Chapter 13: Digestive System Flashcards Preview

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Flashcards in Chapter 13: Digestive System Deck (49):
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Teeth

Evolved from dermal scales
About 400 mya
Embryology: interaction of epidermis and dermis

1

Tooth Anatomy

Crown
Root
Enamel
Dentine
Pulp cavity
Cement

2

Tooth attachment

1. Collagen fibers to jaw (sharks)
2. Pleurodont = medial margin of jawbone (on side, amphibs)
3. Acrodont = summit of jawbone (reptiles)
4. Thecodont = teeth embedded in jawbone -> more stable (mammals)
Thecodont means "deep socket tooth"

3

Diphydont

2 sets of teeth
Mammals (baby/milk/deciduous then adult/permanent teeth)

4

Polyphydont

Many sets of teeth
Sharks, some bony fish

5

Homodont

Same shape
Not as good for chewing

6

Heterodont

More than a single tooth shape
Ex: incisors, canines, molars for specialized hunting and feeding

7

Edentate

Do not have teeth
Ant-eaters, birds, turtles

8

Mammal teeth terms

Incisors= grab, cut
Canines= tear
Premolars/molars (cheek teeth) = chew on occlusal surface
Prisms (type 1 of occlusal surface)= ridges
Cusps (type 2)= bumps, grooves
Carnassials (type 3)= sheer past one another for cutting
Diastema= gap (rodents, rabbits, deer, horses)

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Agnathan teeth

No teeth (bumps that are tooth-like)
Ancestral: filter-feeder
Small mouth, no jaw
Larger pharynx

10

Placoderm teeth

No teeth
Shearing plates - large

11

Chondrichthyes teeth

Numerous teeth, homodont
Non-movable tongue -cartilaginous
Fibrous attachment with collagen -loose
Constantly growing new teeth (and losing them ->fossilize)

12

Osteichthyes teeth

Up to 10,000 teeth
Jaw, roof of mouth, tongue, gills, pharynx
Homodont
Acrodont
Non-movable tongue
Large oral cavity

13

Amphibian teeth

Few, small, homodont
Pleurodont attachment
Movable tongue*
Old: Labyrinthodonts (bc of shape)

14

Reptilian teeth

Mostly homodont
Thecodont attachment
Some synapsids heterodont
Turtles edentate

15

Ave teeth

Edentate, mostly immobile tongue
Some primitive ones had teeth

16

Mammalian teeth

Diverse
Heterodont
Homodont

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Oral glands in Tetrapods

Food lubrication (no longer feed in water)
Modifications:
1) poison; lizards, snakes, shrews
2) anticoagulant; vampire bat
3) salt excretion; "nasal glands" marine + desert birds and reptiles
*exocrine glands

18

Alimentary canal: functions

Receive food
Store food
Reduce food physically and chemically (break down of food)
Absorb nutrients
Eliminate digestive waste *not excretion

19

Storage areas

Stomach
Crop (birds) -> intended
-> first chamber

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Physical reduction

1) chewing or grinding
-teeth
-stomach with gravel = alligators, birds
2) moistening
-mouth, stomach, intestine
3) churning and mixing
-stomach
4) emulsification of fats
-liver produces bile

21

Chemical reduction

-stomach and small intestine *
-enzymes (lining and pancreas)

22

Fish stomachs

Stomach "N" or "J" shaped

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Amphibian stomach

Simple stomach

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Reptiles stomach

Simple stomach
Crocs, very muscular

25

Birds stomach

Crop-> storage
Stomach
1. Proventriculus
-Contains enzymes
2. Ventriculus or gizzard
-grinding, gravel

26

Mammals stomach

1. Sac-like
-humans, most carnivores, rodents
2. Complex, multi-chambered
-herbivores
-ruminants -> rumen= fermentation, symbionts, anaerobic
-many marsupials

27

Rumen

Ex: cows
Full up stomach as fast as they can with grass > let it sit > regurgitate > chew + swallow again until they need more. (Process it over a long period of time)
Called remasticate

28

Intestines

1. Enzymes for breakdown
-lining
-pancreas
2. Surface area for absorption
-long
-folded
-villi (entire lining)
-microvilli (finger-like projections on each cell

29

Fish intestines

Just "intestine"

30

Tetrapods intestines

"Small" and "large"
Vitamin B synthesis in large
Cecum = blind sac between small and large
Large: in herbivores, symbionts
Small: duodenum -> jejunum -> ileum
*loops of intestine held in by mesentary to prevent everything getting tangled up

31

Agnatha intestines

*eat blood and suck fluids -> no need for complexity
-straight intestine, gentle spiral

32

Cartilage fish intestine

Spiral valve = surface area

33

Bony fish intestine

Long, coiled

34

Amphibians intestine

Tadpoles; long, coiled (eat algae, takes awhile to digest - herbivores)
-adults; shorter (eat more meat, carnivores)

35

Reptiles intestines

Snakes; straight
Others; some coiling

36

Birds intestines

Long
2 ceca
Bursa of Fabricius -> out pocketing near end
-in young birds
-antibody formation
*homologous to appendix

37

Mammals intestines

Small intestine:
-duodenum >enzymes
-jejunum
-ileum >most distal, absorption
Cecum:
-large in hindgut fermenters (herbivores: horse, rabbit)
Con or large intestine:

38

Liver

Large, vascular
Hepatic ducts -> drain bile from liver
Cystic duct to gall bladder -> for storage then sent to....
Common bile duct (nuclei around ring)

39

Some liver functions

Produce bile for emulsifying fat and neutralizing acid
Vitamin manufacture
Detoxification
Yolk production
Storage for carbs and fat
Deamination of protein, interconversions (carbs -> lipids or proteins -> carbs)

40

Gall bladder

Stores bile
Small sac
Important in episodic feeders (eat in episodes: 1 big meal and then nothing for a while)
Absent in some herbivores (deer, horses)

41

Pancreas

Gland near duodenum and stomach
-exocrine (97%)
•ducts (empty into duodenum - converge with common bile duct)
•secrete digestive enzymes
-endocrine
•hormones for sugar metabolism
>insulin - decrease blood glucose
>glucagon - increase blood glucose

42

Lining of body cavities

Colonic cavity
Lining from hypomere of mesoderm
Outside wall = parietal peritoneum/serosa
Inner layer on organs = visceral peritoneum
Dorsal mesentery
Omentum (fat storage) -sheet of mesentary that connects organ to organ
Ventral mesentery

*all of these prevent torsion and hold in place but still allow movement*

43

Mesenteries

Keep organs in place -> prevent torsion
Ventral mesentery often degenerates
Ex: falciform ligament

44

Coelomic divisions

Pericardial cavity = heart
Peritoneal cavity = abdominal organs
Pleuroperitoneal cavity = lungs + abdominal organs (shark, fish, amphibians)
Pleural cavities = lung

45

Hagfish coelom

Partial separation of pericardial and abdominal cavities

46

Lamprey, fish, amphibians Coelom

Full separation of pericardial and peritoneal cavities

47

Reptiles and birds Coelom

Pericardial, 2 pleural (thoracic)
Peritoneal

48

Mammals Coelom

Pericardial, 2 pleural, fully muscular diaphragm
Peritoneal