week 21 lower GI anatomy Flashcards

1
Q

where does the small intestine run to and from

A

runs from pyloric sphincter of the stomach to the caecum of the large intestine

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2
Q

how long is the small intestine

A

6-7 metres long

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3
Q

what are the three regions of the small intestine

A

duodenum
jejenum
ileum

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4
Q

what is the smallest section of the small intestine

A

duodenum

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5
Q

the duodenum is continuous with what

A

stomach

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6
Q

the ileum is continuous with what organ

A

large intestine

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7
Q

where does the duodenum receive chyme from

A

stomach via pyloric sphincter

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8
Q

what 4 substances does the duodenum receive from the pancreas

A

sodium bicarbonate
amylase
lipase
precursors of proteolytic enzymes

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9
Q

what does the duodenum receive from the gall bladder

A

bile acids

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10
Q

in what part of the small intestine has the most absorptive properties

A

duodenum

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11
Q

what 3 (elements) does the duodenum absorb

A

calcium
iron
folate

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12
Q

in what part of the small intestine has the greatest absorptive property for bile acid

A

ileum

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13
Q

what is the only place in the small intestine that absorbs cobalamin

A

ileum

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14
Q

the jejunum specialises in the absorption of what

A

fat
protein
carbohydrates

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15
Q

what is the epithelial structure of the jejunum

A

simple columnar epithelium

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16
Q

what does the ileum specialise in absorption of

A

B12 and bile acid

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17
Q

the basic simple columnar epithelial layers are the same as other sites in the GI tract but there are additional modifications in the small intestine to maximise what

A

surface area

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18
Q

what are plicae circulares

A

circular folds of the mucosa and submucosa

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19
Q

what are plicae circulares most prominent

A

distal duodenum and jejunum

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20
Q

the number of plicae circulares decrease in size and number as…

A

you move along the intestine

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21
Q

when are there no more plicae circulares

A

proximal area of the ileum

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22
Q

what are villi

A

finer like projections of epithelium covered lamina propria which protrude into the lumen of the small intestine

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23
Q

what are the functions of the microvilli

A

projections of the apical surface of the epithelial cells which further increase surface area

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24
Q

how much do micro villi increase absorption

A

20-30 x

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25
Q

what is the “fuzzy coat” on the micro villi made out of

A

glycoprotein

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26
Q

what are crypts of Lieberkühn

A

invaginations of the epithelial surface to meet the underlying lamina propria

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27
Q

what do the cell populations in the crypts of lieberkuhn essential for

A

aiding digestion, absorption, and protective features

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28
Q

what is the epithelial structure of crypts of lieberkuhn

A

columnar epithelial

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29
Q

what are the cells in the crypts of lieberkuhn

A

goblet cells
intermediate cells
M cells
paneth cells
enteroendocrine cells

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30
Q

what is the most populous cell type in the crypts of lieberkuhns (small intestinal epithelium)

A

enterocytes

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31
Q

absorptive role in the small intestine is facilitated by what

A

apical and basolateral transporters, enzymes

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32
Q

what are the transporters that help facilitate absorptive roles in the small intestine

A

SGLT1 and GLUT 5 (apical membrane)
Na+/K+ATPase GLUT2 GLUT5 (basolateral membrane)

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33
Q

what are the roles of regenrative cells in crypts of lieberkuhns

A

stem cells which can proliferate and can replace any cell type of the crypt epithelium

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34
Q

what are the roles of intermediate cells in the crypts of intermediate cells

A

they are the “babies” of regenerative cells
and soon specialise to become any cell in the GI

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35
Q

what are the roles of paneth cells

A

secretory function

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36
Q

what do the paneth cell secrete

A

lysozyme
TNFalpha

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37
Q

paneth cells secrete lysozyme, what is its function

A

antimicrobial product (protectiveP pathogenic material

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38
Q

what do enteroendocrine cells secrete

A

GLP1
Cholecystokinin (CCK)
glucose dependant insulontropic polypeptide (GIP)

39
Q

what does GIP respond to

A

secretagogues

40
Q

what can GIP open

A

enteroendocrine cells

41
Q

what can GIP increase/decrease

A

motility of products released from accessory glands - pancreas

42
Q

in the mucosa of the small intestine, the layers extend into the villi shortening the villi rhythmically during what

A

digestion

43
Q

the serosa is not present where

A

distal 2/3rds of the duodenum

44
Q

what is a structural difference of the villi in the duodenum

A

shorter and stumpier

45
Q

what glands are present in the duodenum

A

brunner glands (submucosa)

46
Q

what is the tole of brunner glands

A

produce mucous, bicarbonate rich fluid and human epidermal growth factor

47
Q

what is the role of bicarbonate

A

acts as a buffer to stomach acid

48
Q

brunner glands can be site for what (bad) thing

A

brunner-gland adenomas

49
Q

what can be said about the number of villi in the jejunum compared to the duodenum

A

sparser number of villi

50
Q

what are the more of in the jejunum that the duodenum

A

goblet cells (synthesise and secrete mucous)

51
Q

in a histological slide, how can you tell the difference between an artery and a vein

A

arteries are thicker and rounder

52
Q

in the ileum, what can be described as “clustered lymphatic tissue in the lamina propria”

A

peyer’s patches

53
Q

wjat do peyers patches do

A

help remove foreign bodies

54
Q

what is there least of in the ileum compared to the jejunum and duodenum

A

villi

55
Q

why is there fewer instances of cancer metastasis in the large intestine

A

there is less well developed lymphatic system vasulature

56
Q

how is peristalsis achieved

A

activation of smooth muscle layers in the musclaris externa

57
Q

in the muscularis externa, how does the inner circular layer aid in peristalsis

A

pinching motions

58
Q

in the muscularis externa, how does the outer longitudinal layer aid in peristalsis

A

shortening of the length of the small intestine/regions

59
Q

where is the myenteric plexus

A

exists between the layers of muscle

60
Q

muscle layers can depolarise and stimulate the contraction without the myenteric plexus in

A

peristalsis

61
Q

innervation of peristalsis is delivered by what

A

myenteric plexus

62
Q

adjacent smooth muscle cells are coupled by gap junctions - _____ _____ flow from cell-cell

A

electrical currents

63
Q

spontaneous activity across coupled cells is driven by what

A

pacemaker cells

64
Q

spontaneous activity across coupled cells is driven by specialised pacemaker cells and is modulated by what (2)

A

intrinsic (enteric - myenteric plexus) and extrinsic (autonomic nerves)
numerous hormones (motilin increases) (glucagon decreases)

65
Q

what are slow waves driven by

A

interstitial cells of Cajal

66
Q

ICCs form what with eachother

A

gap junctions

67
Q

ICCs form gap junctions with eachother and smooth muscle cells _____

A

electrically coupling them

68
Q

slow waves in the ICC drives slow waves in the

A

smooth muscles cells coupled to them

69
Q

why dont depolarising slow waves necessarily result in smooth muscle contraction

A

contraction in the small intestine occurs only if the slow wave amplitude is sufficient to reach a threshold to trigger smooth cell calcium action potentials

70
Q

what are the ions involved in smooth muscle contraction by slow waves

A

calcium

71
Q

what is needed for the contraction of smooth muscle

A

slow wave to reach threshold to trigger calcium release

72
Q

in slow waves what is force related to

A

number of action potentials discharged

73
Q

what are the 4 regions of the large intestine

A

caecum
colon
rectum
anus

74
Q

what are the 4 regions in the colon

A

ascending
transverse
descending
sigmoid

75
Q

how long is the large intestine

A

1 1/2 metres

76
Q

what occurs in the large intestine

A

site of fermentation, storge, and water reabsorption

77
Q

functions of the large intestine
recovery of ______
absorption of ____-____ ______ ____
fermentation
storage
defecation

A

water
short chain fatty acids

78
Q

what is the epithelial structure in the colon

A

simple columnar epithelium

79
Q

what is there 0 of in the colin

A

villi

80
Q

organisation of what epithelial layer is different in the colon

A

muscularis externa

81
Q

the lamina propria is well populated with what cells

A

immune cells

82
Q

the mucosa (muscularis externa) contributes to what system

A

gut-associated lymphoid system (GALT)

83
Q

in the large intestine - the muscularis externa exhibits what structure

A

ribbons of outerlongitudinal layer of muscularis externa = taeniae coli

84
Q

in the large intestine (serosa) fat filled pouches are what

A

appendices epiploicae

85
Q

what is the epithelial structure of the large intestine (anus and rectum)

A

simple comulnar

86
Q

what crypts are deeper in the anus and rectum

A

crypts of lieberkuhns

87
Q

in the anal canal - the simple columnar epithelium changes to what

A

simple cuboidal epithelium -> stratisfied squamous and then stratified squamous keratinised

88
Q

submucosa of the anal canal contains what

A

venous plexi (internal and external hemorrhoidal plexi)

89
Q

what is the muscle composition of the internal anal sphincter

A

smooth muscle - involuntary

90
Q

what is the muscle composition of the external anal sphincter

A

skeletal muscle - voluntary

91
Q

the exposure of the GI epithelium to viruses/parasites/toxins results in what

A

peristatic rush and release of copious volumes of fluid
diarrhoea

92
Q

what is crohns disease

A

inflammatory bowel disease (inflammation affcets the full thickness of the GI tract

93
Q

symptoms of crohns disease

A

abdominal pain, weight loss, malabsorption, rectal bleeding

94
Q

what cancer are you at greater risk of if you have crohns disease

A

colorectal cancer