Gross Anatomy and Functional Histology of the Large Intestine Flashcards

1
Q

What are the structures derived from the foregut? (5)

A
  1. Respiratory tress from larynx to alveoli
  2. Esophagus
  3. Stomach
  4. Liver, gallbladder and pancreas
  5. Duodenum as far as the entrance of the common bile duct
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2
Q

What is the main blood supply of the foregut?

A

Celiac trunk at T12

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3
Q

What are the nerve innervations of the foregut?

A

Greater splanchnic and vagal nerve

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4
Q

What are the structures deruved from the midgut? (5)

A
  1. Duodenum distal to the opening of the common bile duct
  2. Jejunum and ileum
  3. Cecum and appendix
  4. Ascending colon
  5. Proximal part of transverse colon
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5
Q

What is the blood supply to the midgut?

A

Superior mesentery artery at L1

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6
Q

What is the nerve innervation of the midgut?

A

Lesser thoracic splanchnic and vagal nerve

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7
Q

What are the structures derived from the hindgut? (4)

A
  1. Distal part of the transverse colon
  2. Descending colon
  3. Sigmoid colon
  4. Rectum and upper part of anal canal
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8
Q

Where is the lower part of the anal canal derived from?

A

Ectoderm

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9
Q

What is the parasympathetic nerve innervation of the hindgut?

A

Pelvic splanchnic nerves (S2 - 4)

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10
Q

What kind of nerves innervate the lower part of the GIT?

A

Sacral nerves, not cranial

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11
Q

What is the blood supply to the hindgut?

A

Inferior mesenteric artery at L3

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12
Q

What is the sympathetic innervation of the hindgut?

A

Lumbar splanchnic nerves

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13
Q

What is the cloaca separated into?

A

Urogenita sinus
Rectonanal sinus

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14
Q

What does the urogenital sinus contribute in?

A

Formation of the urinary bladder and the urethra

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15
Q

What does the rectoanal canal contribute in?

A

Formation of the rectum and upper part of the anal canal

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16
Q

What is the allantoid?

A

Connection between the urinary bladder and the yolk sac

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17
Q

Which other structure is the allantoid similar to?

A

Viteline duct

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18
Q

What does the tip of the urorectal septum divide into?

A

Urogenital membrane
Anal membrane

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19
Q

Up until does the urorectal septum grow?

A

Until it reaches the ectoderm

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20
Q

What is the function of the urorectal septum?

A

Separates the cloaca and the hindgut into anterior and posterior systems (membranes)

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21
Q

What is the perineal body a part of?

A

Part of the tip of the urorectal septum

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22
Q

What does the anal membrane cover?

A

Anorectal canal

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23
Q

What happens to both the urogenital and anal membranes?

A

They both degenerate so that the two systems can open into the exterior

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24
Q

Which pathology occurs if the urogenital and anal membranes do not degenerate?

A

Imperforate anus

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25
Q

What are the types of imperforate anus?

A

Anal atresia
Anal stenosis

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26
Q

What is an imperforate anus?

A

A defect in which the opening to the anus is either missing or blocked

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27
Q

What causes the imperforate anus to occur?

A

Anal membrane fails to breakdown
Deviation in the path of the growth of the urorectal septum

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28
Q

What are the main functions of the large intestine?

A

Reabsorption of H2O and salts
Absorption of vitamins
Storage of feces

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29
Q

Which of the structures of the large intestine are intraperitoneal or attached to a mesentery?

A

Cecum (no specific mesentery but still has motility)
Appendix
Transverse colon
Sigmoid colon
Upper 1/3 of rectum

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30
Q

Which of the structures of the large intestine are retroperitoneal or have no mesentery attached to them?

A

Ascending colon
Descending colon
Middle 1/3 of the rectum

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31
Q

What kind of structure is the lower 1/3 of the rectum?

A

Infraperitoneal

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32
Q

What happens if the appendix gets obstructed or inflammed?

A

Appendecitis

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33
Q

What are taeniae coli?

A

Bands of muscle of the large intestine, form a layer around the appendix

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34
Q

Which artery is specific to the appendix?

A

Appendicular artery

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35
Q

Where is appendicular artery derived from?

A

The posterior cecal artery

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36
Q

Why is it important to know the location of the appendicular artery?

A

In the case of appendectomy, this artery has to be ligated

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37
Q

What is the location of the orifice of the appendix in regard to the ileocecal sphincter?

A

The office of the appendix is inferior to the ileocecal sphincter

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38
Q

What are the nerve supplies of the appendix?

A

Autonomic nerve fibers and afferent nerve fibers

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39
Q

Where is the initial pain of appendicitis?

A

Initial pain would be at the umbilicus area. Afterward, it migrates to the right lower quadrant at the site of the appendix

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40
Q

What is the most common location of the appendix?

A

Retrocecal location, the appendix is just behind the cecum

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41
Q

What are the other possible locations of the appendix? Describe them

A

Pelvic (32%) (Just behind the pelvis)
Paracecal (On the side of the cecum)
Subcecal (Under the cecum)
Preileal (Anterior to the ileum)
Postileal (Posterior to the ileum)

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42
Q

How does the pain relate to the location of the appendix?

A

With appendicitis, based on the location of the appendix, the pain will be different

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43
Q

What are the characteristics of the large intestine?

A

Hasutrae
Appendices epiploicae
Taenia coli

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44
Q

What are the divisions of the colon?

A

Ascending
Transverse
Descending
Sigmoid

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45
Q

What causes the haustrae in the large intestine?

A

Sacculations

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46
Q

Where does the large intestine end?

A

At the anus

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47
Q

What are the sphincters of the anus?

A

Internal anal
External anal

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48
Q

Which is the voluntary and which is the involuntary anal sphincter?

A

Internal sphincter –> Involuntary
External sphincter –> Voluntary

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49
Q

What is the muscle of the internal anal sphincter?

A

Smooth muscle

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50
Q

Which anal sphincter is made up of skeletal muscle?

A

External anal sphincter

51
Q

What are the branches of the superior mesenteric artery that are related to the large intestine?

A

Ileocolic artery
Middle colic artery
Right colic artery

52
Q

What are the branches of the ileocolic artery?

A

Terminal ileal artery
Anterior caecal artery
Posterior caecal artery

53
Q

Which artery is the appendicular artery a branch of?

A

Posterior ceacal artery

54
Q

Which structures form the marginal arteries?

A

Both the midgut and hindgut

55
Q

Which structure does the marginal artery supply?

A

The colon

56
Q

What is the blood supply of the large intestine like and why?

A

Dual blood supply from both superior and inferior mesenteric arteries because some of the structures are derived from the midgut, and some others are from the hindgut

57
Q

What are the branches of the inferior mesenteric artery related to the large intestine?

A

Left colic artery
Sigmoidal arteries
Superior rectal artery

58
Q

What structures does the left colic artery supply?

A

Distal part of the descending colon

59
Q

What structures do the sigmoidal arteries supply?

A

The sigmoidal colon

60
Q

Where are the middle and inferior renal arteries derived from?

A

Internal iliac artery

61
Q

Which veins are direct banches of the portal vein?

A

Splenic vein
Superior mesenteric artery

62
Q

Which veins directly drain inro the portal vein?

A

Right gastric vein
Left gastric vein
Cystic vein

63
Q

Which vein does the middle rectal vein drain into?

A

Internal iliac vein

64
Q

Which vein does the inferior rectal vein drain into?

A

Internal pudendal vein

65
Q

Which veins are part of the portosystemic anastomosis?

A

Superior rectal vein
Middle rectal vein
Inferior rectal vein

66
Q

Which veins drain into the inferior mesenteric vein?

A

Left colic
Sigmoid
Superior rectal

67
Q

Which are the veins that drain into the splenic vein? (4)

A

Left gastroepiploic
Short gastric
Pancreatic
Inferior mesenteric

68
Q

Which are the veins that drain into the ileocolic vein?

A

Anterior cecal
Posterior cecal

69
Q

Which veins drain into the superior mesenteric vein? (7)

A

Right gastroepiploic
Inferior pancreatiduodenal
Middle colic
Right colic
Ileocolic
Jejunal
Ileal

70
Q

What are the layers of the large intestine?

A

Mucosa
Submucosa
Muscularis
Serosa

71
Q

What are the layers of the mucosa of the large intestine?

A

Epithelium
Lamina propria
Muscularis mucosa

72
Q

What is the histology of the epithelium of the mucosa of the large intestine?

A

Simple columnar

73
Q

What are the cells found in the epithelium of the large intestine?

A

Absorptive cells
Goblet cells
Regenerative cells
Enteroendocrine cells

74
Q

What is the main kind of cells in the epithelium of the large intestine?

A

Absorptive cells

75
Q

What is the function of goblet cells in the large intestine and what happens to their number?

A

Lubricate the lumen and they increase in number as you go down the GIT

76
Q

Why are regenerative cells crucial in the large intestine?

A

Needed because of the shedding

77
Q

What is the layer of submucosa?

A

Submucosal plexus (Meissner)

78
Q

What are the layers of the muscularis of the large intestine?

A

Inner circular
Myenteric plexus (Auerbach)
Outer longitudinal

79
Q

What is the layer of the serosa of the large intestine?

A

Mesentery

80
Q

Which muscle makes up the taenia coli?

A

Outer longitudinal

81
Q

Which structure is the only one that is fully covered by outer longitudinal muscle?

A

The appendix

82
Q

If you were to look at the mesoappendix cross-section, what would you see?

A

Appendicular artery

83
Q

Why are there aggregate lymphoid nodules?

A

It is mainly formed from lymphoid tissue

84
Q

What is the number of goblet cells like in the rectum?

A

The rectum is packed with goblet cells

85
Q

What happens in the rectoanal junction?

A

Sudden change in the lining of the epithelium
The simple columnar epithelium with tubular intestinal glands in the rectum changes to stratified squamous epithelium in the anal canal

86
Q

What is the epithelium of the anal canal like and what changes occur to it?

A

It will initially be non-keratinized and by the time it reaches the lower part (ectoderm), where it will change into keratinized

87
Q

What is the mobility of the small intestine like?

A

Duodenum is the only non mobile structure

88
Q

What is the mobility of the large intestine like?

A

Ascending and descending colons are fixed

89
Q

What is the mesentery like in the small intestine?

A

Small intestine has a mesentery except of the duodenum

90
Q

Which structures of the large intestine have mesenteries?

A

Appendix, transverse and sigmoid colons

91
Q

What is the caliber of the intestines like?

A

Small intestine: smaller caliber
Large intestine: larger caliber

92
Q

What is the longitudinal muscle of the intestines like?

A

Small intestine: continuous later
Large intestine: taenia coli

93
Q

What is the fatty tags of the intestines like?

A

Small intetsine: has no fatty tags
Large intestine: Appendices epiploicae

94
Q

What is the wall of the intestines like?

A

Small intestine: smooth
Large intestine: sacculated

95
Q

What is the mucous membrances of the small intestine like?

A

Plucae circulares
Villi
Peyer’s patches

96
Q

What are the mucous membranes of the large intestine like?

A

Absent

97
Q

What is the pathology of aganglionic megacolon?

A

Hirschprung’s Disease

98
Q

What is aganglionic megacolon?

A

Developmental disorder, characterized by the absence of the ganglia in the distal colon!!!!

99
Q

What causes aganglionic megacolon?

A

Failure of migration of neural crest cells between 4th and 7th week of gestation

100
Q

What is the result of aganglionic megacolon?

A

Results in functional obstruction

101
Q

What is a megacolon?

A

Colon is dilated with feces and gases prior to obstruction

102
Q

What is intussusception?

A

Telescoping of a proximal segment of the bowel into the lumen of an adjoining distal segment

103
Q

What is the risk of intussusception?

A

Risk of cutting off the blood supply to the gut

104
Q

Which population is intussusception common in?

A

Common in children

105
Q

Which segment is most commonly affected by intussusception?

A

Ileocolic region

106
Q

What is diverticulosis?

A

A common clinical condition where there is herniation of the lining of the mucosa through the circular muscle between the teniae coli

107
Q

Where does diverticulosis occur?

A

At the point where circular muscle is the weakest

108
Q

Why is it important to know the lymphatic drainage of an organ?

A

Important for metastasis in cancer and also infection spread

109
Q

What does the lymph drainage usually follow?

A

The blood supply of an organ

110
Q

Where does the anterior aspect of the diaphragmatic surface and part of the visceral surface of the liver drain its lymph?

A

Hepatic lymph nodes and then into celiac nodes

111
Q

Where does the posterior aspect of the diaphragmatic surface and the rest of the visceral surface of the liver drain its lymph?

A

Phrenic lymph nodes, which communicate with mediastinal nodes

112
Q

What is the lymph drainage of the large intestine? (8)

A

Middle colic
Right colic
Superior mesenteric
Ileocolic
Epiploic
Intermediate colic
Paracolic
Inferior mesenteric

113
Q

What are the lymph nodes of the posterior abdominal wall?

A

Para-aortic and Preaortic

114
Q

What structures do the preaortic lymph nodes drain?

A

GI tract from the lower 1/3 of the esophagus to halfway down the anal canal
Gallbladder
Pancreas
Greater part of the liver
Spleen

115
Q

Why is it specifically only the greater part of the liver that drains into the preaortic lymph nodes?

A

The bare area is not drained in the preaortic lymph nodes

116
Q

What are the different lymph drainage station of the preaortic lymph drainage?

A

Celiac
Superior mesenteric
Inferior mesenteric

117
Q

Where ae the preaortic lymph nodes located?

A

Anterior to the aorta

118
Q

What is the largest lymphatic channel in the body?

A

Thoracic duct

119
Q

What does the thoracic duct originate from?

A

Cisterna chyli in the abdomen
Ascends through aortic hiatus

120
Q

Where does the thoracic duct run into?

A

In the posterior mediastinum, between aorta, azygous vein and esophagus

121
Q

What does the thoracic duct drain?

A

Junction of the left jugular and left subclavian vein and lower hepatic part

122
Q

Which trunks does the thoracic duct receive?

A

Jugular, subclavian, and bronchomediastinal trunks

123
Q
A