DIGESTIVE SYSTEM 1 Flashcards

1
Q

what is an alimentary tract?

A

A muscular tube, lined internally by an epithelium

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2
Q

what epithelium lines the alimentary tract?

A

Epithelial type varies along length, depending upon function

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3
Q

what are the structures of the oral cavity?

A

Teeth and periodontium (supporting tissue)
Tongue
Salivary glands

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4
Q

what is the major functions of the oral cavity?

A

Ingestion + mechanical fragmentation of food

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5
Q

what is the major histology of the oral cavity?

A

Lining of stratified squamous epithelium

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6
Q

what is the structure of the tongue?

A

highly muscularised

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7
Q

what is the function of the tongue?

A

Manipulates food for mastication

Taste

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8
Q

what is the surface of the tongue covered by?

A

lingual papillae

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9
Q

what does the lingual papillae include?

A

Filiform (most numerous)
Fungiform
Circumvallate
Foliate

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10
Q

what are the structures of the transport passages?

A

Pharynx
Oesophagus
Anal canal

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11
Q

what is the structure of the transport passages?

A

Simple muscular transport tubes
Lined with stratified squamous epithelium
Some mucous glands for lubrication

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12
Q

what are the 3 layers of the oesophagus?

A

mucosa
muscular externa
adventitia

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13
Q

what is the structure of the mucosa of the oesophagus?

A
Stratified squamous epithelium (above diaphragm)
Columnar epithelium (below diaphragm)
Well defined lamina propria + muscularis mucosae
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14
Q

what is the structure of the muscular externa of the oesophagus?

A
Striated muscle (upper third)
Striated and smooth muscle (central section)
Smooth muscle (lower third)
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15
Q

what is the structure of the adventitia of the oesophagus?

A

Layer of loose connective tissue

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16
Q

what are the structure so the digestive tract?

A
Stomach
Small intestine (Duodenum, jejunum, ileum)
Large intestine (Caecum, appendix, colon, rectum)
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17
Q

what is the histology of the tract?

A

Mucosa
Many epithelial types
Efficiency of absorption
Formation of complex glands

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18
Q

what is the mucosa of the tract?

A

Inner layer surrounding tract – most variable component

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19
Q

what are the epithelial types of the tract?

A

Absorptive

Secretory

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20
Q

what is the efficiency of absorption of the tract?

A

Intrusions/folding of epithelium Villi/plicae

Inversions

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21
Q

what are the 4 layers of the tract?

A

mucosa
submucosa
muscular externa
serosa

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22
Q

what does the mucosa contain?

A

epithelium

lamina propria

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23
Q

what is the epithelium of the mucosa?

A

Mainly columnar epithelial cells

Glandular secretions moisten surface

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24
Q

what is the lamina propria?

A

Composed of loose CT
Contains small blood vessels, lymphatics, nerve fibres
Other specialist cells e.g. macrophages & lymphocytes

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25
Q

what is the function of the submucosa?

A

Separates mucosa from underlying muscle layers

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26
Q

what does the submucosa contain?

A

More neural tissue
Submucosal plexus (Meissner’s plexus)
Regulates contractions + glandular secretions

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27
Q

what does the muscular externa contain?

A

smooth muscle
Layers allow peristaltic contractions
2nd nerve plexus located between muscular layers - Myenteric (Auerbach’s) plexus

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28
Q

what are the 2 layers of smooth muscle in the muscularis externa?

A

Inner: circular layer
Outer: longitudinal

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29
Q

how do the layers allow peristaltic contractions?

A

Circular layer is actually a compact spiral

Longitudinal layer is actually an elongated helix

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30
Q

what is the serosa+adventitia layer?

A

Covers muscularis

Delimits alimentary canal

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31
Q

what is the serosa?

A

When outermost layer lies adjacent to peritoneal cavity

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32
Q

what is the adventitia?

A

When connected to surrounding tissue

33
Q

what is the serosa also known as?

A

visceral peritoneum

34
Q

what is the function of the serosa?

A

CT with simple squamous epithelium

Lines majority of small and large intestine

35
Q

where doesn’t the serosa line?

A

part of duodenum + an area of the colon

36
Q

where is no serosa found?

A

in oral cavity/ pharynx/ oesophagus/ rectus

37
Q

what is the mesothelium?

A

the epithelial component of the serosa

38
Q

what is the mesentary?

A

double layer of visceral peritoneum

39
Q

what is the adventitia connected to and made of?

A

layer is connected to surrounding tissues

made of fibrous CT

40
Q

what is the stomach?

A

Digestive organ + reservoir

41
Q

what are the 4 anatomical regions of the stomach?

A

Cardia
Fundus
Corpus (body)
Pylorus

42
Q

what does the stomach contain?

A

mucosa

muscularis externa

43
Q

what is the mucosa of the stomach?

A

Muscularis mucosae - circular and longitudinal muscle fibres

44
Q

what are the 3 layers of the muscularis external of the stomach?

A

oblique, circular, longitudinal

45
Q

what is the structure of the gastric mucosa of the stomach?

A

Columnar epithelium
Rugae (gastric folds)
Gastric pits

46
Q

what is the rugae of the stomach?

A

Apparent when stomach is empty

Disappear when stomach is distended (full)

47
Q

what are the gastric pits of the stomach?

A

Shallow surface depressions on surface

48
Q

what are the tubular gastric glands of the stomach?

A

Open into gastric pits

Occupy entire mucosa

49
Q

what is the function of the tubular gastric glands of the stomach?

A

Contain mucus producing cells

Mucus forms secretory sheath to protect against acid

50
Q

what are the gastric glands (at cardia)?

A

Heavily branched

Mucus-producing glands

51
Q

what are the principal glands(corpus-fundic) of the stomach?

A

Mucus neck cells

52
Q

what are the chief cells in the principal glands of the stomach?

A

(zymogenic) – produces enzymes

53
Q

what are the parietal cells in the principal glands of the stomach?

A

(oxyntic) – acid secreting

54
Q

what are the enter-endocrine cells in the principal glands of the stomach?

A

stimulate secretion in other cells

55
Q

what are the pyloric glands of the stomach?

A

More coiled than principal glands
Endocrine cells more frequent
No chief cells

56
Q

what is the small intestine?

A

Most important digestive + absorptive functions occur here

57
Q

what are the 3 sub-divisions of the small intestine?

A

Duodenum
Jejunum
Ileum

58
Q

what does the mucosa of the small intestine contain?

A
plicae 
intestinal villi-entire intestinal mucosa 
microvilli on enterocytes 
tubular glands
goblet cells
muscularis mucosae
59
Q

what is the function of the plicae of the small intestine?

A

Increase SA
Permanent structures
Absent from start of duodenum

60
Q

what is the function of the intestinal villi of the small intestine?

A

Increase SA

Main cell type: enterocytes

61
Q

what is the function of enterocytes?

A

have absorptive function

62
Q

what is the function of themicrovilli on enterocytes of the small intestine?

A

increase SA

63
Q

what does increasing the SA in the small intestine do?

A

improve efficiency of absorption

64
Q

what is the function of Tubular glands (Crypts of Lieberkühn) in the small intestine?

A

from base of villi, through lamina propria to muscularis mucosae
Secrete “intestinal juice”
Paneth cells at base of crypt

65
Q

what is the function of panted cells of the small intestine?

A

secretion + control of infection

66
Q

what is the function of goblet cells in the small intestine?

A

secrete mucous

67
Q

what is the muscularis mucosae in the small intestine?

A

Two layers + extend into villi

68
Q

how does the regeneration of intestinal epithelia occur?

A

Epithelial cell turnover time: 1% per hour
Undifferentiated stem cells at base of crypt
Stem cells divide and ‘move up’ through crypt + villi

69
Q

what does the submucosa of the small intestine contain?

A

glands only in the duodenum (Brunner’s glands)

70
Q

what is the function of Brunner’s glands?

A

Secrete mucus to protect duodenal lumen

71
Q

what does the muscularis externa of the small intestine contain?

A

Circular + longitudinal layers

Covered by serosa

72
Q

what is the large intestine?

A

Frames small intestine

Reabsorption of water and inorganic salts

73
Q

what are the 3 section of the large intestine?

A

Caecum (inc. appendix)
Colon (ascending, transverse, descending, sigmoid)
Rectum (inc. anal canal)

74
Q

what does the mucosa of the large intestine contain?

A
smooth surface 
Crypts of Lieberkühn
(longer than in SI)
goblet cells (more numerous than in SI)
Few endocrine cells
Thin lamina propria
Muscularis mucosa (2 layers)
75
Q

what is the serosa of the large intestine?

A

Forms small pouches filled with adipose along large intestine

76
Q

what is the muscularis externa of the large intestine?

A

Different appearance from SI

Longitudinal muscle layer forms 3 flattened strands (Taeniae coli)

77
Q

what is the Taenia coli?

A

t

78
Q

what is the Hausfrau coli?

A

sacculations of the colon