The Small Intestine Flashcards

1
Q

what is the small bowel

A

the small intestine

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2
Q

what are the three sections that make up the small intestine

A

duodenum
jejunum
ileum

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3
Q

what is the small intestine the primary site for in the body

A

digestion and absorption

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4
Q

where does the small intestine begin

A

the pylorus

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5
Q

where does the small intestine extend to

A

the ileocaceal junction

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6
Q

how long is the duodenum

A

twelve finger lengths, around 25-30cm

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7
Q

why is the jejunum typically empty at post mortem

A

the result of terminal peristalsis

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8
Q

what does the name jujunum come from

A

latin for empty and fasting

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9
Q

what is the peritoneum

A

a continuous membrane lining the abdominal cavity and covers the abdominal viscera

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9
Q

what does the name ileum come from

A

latin for twisting

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9
Q

what is the parietal peritoneum sensitive to

A

pressure, pain, temperature

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9
Q

what is the function of the peritoneum

A

support abdominal organs and provide a route for blood vessels

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9
Q

what does the visceral peritoneum cover

A

the majority of the abdominal visera.

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9
Q

where does pain from the visceral peritoneum transfer to

A

dermatomes

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9
Q

what is the serous membrane

A

two layers continous with each other that are made up of simple squamous epithelial cells called mesothelium

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10
Q

what are intraperitoneal organs enveloped by

A

visceral peritoneum

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10
Q

what are dermatomes

A

areas of skin supplied by a single spinal nerve

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10
Q

what does the visceral peritoneum envelope

A

the intraperitoneual organs

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10
Q

what are the retroperitoneal organs

A

duodenum, pancreas and rectum

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10
Q

what does the mesentry connect structure to

A

the posterior abdominal wall

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10
Q

what is the mesentry

A

a double layer of visceral peritoneum, connecting the structure to the posterior abdominal wall. the mesentry contains blood vessels, nerves and lymphatics.

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11
Q

what does the mesentry contain

A

blood vessels
nerves
lymphatics

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11
Q

what is the omentum

A

a sheet of visceral peritoneum extending from the stomach and proximal duodenum to other abdominal organs

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12
Q

where does chyme come from

A

the stomach

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13
Q

where are brunners glands

A

above where the pancreatic and biliary secretions enter to duodenum

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14
Q

what do brunners glands secrete

A

alkaline and mucous secretions

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15
Q

what is the function of brunners glands

A

to produce alkaline and mucous secretions to protect the duodenum from the acidity of chyme, and provide optimal condition for intestinal enzymes to be active and for lubrication

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16
Q

where is bile stored

A

the gall bladder

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17
Q

how does bile enter the duodenum of the small intestine

A

the sphincter of oddi

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18
Q

what does the sphincter of oddi do

A

controls the flow of bile and the pancreatic juice, or enzymes as they pass into the duodenum

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19
Q

where does the duodenum end

A

the duodenojejunal junction

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20
Q

what secretions enter the small intestine

A

bile and pancreatic juice

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21
Q

where is the duodenum found in relation to the vertebrae

A

sits between L1 and L3/4

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22
Q

what is the shape of the duodenum

A

C shaped

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23
Q

why is the duodenum C shaped

A

it comes from the pyloric sphincter through to the duodenojejunal flexure

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24
Q

what does the sphincter of oddi control

A

the pancreatic and biliary secretions

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25
Q

where is the sphincter of oddi found

A

the second of the four parts of the duodenum

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26
Q

what is the major duodenal papillae surrounded by

A

the sphincter of oddi

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27
Q

what is the major duodenal papilla

A

the rounded projection at the opening of the common bile duct and the pancreatic duct

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28
Q

what is the minor duodenal papilla

A

the opening of the accessory pancreatic duct - typically present in 10% of people

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29
Q

what does CCK stand for

A

cholecystokinin

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30
Q

what is CCK

A

a peptide hormone that helps to digest fat and protein. secreted by cells of the duodenum.

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31
Q

what is CCK secreted by

A

cells of the duodenum

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32
Q

when is CCK secretion at its highest

A

when there is fatty acids in the chyme entering the blood stream

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33
Q

what is the function of the CCK hormone

A

digestion of fat and protein. it also inhibits gastric emptying, but increases the release of pancreatic enzymes, as well as increasing the production of bile.

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34
Q

what does CCK inhibit

A

gastric emptying

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35
Q

how does CCK result in better fat digestion

A

increases the release of pancreatic enzymes, as well as increasing the production of bile by contraction of the gall bladder and relaxation of the sphincter of oddi

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36
Q

what are the four parts to the duodenum

A
  • superior
  • descending
  • inferior
  • ascending
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37
Q

what is the superior part to the duodenum

A

this is the cap and ascends upward from the pyrolus, it is the area that is most common to have a duodenal ulcer. sits at L1

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38
Q

what is the descending section of the duodenum

A

this passes downward around the head of the pancrea, lying behind the transverse colon, and in front of the right kidney. it is at this site where the major duodenal papilla lies. sits at the level of L1-L3

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39
Q

what is the inferior section of the duodenum

A

this portion passes to the left over the inferior vena cava and aorta. lies behind the superior mesentric artery, supplying the midgut

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40
Q

what is the ascending section of the duodenum

A

this crosse the aorta and curves up to join the jejunum at the duodenojejunal flexure

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41
Q

which section of the duodenum is supplied by the gastroduodenal artery

A

the section prior to the major duodenal papilla in the second part of the duodenum

42
Q

which section of the duodenum is supplied by the pancreaticoduodenal artery branch of the superior mesentric artery

A

the section following the major duodenal papillae

43
Q

what supplies blood to the section of the duodenum prior to the duodenal papilla

A

the gastroduodenal artery

44
Q

what supplies blood to the section of the duodenum after the duodenal papilla

A

the superior mesentric artery and its branch the pancreaticoduodenal artery

45
Q

why is there venous drainage within the duodenum

A

to portal the system either through the splenic or superior mesentric vein to the portal vein

46
Q

give a breakdown on duodenal ulcers

A

these are breaks in the epithelium, found mostly in the posterior wall of the superior section of the duodenum. the duodenum becomes red, inflammed and ulcerated, where there is damage and disruption to the duodenal epithelium. there is possibility of perforation, and the pain is typically worse at night. thers is upper abdominal pain typically relieved by eating
can lead to air under the diaphragm

47
Q

what can cause duodenal ulcerations

A

infections and non steroidal inflammatory drugs like ibuprofen

48
Q

what could cause sudden intense abdominal pain, fever, nausea and fever

A

perforation and peritonitis from a duodenal ulcer

49
Q

what are the treatment options of a perforated duodenal artery that has led to air under the diaphragm

A

surgery

50
Q

main function of the duodenum

A

digestion using pancreatic enzymes and bile

51
Q

main function of the jejunum

A

digestion with brush border enzymes and absorption

52
Q

main function of ileum

A

absorption

53
Q

give a breakdown on the layers of the intestine

A
  • lumen
  • mucosa
  • submucosa
  • muscularis externa
  • adventitia
54
Q

what are the layers to mucosa

A

epithelium, lamina propria, and muscularis mucosae

55
Q

what are the layers to the muscularis externa

A

inner circular
outer longitudinal

56
Q

what are enterocytes in the mucosa

A

tall columnar epithelium with an absorptive function

57
Q

what is the function of goblet cells in the small intestine

A

secrete mucin

58
Q

what is the function of crypts of lieberkuhn

A

this is where hormones are secreted and new stem cells are found

59
Q

what is the function of the submucosa plexus

A

these are nerves from the parasympathetic nervous system

60
Q

what is the myenertic plexus responsible for

A

motor innervation to both layers of muscle. has both parasympathetic and sympathetic innervation

61
Q

what are plicae circulares

A

permanent circular folds of mucous membranes which are most numerous in the latter part of the duodenum through the upper part of the jejunum. these increase the surface area in the small intestine.

62
Q

by how much do villi increase the surface area of the small intestine

A

10 to 30 times

63
Q

by how much do microvilli increase the surface area of the small intestine

A

600 times

64
Q

how many layers are in the serosa

A

2 layers of mesothelium

65
Q

describe the jejunum

A

located in the upper left quadrant. has a thick intestinal wall, with a longer vasa recta with straight arteries. red in colour

66
Q

features of the ileum

A

the lower right quadrant, has a shorter vasa recta, and more arcades. pink in colour. has a thin intestinal wall

67
Q

which epithelia is present in the intestine

A

simple columnar

68
Q

what is the lacteal

A

a lymphatic vessel that absorbs digested fats

69
Q

what are peyer’s patches

A

part of the gut associated lymphoid tissue which is part of the mucosa associated with the lymphoid tissue

70
Q

what does the circular layer of muscle in the intestine do

A

local contraction and breakdown

71
Q

what does the longitudinal layer of muscle in the intestine do

A

moves bolus further along as well as breaking it down

72
Q

what is the ileo-caecal junction

A

a muscular sphincter between the last part of the small intestine and the first part of the large intestine

73
Q

what is absorbed at the ileo-caecal junction

A

vitamin B12 and bile acid

74
Q

what are some clinical notes of the ileum

A

there are dietary deficiencies. malabsorption syndroms can lead to deficiences that affect blood like anaemia. this can affect the oral mucosa

75
Q

what are examples of some disorders of the intestinal tract

A

coeliac disease
crohns disease
cystic fibrosis

76
Q

what can absorbed through the stomach

A

caffeine and alcohol

77
Q

what is the peritoneum wrapped around

A

the entire abdominal cavity

78
Q

what is found in between the peritoneum and what is its function

A

secretions, in order to minimise friction.

79
Q

what is the purpose of the peritoneum

A

to hold everything together

80
Q

where is the parietal peritoneum found

A

the outside layer of the peritoneum

81
Q

where is the visceral peritoneum found

A

looping around organs

82
Q

what is the omentum a double fold of

A

mesentry

83
Q

where does the omentum hang down from

A

the stomach

84
Q

what is the function of the omentum

A

they act as abdominal police. when there is inflammation in the abdomen it starts off as generalised, the omentum then identifies where the inflammation is and wraps around the issue, causing the localised pain and tenderness

85
Q

where is the mesentry found

A

around the small intestine

86
Q

is chyme completely broken down when it reaches the small intestine

A

no

87
Q

why does acid from the stomach not harm the lining of the duodenum due to its high pH

A

the brunners glands at the start of the duodenum neutralise the acid by producing alkaline and mucous secretions

88
Q

what is the function of bile

A

aiding fat digestion

89
Q

what is the function of pancreatic enzymes

A

digestion of proteins

90
Q

where does the duodenum sit

A

close to the pancreas

91
Q

what is the spleen involved in

A

processing blood

92
Q

is the entire duodenum within the abdominal cavity

A

no, part of it sits behind the peritoneum

93
Q

what releases CCK

A

cells in the wall of the duodenum into the bloodstream

94
Q

what leads to ulcers in the duodenum

A

repeated irritation

95
Q

why is the jejunum and the ileum described as infracolic

A

it is found below the colon

96
Q

where does the jejunum start

A

at the duodenumjejunal junction

97
Q

how long is the small intestine

A

7 or 8 metres

98
Q

how long is the large intestine

A

2 metres

99
Q

what occurs in the ileum

A

nutrient absorption

100
Q

what does the adventitia do

A

holds everything together

101
Q

why are there so many nerves innervating the small intestine

A

to ensure motility happens in a coordinated fashion

102
Q

can we see villi with the naked eye

A

no

103
Q

why do pathologies affect digestion and absorption

A

because the surface area of the small intestine is so large

104
Q

describe the blood vessels of the jejunum

A

longer and not branched

105
Q

describe the blood vessels of the ileum

A

shorter and more branched

106
Q

why are the blood vessels of the ileum more branched than the jejunum

A

their degree of absorption - there needs to be more blood supply to pick up the nutrients

107
Q

what do the presence of the submucous glands aid

A

ensuring everything passes through the small intestine smoothly

108
Q

where are lacteals found

A

extending through the middle of the villi

109
Q

what is peyer’s patch a collection of

A

lymphoid tissue, or inflammatory tissue

110
Q

what feature of the ileum is used to differentiate between the ileum and the jejunum

A

the peyer’s patch

111
Q

how does intestinal mobility happen

A

by segmentation; the muscle layers have different functions for breaking down food and passing it down the tract

112
Q

what is the ileo caecal junction

A

an opening

113
Q

what is the function of the apendix

A

unknown although histological examination of the appendix reveals lymphoid tissue within it.

114
Q

what can antibiotics change regarding the gut

A

the gut flora

115
Q

what can malabsorption symptoms lead to

A

deficiences that affect blood - anaemia - which can then affect the oral mucosa

116
Q

what are meckels diverticulum

A

these are out pouches, and a disease of this is when there are multiple of them. fecal material can build up within them and create an infection. most of the time they are made up of ileal mucosa, but can have epithelium from the stomach, pancreas or the colon, which will irritate it

117
Q

what are the rules of 2 in related to meckels diverticulum

A

it occurs in 2% of the population, they are 2 inches long, and are 2 feet away from the ilia-caecal valve.

118
Q

name all the retroperitoneal organs

A
  • adrenal glands
  • aorta and vena cava
  • duodenum (descending, inferior and ascending)
  • pancreas (not the tail though)
  • ureters
  • ascending and descending colon
  • kidneys
  • oesophagus
  • rectum
119
Q
A