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Flashcards in GI Session 1 Deck (132):
1

What are the three narrowings of the oesophagus?

Cricopharyngeal sphincter
Broncho-aortic constriction
Inferior oesophageal sphincter

2

Is the inferior oesophageal sphincter a true sphincter?

No, physiological caused by diaphragmatic constriction and angle made with junction of stomach

3

How far is oesophagsatric mucosal junction from the incisors?

40 cm

4

What is visible on endoscopy of the oesophagus at the oesophagogastric mucosal junction?

Pale pink squamous epithelium --> dark red gastric epithelium

5

What is hiatus hernia?

Where the cardia and fundus of the stomach push through the oesophageal opening in the diaphragm

6

What is Barrett's oesophagus?

Chronic acid exposure cause metaphase of squamous epithelium to gastric columnar epithelium

7

What are the five regions of the stomach?

Cardia
Fundus
Body
Pyloric antrum
Pylorus

8

Where is gastric ulceration most commonly seen in the the stomach?

At the lesser curvature

9

Which part of the stomach is removed in sleeve gastrectomy in bariatric surgery?

Greater curvature

10

Where do peptic ulcers which bleed slower than those in the duodenum develop?

Pyloric canal

11

Describe the nervous control of the oesophagus.

Superior 1/3 voluntary
Inferior 2/3 autonomic

12

What gives arterial supply to the superior 2/3 of the oesophagus?

Systemic arteries: inferior thyroid and aortic branches

13

What gives venous drainage to the superior 2/3 of the oesophagus?

Systemic veins: inferior thyroid and Azygos branches

14

What gives arterial and venous drainage to the inferior 1/3 of the oesophagus?

Portal system: L gastric branch of coeliac trunk, L inferior phrenic artery, drains into L gastric vein

15

What causes oesophageal varices?

In portal hypertension blood can't pass through portal hepatic vein so there is a reversal of blood flow through porto-systemic anastomoses --> oesophageal submucosal veins dilate with increased flow

16

What controls entry of stomach contents into the duodenum?

Pyloric sphincter at the end of the pyloric canal formed by muscular thickening

17

What are rugae in the stomach?

Longitudinal gastric folds that allow for expansion of the stomach

18

What overlaps the first portion of the duodenum?

Liver and gallbladder

19

Describe the position of the second part of the duodenum.

Descends retroperitoneal around the head of the pancreas

20

What is the significance of the embryological origin of the second part of the duodenum?

Marks transition from embryonic foregut to midgut therefore receives blood supply from coeliac trunk and SMA

21

Describe the passage of the third part of the duodenum.

Runs transversely at L2/3 level crossing the aorta below SMA origin

22

Describe the position of the fourth part of the duodenum.

Retroperitoneal and ascends to left of midline where it turns to form the duodenojejunal flexure

23

What happens to the duodenum as it forms the duodenojejunal flexure?

Becomes intraperitoneal and has a mesentery

24

Why is the first part of the duodenum most likely to ulcer?

Lack of mucus and acidity of contents which is yet to be neutralised by addition of HCO3-

25

What happens if a duodenal ulcer in the first part of the duodenum erodes anteriorly or posteriorly?

Anteriorly --> peritonitis
Posteriorly --> perforates gastroduodenal artery causing massive haemorrhage or erodes into pancreas causing severe pain in lumbar region

26

What an lead to gallstone ileus?

Erosion of a gallstone causing a choledocoduodenal fistula which the stone can then pass through

27

What supports the duodenojejunal flexure?

Ligament of Treitz

28

What signifies the opening of the main pancreatic duct into the duodenum?

Major duodenal papilla

29

What controls release of contents from the pancreatic duct into the duodenum?

Sphincter of Oddi

30

What does ulceration in the second part of the duodenum suggest?

Pancreatic disease
Zollinger-Ellison syndrome

31

What is Zollinger-Ellison syndrome?

Gastrin-secreting tumour stimulates parietal cells to maximal activity

32

What can form in the third part of the duodenum if either the aorta or duodenum is diseased?

Aorto-duodenal fistula

33

What is seen following dramatic weight loss in the third part of the duodenum?

SMA syndrome where aorta and SMA press on the third part of the duodenum causing partial/complete obstruction

34

What an happen in the duodenum in deceleration injury?

Traction injury caused by ligament of Treitx pulling of duodenojejunal flexure and causing subsequent perforation

35

Where does the ligament of Treitz descend from?

Right crus of diaphragm

36

What does contraction of the ligament of Treitz aid?

Persistalsis

37

Describe the passage of the common bile duct.

Passes behind duodenum to run in a groove within the pancreas entering the duodenum at the Ampulla of Vater

38

Where can the Pringle manoeuvre to control hepatic haemorrhage be applied?

Along the free edge of the lesser omentum where the common bile duct, portal vein and artery run

39

What are the components of the biliary tree?

Intrahepatic ducts --> R and L hepatic ducts --> common hepatic duct --> +cystic duct from gallbladder --> common bile duct

40

What do S/S of jaundice, dark urine and pales stool indicate?

Blockage of the common bile duct causing disruption of entero-hepatic bile salt

41

What is painless obstructive jaundice commonly secondary to?

Tumour: carcinoma of head of pancreas, cholangiocarcinoma, adenocarcinoma of duodenum, liver tumour causing extrinsic pressure

42

What does painful obstructive jaundice suggest?

Gallstone disease

43

What attaches the small bowel to the posterior abdominal wall?

15 cm long mesentery from DJ flexure to R sacroiliac joint

44

Why does the jejunum have a thicker wall than the ileum?

More, larger and taller pliae circulares

45

Why is the jejunum deeper red than the ileum?

Greater blood supply

46

What atrophies in coeliac disease?

Deep crypts with tall villi of jejunal wall

47

What can cause luminal obstruction of the ileum in lymphoma?

Enlargement of the abundant Peyer's patches

48

What are Peyer's patches which are found in the ileum?

Aggregates of lymphoid tissue

49

What is Meckel's diverticulum?

Embryological remnant in distal ileum with gastric mucosa that secretes acid

50

What is the rule of 2s that Meckel's diverticulum follows?

Seen in 2% of the population
2 inches long
Presents at 2 y.o.
2 ft from iliocaecal valve

51

Which quadrants is the jejunum mainly located in?

L and R upper quadrants

52

Which quadrants is the ileum mainly situated in?

R and L lower quadrants

53

Is the colon longer in males or females?

Females

54

How long is the colon typically?

100-180 cm

55

What forms the taenia coli?

3 longitudinal bands of muscle along the length of the colon

56

Where do the taeni coli converge and what is the result of this?

In appendix which makes its lumen look triangular

57

What forms saculations in the colon?

Longitudinal bands of muscle being shorter than the colon

58

What prevents back flow of colonic contents during persistalsis?

Iliocaecal valve

59

Why is the rectum lumen circular?

Due to thick circular muscle needed to for formed stool passage

60

What breaks the appearance of the circular lumen of the rectum?

Haustral folds

61

What is the dentate/pectineal line formed by?

Valves of Ball from vertical columns of Morgagni

62

What is the significance of the pectineal line?

Watershed for supply and drainage

63

What supplies and drains the rectum above the pectineal line?

IMA
Visceral pelvic splanchnic nerves
IMV
Mesenteric nodes

64

What supplies and drains the rectum below the dentate line?

Internal iliac artery
Inferior rental nerve
Internal iliac vein
Iliac and inguinal nodes

65

How does pain sensed above and below the dentate line compare?

Above is dull and poorly located, below is sharp and well localised

66

Describe the position of the transverse colon with relation to surface markings.

Lies at umbilicus but may hang down into pelvis, esp in women

67

What forms the iliocaecal valve?

Oblique entrance a partial invagination of the ileum

68

How long is the ascending colon?

12-20 cm

69

How long is the transverse colon?

45 cm

70

How long is the descending colon?

22-30 cm

71

Where is the appendix found?

3 cm below the iliocaecal valve

72

Where does the caecum lie?

R iliac fossa

73

What are the fat filled peritoneal tags on the colon called?

Appendices epiploicae

74

How long is the sigmoid colon?

37 cm usually but can be up to 70 cm

75

How do colonic tumours in the caecum present?

Mass
Change in bowel habit
Decreed iron levels --> anaemia
Pain

76

What causes the caecum to dilate or perforate in large bowel obstruction?

Iliocaecal valve preventing back flow of air and colonic contents which cannot pass distally

77

Where does the rectum extend from and to?

S3 --> anal canal

78

Where is the most common location of colonic diverticulum?

Arterial entry point of sigmoid colon

79

Are colonic diverticuli in the sigmoid colon true diverticuli?

No because they do not involve the entire thickness of wall of parent organ

80

What can occur as a result of the length and loose mesenteric attachment of the sigmoid colon?

Sigmoid volvulus

81

What are the S/S of sigmoid volvulus the same as?

Large bowel obstruction with clack cal radiological appearance

82

How is sigmoid volvulus treated?

Flexible sigmoidoscopy

83

Where do 50% of colon cancers arise?

Rectum

84

Are tumours the same above and below the dentate line and why?

No, above has hindgut origin so is columnar epithelium and below is ectoderm so stratified squamous epithelium

85

What causes haemorrhoids?

Varices in portal hypertension due to porto-systemic anastomoses in rectum

86

How do haemorrhoids above and below the pectineal line compare?

Above are relatively painless so can be injected/banded
Below are very painful

87

How long is the oesophagus?

25 cm

88

What forms the alimentary canal?

Mouth
Tongue
Pharynx
Oesophagus
Stomach
Small intestine
Colon
Appendix
Rectum
Anus

89

What are the accessory organs to the alimentary canal?

Salivary glands
Liver
Gallbladder
Pancreas

90

What forms the mucosa of the gut wall?

Epithelium, LP with aggregations of lymphocytes in Peyer's patches, muscularis mucosae

91

What forms the submucosa of the gut wall?

Layer of CT with glands, arteries, veins and nerves which are particularly on the outer edge near the muscle

92

What forms the muscularis externae of the gut wall?

Outer longitudinal and inner circular layers of muscle which spiral down the gut to create peristaltic waves

93

What forms the serosa of the gut wall?

CT covered by simple squamous epithelium which surrounds most but not all of the gut

94

What does the serosa of the gut wall form?

Mesentery which contains arteries, veins and nerves

95

What are the layers of the gut wall from innermost to outermost?

Mucosa
Submucosa
Muscularis externae
Serosa

96

What are the major functions of the GI tract?

Movement of food
Absorb nutrients
Mechanically disrupt food
Port of food entry
Eliminate residual waste material
Temporarily store food
Chemically digest food
Sterility

97

Where is movement of food most rapid in the GI tract?

Oesophagus and rectum

98

What are the major steps in the digestion of food?

Physical and chemical disruption --> sterile, neutral pH, isotonic solution --> absorption

99

What causes physical and chemical disruption of food in the mouth?

Physical: teeth, tongue, muscles of mastication
Chemical: salivary amylase and lipase

100

What protects teeth in the mouth?

High calcium concentration of saliva

101

How much saliva is added to ingested food in the mouth?

1.5 l

102

What provides innervation to the oesophagus?

Submucosal and myenteric plexuses

103

Where is the myenteric plexus located?

Between circular and longitudinal layers of muscle in the oesophagus

104

What gives paracrine control of motility and secretion in the GI tract?

Histamine controls gastric acid
Vasoactive substances control gastric blood flow

105

Why is fluid balance in the GI tract delicate?

Large quantities that are vary variable are involved

106

What gives neural control of motility and secretion in the GI tract?

Somatic: mouth, 1/3 oesophagus, last sphincter of anus
Autonomic: everything else via submucosal and myenteric plexuses with lots of neurotransmitters

107

What gives endocrine control of motility and secretion in the GI tract?

Secretin, gastrin and CKK control gastric acid, alkali and enzyme secretion

108

How much fluid is added to ingested food by the stomach?

2.5 l of gastric secretions

109

Why does the stomach act as a necessary food store?

We eat faster than we can digest

110

What is the purpose of receptive relaxation in the stomach?

So pressure doesn't rise as it stretches from 50 ml to 4 l

111

How does the stomach physically disrupt ingested food?

Contracts rhythmically to move dynamic rugae

112

What cells are found in the stomach and what do they secrete?

Chief - enzymes
Parietal - acid and intrinsic factor
Goblet - mucus

113

How does the stomach produce a hypertonic chyme?

Combines action of acid, enzymes and agitation increases the number of molecules present

114

What are the main functions of the duodenum?

Dilution
Neutralisation of chyme
Iron absorption

115

How much fluid is added to the contents of the duodenum?

9 l of water/alkali

116

Where is water drawn from in the duodenum to make chyme isotonic?

ECF

117

What is the function of Brunner's glands, found above the Sphincter of Oddi?

Produce mucus rich alkaline solution to protect duodenum and inhibit gastric chief and parietal cell function

118

What do the accessory organs secrete into the chyme in the duodenum?

Liver releases bile containing water, alkali and bile salts
Pancreas secretes alkali and enzymes

119

How is digestion of chyme completed in the duodenum?

Secretion of enzymes by pancreas, liver and intestine

120

What so the function of the jejunum?

Absorption of most nutrients

121

What forms the jejunal mucosa?

Simple columnar epithelium
Lamina propria
Muscularis mucosa with microvilli and goblet cells

122

What are pliae circulares?

Permanent circular folds of mucosa and submucosa that project into the jejunal lumen

123

Why is gut transit reduced in the jejunum?

To give adequate time for absorption

124

Describe the absorption which takes place in the jejunum.

Most active takes place proximally
Absorbs mainly sugars and a.a.

125

What is the main function of the large intestine?

Drying of contents (although jejunum actually absorbs more water)

126

How are useful small molecules absorbed in the large intestine?

By bacteria involved in vitamin synthesis and enterocytes

127

What epithelium lines the large intestine?

Simple columnar with attached enzymes, crypts of Lieberkühn and lymphatic tissue

128

What vitamins are synthesised by bacteria in the large intestine?

K
B12
Thiamine
Riboflavin

129

What causes the urge to defecate?

Rapid propulsion of colonic contents into rectum causing it to stretch

130

What can overcome the urge to defecate?

Reverse peristalsis

131

How much water is removed from the colonic contents by the large intestine?

1.35 l

132

How much water is removed from the contents in the small intestine?

12.5 l