Digestive System (Oral Cavity to Stomach) Flashcards

1
Q

What is the digestive system comprised of?

A

Oral cavity and alimentary canal

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2
Q

Alimentary canal

A

Includes esophagus, stomach, small and large intestines and several glands
Hollow tube with 4 layers

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3
Q

What are the layers of the alimentary canal?

A
  1. T. mucosa
  2. T. submucosa
  3. T. muscularis
  4. T. Serosa (CT covered by mesothelium) / T. adventitia
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4
Q

What is included in the oral cavity?

A

Lips, palate, teeth, tongue and salivary glands

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5
Q

Epithelium of the lip and cheek (oral cavity)

A

Outer surface: Strat. squamous keratinized with hair
Inner surface: Strat. squamous non-keratinzed (dogs) and keratinized (ruminants and horses)

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6
Q

Hard palate

A

Strat. squamous keratinized (thick in ruminants and forms the dental pad rostrally)
Blended lamina propria and submucosa covering bony tissue

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7
Q

Soft palate

A

Strat. squamous on oral side
Pseudostrat. ciliated on nasal side
Blended lamina propria with lymphatic tissue

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8
Q

What are the functions of the tongue?

A

Mastication, taste, licking and suckling

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9
Q

Mucosa form papillae

A

Filiform (keratinized in horses, ruminants and cats, most numerous, no TB)
Fungiform (mushroom shape)
Foliate (RABBITS, leaf shape)
Circumvallate
Conical and lenticular (lent. only in ruminants, lentil shape)

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10
Q

Mechanical papillae

A

Filiform
Conical
Lenticular

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11
Q

Gustatory

A

Circumvallate (taste buds on lat. side)
Foliate (TB on lat. side)
Fungiform (few TB on dorsal side)

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12
Q

How many planes does the skeletal muscle on the tongue have?

A

3: longitudinal, vertical and transverse

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13
Q

What glands are present on the tongue?

A

Serous/ mucous (VonEdner associated with circumvallate papillae)

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14
Q

Lyssa (tongue)

A

Fatty tissue and muscle in CT capsule
Dog, cat and pig

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15
Q

Horse tongue

A

Dorsal lingual cartilage (hyaline) with CT
(fibroelastic CT and fat)

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16
Q

Ruminants tongue

A

Torus linguae (thickened mucosa on caudal dorsal aspect)
Lenticular papillae

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17
Q

Birds tongue

A

Lingual bone

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18
Q

Taste bud

A

Bell-shaped
Taste cells, supporting cells, and nerve fibers innervating taste cells
4 taste qualities: sweet, salt, bitter and acid

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19
Q

What are the salivary glands?

A

Parotid, mandibular, sublingual, zygomatic (canivores) and molar (cats)

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20
Q

Parotid

A

Serous
Striated ducts

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21
Q

Saliva

A

Contains amylase which starts the carbohydrate digestion in the oral cavity

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22
Q

What do teeth consist of?

A

Soft tissues (pulp cavity and periodontal ligament)
Hard tissues (enamel, dentin and cement)

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23
Q

Enamel

A

Covers the crown
Hardest substance in the body
Acellular and avascular
Have prisms synthesized by ameloblasts (non-regernative)

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24
Q

Dentin

A

Skeleton of the tooth
Living and regenerable
Have dentinal tubules and inter-tubular tissue

25
Q

What are the tubules of dentin composed of?

A

Calcified matrix containing collagen fibers
Synthesized by odontoblasts lining the inner pulp cavity

26
Q

Cementum

A

Covers dentin of the root
Consists of calcifed matrix with collagen fibers synthesized by cementocytes

27
Q

Periodontal ligament

A

Dense CT with no mineral
Fibers penetrate as Sharpey’s fibers on one side and insert to bony alveolus on the other

28
Q

Dental pulp

A

Jelly-like, with fibers
CT cells, BVs, and nerve fibers
Lined by odonoblasts

29
Q

Brachydont

A

Simple
Crown covered by enamel and root by cementum
Teeth in man, carnivores and swine (except canine) and incisors in ruminants

30
Q

Hypsodont

A

Complex
Cement covers root and crown
All teeth in horse and rodents, molars in ruminants, pig canines

31
Q

Tunica mucosa in the esophagus

A

Strat. squamous non-keratinized in man and dog
Strat. squamous keratinized in all other domestic species

32
Q

Submucosa in esophagus

A

Mucous glands
Short cranial segment of horse, cat and ruminants
Cranial half only in pig
Throughout the dog

33
Q

T. Muscularis in esophagus

A

Skeletal throughout dog and ruminants
Skeletal in first two-third, mix of smooth and skeletal in middle , then smooth distally in other species

34
Q

Serosa/adventitia in esophagus

A

Serosal covering in the thoracic and abdominal part
Adventitial in the cervical part

35
Q

How is the stomach classified?

A

Simple, compound monogastric and compound polygastric

36
Q

Simple stomach

A

Rugae (mucosa and submucosa), gastric pits, simple columnar with mucus cells (secrete alkaline)
Glands in lamina propria
TJs

37
Q

Simple stomach in the dog and cat

A

Cardiac (small), fundic and pyloric parts
No cutaneous

38
Q

Simple stomach in the pig

A

Largest cardiac
Small cutaneous part (strat. squamous keratinized)

39
Q

Simple Stomach in the horse

A

Very large cutaneous part
Demarcation with the glandular part (margoplicatus)

40
Q

Compound stomach

A

Rumen, reticulum, omasum: cutaneous part modified to form papillae, fermentation of cellulose to form volatile fatty acids
Abomasum: structurally similar to simple stomach

41
Q

What are the functions of the simple stomach?

A

Continue the digestion of carbohydrate
Add acidic fluid to the food
Transform the food into a chyme
Promote the initial digestion of proteins with enzymes pepsin and secrete hormones

42
Q

What are the 3 regions of the simple stomach?

A

Cardia, fundus, pylorus

43
Q

How long does it take mucous cells to be replaced?

A

every 3-4 days

44
Q

What cell types are present in the simple stomach?

A

Mucous cells
Chief cell (zygomatic)- pepsinogen
Parietal cell
Argentaffin cell (gastrin and secretin)

45
Q

Parietal cell

A

Secretes HCl
Intrinsic factor in human (deficiency–> anemia)
Supports B12 absorption

46
Q

What are the protective mechanisms for the stomach?

A
  1. Alkaline mucous surface coat
  2. Alkaline intestinal fluid
  3. Fully developed junctional complexes
  4. Regeneration of epith.
  5. Vomiting reflex
  6. Immunological defense
47
Q

Fundic glands

A

Predominant gastric glands
Has a isthmus, neck and base
Has all cells

48
Q

Stem cells of the fundic gland

A

Found in isthmus and neck regions
Continuously divide
Replace aging cells of the gastric epith.

49
Q

Parietal cells of the fundic gland

A

Large, eosinophilic, triangular, upper half of fundic gland
Many mitochondria and intracellular canaliculi
Secrete HCL

50
Q

What stimulates HCL production

A

Gastrin and parasympathetic stimulation

51
Q

Chief cells

A

Lower half of fundic gland
Basophilic cytoplasm and zymogen granules
Secretes pepsinogen

52
Q

Argentaffin (enteroendocrine) cells

A

Diffuse endocrine cells (APUD)
Bases of gastric glands
Secretes gastrin, secretin, cholecystokinin

53
Q

Cardiac glands

A

Localized in a narrow zone around and near the esophageal opening into the stomach
Mostly mucous cell types, some parietal
Occupy half in pig

54
Q

What is the function of cardiac glands?

A

Mucus production that protects the esophageal lining from gastric HCL

55
Q

Pyloric glands

A

Almost half of the stomach in dog and cat
Only mucus cells
Deeper gastric pits
Branched and coiled glands

56
Q

What is the function of the pyloric glands?

A

Produce mucus

57
Q

Rumen

A

Cutaneous mucosa forming finger-like conical papillae
Function is to ferment food by microorgs

58
Q

Reticulum

A

Cutaneous mucosa, honeycomb structure
Function is to break down food

59
Q

Omasum

A

Cutaneous mucosa and submucosa form primary and secondary folds
Function is to breakdown food