lacteals- within villiinterior lymphatic vessels Lacteals- within villiinterior lymphatic vessels Transport fat molecules to circulatory system Transport fat molecules to circulatory system Valve of Kirckring- increases surface area Valve of Kirckring- increases surface area Small Intestine

26 Figure 11.20: Histology of alimentary canal of a mammal showing various glands of small intestine.

27 Large Intestine Fish and amphibians - straight and short Fish and amphibians - straight and short Amniotes- divided into colon and rectum Amniotes- divided into colon and rectum Ileocecal valve- allows passage from small intestine into large Ileocecal valve- allows passage from small intestine into large Sigmoid flexure- S-shaped region Sigmoid flexure- S-shaped region at rectum at rectum Cecum- aids in absorption Cecum- aids in absorption Terminates at vermiform appendix Terminates at vermiform appendix Cloaca- common chamber for Cloaca- common chamber for digestive, urinary, and reproductive products to empty (includes monotremes) Figure 11.21: Large intestine of human.

28 Liver Liver is diverticulum of primitive gut Liver is diverticulum of primitive gut Liver produces bile Liver produces bile Bile stored in gallbladder Bile stored in gallbladder Common bile duct Common bile duct Ampulla of Vater- terminal portion Ampulla of Vater- terminal portion Figure 11.22: Development of liver and pancreas.

29 Pancreas Pancreas – diverticulum of gut Pancreas – diverticulum of gut Duct of Santorini- small, dorsal pancreas Duct of Santorini- small, dorsal pancreas Duct of Wirsung- large, ventral pancreas Duct of Wirsung- large, ventral pancreas Accessory duct- large duct after small, dorsal duct disappears Accessory duct- large duct after small, dorsal duct disappears Exocrine and endocrine glands Exocrine and endocrine glands Islets of Langerhans- endocrine glands Islets of Langerhans- endocrine glands

30 Rectal gland- diverticulum in sharks Rectal gland- diverticulum in sharks

31 Figure 11.1, 11.3, 11.4, 11.5, 11.10, 11.15, 11.16, 11.17, & Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, Figure.2- Figure Figure.6- Figure Figure.7- Figure Figure.8- Figure Figure.9- Figure Figure.11- Figure Figure.12- Figure Figure.13- Figure Figure.14- Figure Figure.19- Figure Figure.20- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, Figure Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, Figure - Figure Literature Cited


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