CA Section 13- Digestive System (Chapter 13) [EDocFind.com]

8/13/2019 CA Section 13- Digestive System (Chapter 13) [EDocFind.com]

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Comparative AnatomyDigestive System

Note Set 11

Chapter 13


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Digestive System

Six major subdivisions

Oral cavity

Pharynx Esophagus

Stomach

Small & large intestine Rectum


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Digestive System

Agnatha - straightdigestive tube

Coiled tube evolved withlengthening of tract

Figure 11.1: Simple to complex digestivesystems.


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Oral Cavity

Begins at mouth, ends atpharynx

Tongue in floor of cavity

Palate in roof of cavity

Primary palate

Secondary palate

Teeth

Figure 11.2: Human oral cavity.


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Palates

Primary palate inanamniotes- nasalpassageways empty into oral

cavity Ex: Salamander

Secondary palate of

amniotes- extends topharyngeal cavity

Internal naresFigure 11.3: Oral cavity of

amphibian (a) and mammal (b).


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Teeth On jaws normally

Cheeks in mammals form pocket Acrodont teeth- fish and snakes

Bicuspid- amphibians

Tricuspid- lizards

Pleurodont teeth- snakes

Thecodont teeth-

crocodilians

Figure 11.4- Cross section of jaw.

Figure 11.5- Types of cusps.


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Bird Teeth

Egg caruncle- all egg layers Not actual tooth

Structure epidermal, horny,

keratinized On tip of snout

To penetrate egg shell

Figure 11.6: Egg caruncle of 15 dayold owlet.


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Reptilian Teeth

Egg tooth- lizards and snakes

Actual tooth

Upper jaw

To penetrate egg shell

Figure 11.7: Monitor egg tooth..


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Aglyphous- no modificationsfor venom delivery

Solenoglyphous- retractable

teeth, fangs Proteroglyphous- fangs in front

of mouth

Opisthoglyphous- fangs in backof mouth

Modifications of Snake Teeth

Figure 11.8: Position, cross andlongitudinal sections of aglyphous (1),

opisthoglyphous (2), and solenoglyphous(3) fangs.


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Incisors For cutting

Ex: elephant tusks

Canines For piercing

Ex: walrus tusks

Premolars & Molars To matriculate food

Diastema- space withoutteeth; e.g., no canines

Figure 11.9: Mammalian teethspecializations.

Mammalian Teeth


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Mammalian Teeth

Heterodont dentition

Other varieties

Homodont- all teeth the same Bunodont- all teeth on single plain

Sectorial teethcarnassials; e.g., upper premolar andlower molar in carnivores


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Dental Formula

Figure 11.10: Dental formulae.

Catarrhines and humans have

2-1-2-3=16 x 2 = 32 total teeth

Canines: 3-1-4-2 and 3-1-4-3

If 0 is present, diastema is present


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Tongue

Immobile in jawed fish Fleshy in higher vertebrates

Frog- tongue shoots out and drawsback

Glandular field secretes sticky fluid

Immobile tongue- turtles, crocs,and some birds

Flexible tongue- nectar feedingbats and snakes

Forked tongue of snake

Figure 11.11: Jacobsons organ (sensing

apparatus) of snake and forked tongue.


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Oral Glands

Named based on location Labial- near the lips

Palatal- near palate

Internasal Sublingual- releases venom

Parotid- salivary gland

Submaxillary

Birds have few oral glands

Swifts Figure 11.12: Swift and nest.


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Pharynx

In embryo, exhibits series of lateralpharyngeal pouches

Gives rise to various glands

Slits in pharyngeal region

Figure 11.13: Embryonic pharyngeal

arches and oral development.Figure 11.14: Adult regions of pharynx.


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Pharynx

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


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Esophagus

Muscular tube connecting pharynxand stomach

Can be short

Crop- specialization in birds Outpocketing of esophagus

Used to store food

Pigeons milk

Figure 11.16: Esophagus and

crop of bird.


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Stomach Muscular chamber

Secretes gastric juices

Different lining of stomachs

Esophageal-like epithelia

Glandular epithelia

Ruminant stomach

4 chambers: rumen, reticulum,omasum, abomasum

Human stomach

Cardiac sphincter- esophagus

meets stomach

Mostly lined with gastric epithelium

Figure 11.17: Stomach of mammals withesophageal-like epithelia in gray and glandularepithelia in red.


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Stomach Structure

Greater and lesser curvature Messentaries

Greater omentumattaches along greater curvature

Lesser omentumattaches along lesser curvature

Cecum- increases surface area

2 parts in bird and crocodile stomach

Proventiculus-glandular

Gizzard- grinding mill (gastroliths)


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4-Chambered Stomachs

Figure 11.18: Stomach of calf.

Rumen- food enters Bacterial action

Reticulum- forms a bolus

Omasum- reswallowed grass Salivary action

Abomasum- food worked out

by gastric glands


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Small Intestine

Duodenum- 1stsegment

Bile and pancreatic ducts

Jejunum and Ileumsubdivisions

Figure 11.19: Digestive tract showing

regions of small intestine.


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Brunners Glands- mucous glands in duodenumand jejunum

Peyers Patches- lymphatic nodules in ileum

Crypts of Lieberkhns- intestinal glands at baseof villi

Lacteals- within villiinterior lymphatic vessels

Transport fat molecules to circulatory system

Valve of Kirckring- increases surface area

Small Intestine


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Small Intestine

Figure 11.20: Histology of alimentary canal of a mammalshowing various glands of small intestine.


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Liver

Liver is diverticulum of primitive gut

Liver produces bile

Bile stored in gallbladder

Common bile duct

Ampulla of Vater- terminal portion

Figure 11.22: Development of liver and pancreas.


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Figure 11.1, 11.3, 11.4, 11.5, 11.10, 11.15, 11.16, 11.17, 11.18 & 11.22- Kent, George C. and Robert K.Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.

Figure 11.2- http://www.mouth-cancer-symptoms.com/

Figure 11.6- http://gargravarr.cc.utexas.edu/owl/2002/

Figure 11.7- http://www.proexotics.com/collection_nonPE9.html

Figure 11.8- http://www.kingsnake.com/reptilia-italia/My_HomePage_file/snakesgeneral.htm

Figure 11.9- http://www.okc.cc.ok.us/biologylabs/Documents/zoology/22

Figure 11.11- http://www2.worldbook.com/features/reptiles/html/body_senorg.html

Figure 11.12- http://www.rspb.org.uk/birds/whatyoucando/attracthousemartins/index.aspFigure 11.13- http://people.eku.edu/ritchisong/342notes7.html

Figure 11.14- http://www.cortexity.com:8080/nicksblog/

Figure 11.19- http://www.yoursurgery.com/ProcedureDetails.cfm?BR=1&Proc=49

Figure 11.20- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill,2002.

Figure 11.21- http://www.becomehealthynow.com/popups/lrg_intest.htm

Literature Cited