The Small Intestine Flashcards
1
Q
what is the small bowel
A
the small intestine
2
Q
what are the three sections that make up the small intestine
A
duodenum
jejunum
ileum
3
Q
what is the small intestine the primary site for in the body
A
digestion and absorption
4
Q
where does the small intestine begin
A
the pylorus
5
Q
where does the small intestine extend to
A
the ileocaceal junction
6
Q
how long is the duodenum
A
twelve finger lengths, around 25-30cm
7
Q
why is the jejunum typically empty at post mortem
A
the result of terminal peristalsis
8
Q
what does the name jujunum come from
A
latin for empty and fasting
9
Q
what is the peritoneum
A
a continuous membrane lining the abdominal cavity and covers the abdominal viscera
9
Q
what does the name ileum come from
A
latin for twisting
9
Q
what is the parietal peritoneum sensitive to
A
pressure, pain, temperature
9
Q
what is the function of the peritoneum
A
support abdominal organs and provide a route for blood vessels
9
Q
what does the visceral peritoneum cover
A
the majority of the abdominal visera.
9
Q
where does pain from the visceral peritoneum transfer to
A
dermatomes
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
10
Q
what are intraperitoneal organs enveloped by
A
visceral peritoneum
10
Q
what are dermatomes
A
areas of skin supplied by a single spinal nerve
10
Q
what does the visceral peritoneum envelope
A
the intraperitoneual organs
10
Q
what are the retroperitoneal organs
A
duodenum, pancreas and rectum
10
Q
what does the mesentry connect structure to
A
the posterior abdominal wall
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.
11
Q
what does the mesentry contain
A
blood vessels
nerves
lymphatics
11
Q
what is the omentum
A
a sheet of visceral peritoneum extending from the stomach and proximal duodenum to other abdominal organs
12
Q
where does chyme come from
A
the stomach
13
where are brunners glands
above where the pancreatic and biliary secretions enter to duodenum
14
what do brunners glands secrete
alkaline and mucous secretions
15
what is the function of brunners glands
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
16
where is bile stored
the gall bladder
17
how does bile enter the duodenum of the small intestine
the sphincter of oddi
18
what does the sphincter of oddi do
controls the flow of bile and the pancreatic juice, or enzymes as they pass into the duodenum
19
where does the duodenum end
the duodenojejunal junction
20
what secretions enter the small intestine
bile and pancreatic juice
21
where is the duodenum found in relation to the vertebrae
sits between L1 and L3/4
22
what is the shape of the duodenum
C shaped
23
why is the duodenum C shaped
it comes from the pyloric sphincter through to the duodenojejunal flexure
24
what does the sphincter of oddi control
the pancreatic and biliary secretions
25
where is the sphincter of oddi found
the second of the four parts of the duodenum
26
what is the major duodenal papillae surrounded by
the sphincter of oddi
27
what is the major duodenal papilla
the rounded projection at the opening of the common bile duct and the pancreatic duct
28
what is the minor duodenal papilla
the opening of the accessory pancreatic duct - typically present in 10% of people
29
what does CCK stand for
cholecystokinin
30
what is CCK
a peptide hormone that helps to digest fat and protein. secreted by cells of the duodenum.
31
what is CCK secreted by
cells of the duodenum
32
when is CCK secretion at its highest
when there is fatty acids in the chyme entering the blood stream
33
what is the function of the CCK hormone
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.
34
what does CCK inhibit
gastric emptying
35
how does CCK result in better fat digestion
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
36
what are the four parts to the duodenum
- superior
- descending
- inferior
- ascending
37
what is the superior part to the duodenum
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
38
what is the descending section of the duodenum
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
39
what is the inferior section of the duodenum
this portion passes to the left over the inferior vena cava and aorta. lies behind the superior mesentric artery, supplying the midgut
40
what is the ascending section of the duodenum
this crosse the aorta and curves up to join the jejunum at the duodenojejunal flexure
41
which section of the duodenum is supplied by the gastroduodenal artery
the section prior to the major duodenal papilla in the second part of the duodenum
42
which section of the duodenum is supplied by the pancreaticoduodenal artery branch of the superior mesentric artery
the section following the major duodenal papillae
43
what supplies blood to the section of the duodenum prior to the duodenal papilla
the gastroduodenal artery
44
what supplies blood to the section of the duodenum after the duodenal papilla
the superior mesentric artery and its branch the pancreaticoduodenal artery
45
why is there venous drainage within the duodenum
to portal the system either through the splenic or superior mesentric vein to the portal vein
46
give a breakdown on duodenal ulcers
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
what can cause duodenal ulcerations
infections and non steroidal inflammatory drugs like ibuprofen
48
what could cause sudden intense abdominal pain, fever, nausea and fever
perforation and peritonitis from a duodenal ulcer
49
what are the treatment options of a perforated duodenal artery that has led to air under the diaphragm
surgery
50
main function of the duodenum
digestion using pancreatic enzymes and bile
51
main function of the jejunum
digestion with brush border enzymes and absorption
52
main function of ileum
absorption
53
give a breakdown on the layers of the intestine
- lumen
- mucosa
- submucosa
- muscularis externa
- adventitia
54
what are the layers to mucosa
epithelium, lamina propria, and muscularis mucosae
55
what are the layers to the muscularis externa
inner circular
outer longitudinal
56
what are enterocytes in the mucosa
tall columnar epithelium with an absorptive function
57
what is the function of goblet cells in the small intestine
secrete mucin
58
what is the function of crypts of lieberkuhn
this is where hormones are secreted and new stem cells are found
59
what is the function of the submucosa plexus
these are nerves from the parasympathetic nervous system
60
what is the myenertic plexus responsible for
motor innervation to both layers of muscle. has both parasympathetic and sympathetic innervation
61
what are plicae circulares
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
by how much do villi increase the surface area of the small intestine
10 to 30 times
63
by how much do microvilli increase the surface area of the small intestine
600 times
64
how many layers are in the serosa
2 layers of mesothelium
65
describe the jejunum
located in the upper left quadrant. has a thick intestinal wall, with a longer vasa recta with straight arteries. red in colour
66
features of the ileum
the lower right quadrant, has a shorter vasa recta, and more arcades. pink in colour. has a thin intestinal wall
67
which epithelia is present in the intestine
simple columnar
68
what is the lacteal
a lymphatic vessel that absorbs digested fats
69
what are peyer's patches
part of the gut associated lymphoid tissue which is part of the mucosa associated with the lymphoid tissue
70
what does the circular layer of muscle in the intestine do
local contraction and breakdown
71
what does the longitudinal layer of muscle in the intestine do
moves bolus further along as well as breaking it down
72
what is the ileo-caecal junction
a muscular sphincter between the last part of the small intestine and the first part of the large intestine
73
what is absorbed at the ileo-caecal junction
vitamin B12 and bile acid
74
what are some clinical notes of the ileum
there are dietary deficiencies. malabsorption syndroms can lead to deficiences that affect blood like anaemia. this can affect the oral mucosa
75
what are examples of some disorders of the intestinal tract
coeliac disease
crohns disease
cystic fibrosis
76
what can absorbed through the stomach
caffeine and alcohol
77
what is the peritoneum wrapped around
the entire abdominal cavity
78
what is found in between the peritoneum and what is its function
secretions, in order to minimise friction.
79
what is the purpose of the peritoneum
to hold everything together
80
where is the parietal peritoneum found
the outside layer of the peritoneum
81
where is the visceral peritoneum found
looping around organs
82
what is the omentum a double fold of
mesentry
83
where does the omentum hang down from
the stomach
84
what is the function of the omentum
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
where is the mesentry found
around the small intestine
86
is chyme completely broken down when it reaches the small intestine
no
87
why does acid from the stomach not harm the lining of the duodenum due to its high pH
the brunners glands at the start of the duodenum neutralise the acid by producing alkaline and mucous secretions
88
what is the function of bile
aiding fat digestion
89
what is the function of pancreatic enzymes
digestion of proteins
90
where does the duodenum sit
close to the pancreas
91
what is the spleen involved in
processing blood
92
is the entire duodenum within the abdominal cavity
no, part of it sits behind the peritoneum
93
what releases CCK
cells in the wall of the duodenum into the bloodstream
94
what leads to ulcers in the duodenum
repeated irritation
95
why is the jejunum and the ileum described as infracolic
it is found below the colon
96
where does the jejunum start
at the duodenumjejunal junction
97
how long is the small intestine
7 or 8 metres
98
how long is the large intestine
2 metres
99
what occurs in the ileum
nutrient absorption
100
what does the adventitia do
holds everything together
101
why are there so many nerves innervating the small intestine
to ensure motility happens in a coordinated fashion
102
can we see villi with the naked eye
no
103
why do pathologies affect digestion and absorption
because the surface area of the small intestine is so large
104
describe the blood vessels of the jejunum
longer and not branched
105
describe the blood vessels of the ileum
shorter and more branched
106
why are the blood vessels of the ileum more branched than the jejunum
their degree of absorption - there needs to be more blood supply to pick up the nutrients
107
what do the presence of the submucous glands aid
ensuring everything passes through the small intestine smoothly
108
where are lacteals found
extending through the middle of the villi
109
what is peyer's patch a collection of
lymphoid tissue, or inflammatory tissue
110
what feature of the ileum is used to differentiate between the ileum and the jejunum
the peyer's patch
111
how does intestinal mobility happen
by segmentation; the muscle layers have different functions for breaking down food and passing it down the tract
112
what is the ileo caecal junction
an opening
113
what is the function of the apendix
unknown although histological examination of the appendix reveals lymphoid tissue within it.
114
what can antibiotics change regarding the gut
the gut flora
115
what can malabsorption symptoms lead to
deficiences that affect blood - anaemia - which can then affect the oral mucosa
116
what are meckels diverticulum
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
what are the rules of 2 in related to meckels diverticulum
it occurs in 2% of the population, they are 2 inches long, and are 2 feet away from the ilia-caecal valve.
118
name all the retroperitoneal organs
- 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
