9. Abdomen & Digestive System (TT) Flashcards
(248 cards)
1
Q
How can the anterior abdominal wall be divided into different section?
A
Note: You can use either the trans-pyloric plane (L1) or the subcostal plane (L3) as the top line.
2
Q
Draw a simpler way of dividing the anterior abdominal wall into sections.
A
3
Q
Describe the position of the liver and gall bladder in surface anatomy of the anterior abdominal wall.
A
- Liver -> Right upper quadrant with left lobe reaching the left upper quadrant
- Gall bladder -> Lies in the transpyloric plane close to the right edge of rectus abdominis.
4
Q
Describe the position of the stomach in surface anatomy of the anterior abdominal wall.
A
Mainly in the left upper quadrant, with the pylorus crossing the midline.
5
Q
Describe the position of the caecum in surface anatomy of the anterior abdominal wall.
A
Right lower quadrant.
6
Q
Describe the position of the descending colon in surface anatomy of the anterior abdominal wall.
A
Left lumbar region
7
Q
Describe the 3 muscle layers of the anterior abdominal wall and the direction of their fibres. [IMPORTANT]
A
8
Q
What is the line called that runs along the midline of your abs?
A
Linea alba
9
Q
What is the inguinal ligament, where does it attach and what forms it?
A
- It is the aponeurosis of the external oblique muscles
- It attaches at the anterior superior iliac spine and pubic tubercle
- It forms part of the boundaries of the inguinal canal
10
Q
What is the conjoint tendon and what forms it?
A
- It is the lower part of the common aponeurosis of the internal oblique muscle and the transversus abdominis
- It forms part of the boundaries of the inguinal canal
11
Q
What are the different layers that constitute the anterior abdominal wall? [IMPORTANT]
A
12
Q
What are the abdominal muscles closest to the midline called?
A
Rectus abdominis
13
Q
What are the rectus abdominis muscles contained within?
A
A sheath formed by the aponeuroses of abdominal wall muscles & transversalis fascia.
14
Q
Where do the rectus abdominis muscles attach?
A
- Superiorly at the costal margin
- Inferiorly at the pubic bone
15
Q
Describe the innervation of the anterior and anterolateral abdominal walls.
A
Ilioinguinal and iliohypogastric nerves innervate the lower parts of the abdomen.
16
Q
Where do the lateral cutaneous nerves that innervate the abdominal wall travel?
A
Between the internal oblique and transversus abdominis muscle layers.
17
Q
Draw the dermatomes of the anterior abdominal wall.
A
18
Q
Describe the descent of the testis. [IMPORTANT]
A
- The gubernaculum guides the descent of the testis through all of the layers of the abdominal wall except the parietal peritoneum
- However, the peritoneum is pulls down with the testis
- The canal the peritoneum forms is called the processus vaginalis
- The peritoneum gives rise to a covering of the testis called the tunica vaginalis
19
Q
How does an inguinal hernia occur? [IMPORTANT]
A
When the testes descend, if there is a patent processus vaginalis, the contents of the peritoneal cavity can herniate into the scrotum.
20
Q
What important structure does the descent of the testis give rise to?
A
Inguinal canal
21
Q
Does the inguinal canal also exist in females?
A
Yes
22
Q
What is found at either end of the inguinal canal?
A
- Deep inguinal ring -> On the proximal side
- Superficial inguinal ring -> On the distal side
23
Q
Show how the inguinal canal can be found using surface anatomy.
A
24
Q
What forms each side of the inguinal canal?
A
- Roof -> Arching fibres of internal oblique & transversus abdominis
- Anterior wall -> External oblique aponeurosis
- Posterior wall -> Transversalis fascia; medially, the conjoint tendon
- Floor -> Infolding of inguinal ligament
25
What are the contents of the inguinal canal in females?
* Round ligament of uterus
* Ilioinguinal nerve
* Genital branch of the genitofemoral nerve
26
What are the contents of the inguinal canal in males?
* Spermatic cord and contents
* Ilioinguinal nerve
* Genital branch of the genitofemoral nerve
27
Label this view of the inguinal canal from the posterior side (from within the abdomen).
28
On this image, you can see the deep inguinal ring. Label roughly where the superficial inguinal ring is.
29
The deep inguinal ring is an outpouching of...
The transversalis fascia.
30
Describe the position of the deep inguinal ring relative to the epigastric vessels.
It is lateral to the vessels.
31
What are the boundaries of Hesselbach's triangle?
* Inguinal ligament
* Inferior epigastric vessels
* Rectus abdominis
32
Compare an indirect and direct inguinal hernia.
Indirect:
* Congenital
* Contents pass through deep inguinal ring, inguinal canal and then the superficial inguinal ring
Direct:
* Not congenital
* Contents buldge out through a weakness in Hesselbach's triangle and pass through the superficial inguinal ring -\> Do not pass through deep inguinal ring or inguinal canal
33
Where can the root of an inguinal hernia be felt?
It lies above the pubic tubercle (since the superficial inguinal ring is above the inguinal ligament, which attaches to the tubercle).
34
Draw the position of the femoral canal.
It is the space within the femoral sheath that contains the femoral artery and vein (but not nerve).
35
Where do the foregut, midgut and hindgut stretch from and to?
* Foregut -\> Inferior oesophagus to midway along duodenum
* Midgut -\> Midway along duodenum to 2/3rd along the transverse colon
* Hindgut -\> 2/3rd along the duodenum to the rectum
36
Describe the blood supply and innervation of the foregut.
* Blood: Coeliac artery
* Innervation: T5-T9
37
Describe the blood supply and innervation of the midgut.
* Blood: Superior mesenteric artery
* Innervation: T10-T11
38
Describe the blood supply and innervation of the hindgut.
* Blood: Inferior mesenteric artery
* Innervation: T12-L1
39
Describe the referred pain regions of the foregut, midgut and hindgut.
40
What is the abdomen and what are the two parts?
* It is the region of the body below the diaphragm.
* Two parts:
* Abdomen proper
* Pelvic cavity
41
What are the two layers of the peritoneum?
* Visceral -\> Covers organs
* Parietal -\> Covers the walls of the abdomen
42
Draw diagrams to show the layers of peritoneum on an intraperitoneal and retroperitoneal structures.
43
Are major nerve trunks and the aorta intraperitoneal or retroperitoneal?
Retroperitoneal
44
What are the lesser and greater omentum?
Structures related to the stomach:
* Lesser ometum -\> The double layer of peritoneum that extends from the liver to the lesser curvature of the stomach
* Greater omentum -\> A large apron-like fold of visceral peritoneum that hangs down from the anterior side of the stomach (ultimately attaches to the posterior absominal wall)
45
What forms the connection between the greater and lesser sac of the peritoneal cavity?
The lesser omentum has a free edge.
46
What are the different attachments of the liver?
* Falciform ligament -\> A ligament that attaches the liver to the front body wall
* Lesser omentum -\> Attaches the liver to the stomach (Can't see the attachment on this diagram because this is the free edge. The superior edge of the omentum attaches to the liver.)
47
What structure are the green and blue parts of this diagram derived from?
* Green -\> Derived from ventral mesentry
* Blue -\> Derived from dorsal mesentry
48
Label this cross-section.
49
Describe the position of the spleen in the abdomen.
It is just below the ribs, on the left side of the abdomen, just left and posterior to the stomach.
50
What is the role of the spleen? [IMPORTANT]
* Turnover of RBCs
* Role in immunity is studied in second year
51
Where does the oesophagus start and end?
Begins at lower laryngopharynx and ends at the stomach (~25cm long).
52
What sort of muscle is found in the oesophagus?
* Upper 1/3rd -\> Skeletal muscle
* Lower 2/3rd -\> Smooth muscle
53
At what spinal level does the oesophagus start and what structure marks this?
* C6/C7
* This is marked by the upper oesophageal sphincter
54
Describe the position of the oesophagus relative to the trachea and left atrium.
Runs posterior to:
* Trachea
* Tracheal bifurcation
* Left atrium
55
At what level does the oesophagus pass through the diaphragm?
T10
56
What is found at the gastro-oesophageal junction?
* Lower oesophageal sphincter
* This 'sphincter' largely works due to the diaphragm, which can contrict the oesophagus
* It prevents reflux from the stomach
57
What nerves run with the oesophagus and cross the diaphragm with it?
Left and right vagus nerves
58
What nerve provides parasympathetic innervation to the oesophagus?
Vagus
59
What is the name for the part of the stomach where the oesophagus enters?
Cardia
60
What are the three main parts of the stomach?
61
What are the parts of the pylorus of the stomach?
* Pyloric antrum
* Pyloric canal
* Pyloric sphincter
62
What is the pyloric sphincter?
A sphincter between the stomach and the first part of the duodenum.
63
Label this diagram of the stomach.
64
What demarcates the boundary between the fundus and body of the stomach?
The fundus is everything above the cardiac notch.
65
What demarcates the boundary between the body and pylorus of the stomach?
Angular notch
66
How many layers of muscle does the stomach have?
It has 3, which is one more than most organs:
* Longitudinal
* Circular
* Oblique
67
What is pyloric stenosis and what may it result in?
* A narrowing of the pylorus of the stomach.
* Symptoms include projectile vomiting without the presence of bile.
68
What are gastric ulcers and what are the symptoms?
* A break in the inner lining of the stomach
* Symptoms include: Abdominal pain, bloating, etc.
69
What are the 4 parts of the duodenum?
* 1st (superior)
* 2nd (descending)
* 3rd (horizontal)
* 4th (ascending)
70
Which side of the abdomen does the duodenum curve out to?
Right side
71
Between what vertebral levels is the duodenum?
L1 and L3
72
What demarcates the boundary between the foregut and the midgut?
The entry of the biliary and pancreatic ducts into the duodenum.
73
Where in the duodenum do the biliary and pancreatic ducts enter?
2nd (descending) part
74
What demarcates the point where the dudodenum becomes the jejunum?
The ligament of Treitz (which joins the duodenum to the diaphragm).
75
Is the duodenum intraperitoneal or retroperitoneal?
The first cm is mobile, but the rest is retroperitoneal.
76
Describe the blood supply to the duodenum.
77
Draw the relations of the duodenum.
78
What is the sphincter of Oddi?
The smooth muscle that surrounds the end portion of the common bile duct and pancreatic duct. This muscle relaxes during a meal to allow bile and pancreatic juice to flow into the intestine.
79
What are the ligaments on the anterior side of the liver?
80
What are the ligaments on the posterior side of the liver?
81
What is the entry/exit point of the hepatic portal vein, bile duct, hepatic artery into the liver?
82
What structures does the free edge of the lesser omentum contain?
* Common bile duct
* Hepatic artery
* Hepatic portal vein
83
What is the name for the entrance to the lesser sac?
Epiploic foramen
84
What are the three parts of the gall bladder?
* Fundus
* Body
* Neck
85
Describe the structure of the biliary system. [IMPORTANT]
* The left and right hepatic ducts drain the left and right lobes of the liver
* They converge to give the common hepatic duct
* Bile flows through this and into the cystic duct, after which it is stored in the gall bladder
* Upon eating, the bile is released from the gall bladder into the cystic duct and then into the common bile duct
* From there it passes into the duodenum
86
What height does the top of the gall bladder (fundus) reach?
9th costal cartilage
87
Describe the position of the gall bladder in the abdomen.
The fundus of the bladder is where the lateral border of the rectus abdominis muscle crosses the right 9th intercostal cartilage.
88
What is the name for gall bladder pain and where can it be referred to?
* Cholecystitis
* Can be referred to right shoulder, right hypochondrium or epigastric region
89
What structure does the upper part of the common bile duct lie within?
Free margin of the lesser omentum
90
What does the common bile duct enter the duodenum with? [IMPORTANT]
It enters the duodenum with the pancreatic duct (it enters at the hepatopancreatic ampulla).
91
Is the pancreas intraperitoneal or retroperitoneal?
Retroperitoneal
92
Describe the position of the pancreas.
It is roughly along the midline of the body, with the head tucked into the curve of the duodenum. The body and tail are off on the left side.
93
What are the different parts of the pancreas? [EXTRA]
94
What is the relation of the pancreas to the duodenum? (In terms of position and function)
* The head of the pancreas is in the curve of the duodenum
* The major duodenal papilla is a drainage point for pancreatic and hepatic (bile) secretions
* The minor duodenal papilla also receives the accessory pancreatic duct
95
Describe the relation of different parts of the pancreas to surrounding organs and structures.
96
Draw how an annular pancreas occurs. [EXTRA]
97
Name the different parts of the small and large intestine.
Small intestine:
* Duodenum
* Jejunum
* Ileum
Large intestine:
* Ascending colon -\> Including caecum and appendix
* Transverse colon
* Descending colon
* Sigmoid colon
* Rectum
98
How long is each part of the small intestine?
* Duodenum -\> 25cm
* Jejunum -\> 2.5m
* Ileum -\> 3.5m
99
Are the parts of the small intestine intraperitoneal or retroperitoneal?
* Start of duodenum -\> Intraperitoneal
* Rest of duodenum -\> Retroperitoneal
* Jejunum -\> Intraperitoneal
* Ileum -\> Intraperitoneal
100
How is the small intestine suspended in the abdomen?
It is attached by a mesentry to the posterior abdominal wall.
101
Compare the structure of the jejunum and the ileum.
The ileum has smaller and fewer mucosal folds than the jejunum.
102
Label this large intestine.
103
Describe the appearance of longitudinal muscle in the large intestine.
It is condensed into thin stripes called taeniae coli.
104
What are the puffy parts of the large intestine called?
Haustra
105
On which side of the body is the ascending colon?
Right
106
What prevents reflux from the caecum to the ileum?
Ileocaecal valve
107
Which parts of the large intestine are retroperitoneal and which are intraperitoneal?
* Caecum -\> Intraperitoneal
* Ascending colon -\> Secondary retroperitoneal
* Transverse colon -\> Intraperitoneal
* Descending colon -\> Secondary retroperitoneal
* Sigmoid colon -\> Intraperitoneal
* Rectum -\> Superior 2/3rd retroperitoneal
108
Describe the position of the appendix of the large intestine.
It is at the start of the caecum, although the direction it points in is variable.
109
What artery supplies the appendix of the large intestine?
Appendicular artery (originating from the superior mesenteric artery)
110
What is appendicitis and what are the symptoms? [IMPORTANT]
* It is inflammation of the appendix of the large intestine, usually due to infection
* Symptoms:
* Initial pain around the bellybutton due to the appendix being innervated by the T10 nerve root
* Pain later at McBurney's point
111
At what vertebral level does the rectum begin?
S3
112
Where is the anorectal junction?
It is at the point when the rectum pierces the pelvic floor muscles.
113
What are the folds in the rectum called? Describe them.
They are called the 'valves of Houston':
* 2 are on the left
* 1 is on the right
114
Compare the muscles and innervation of the two anal sphincters.
* Internal anal sphincter:
* Smooth muscle
* Autonomic control
* External anal sphincter:
* Striated muscle
* Pudendal nerve (s2-S4) control
115
Which nerve and nerve roots innervate the external anal sphincter?
* Pudendal nerve
* S2-S4
116
What does the coeliac artery arise from?
Aorta (at the T12 level)
117
Describe what the coeliac artery supplies (and via what arteries it does this).
It has 3 main branches:
* Left gastric artery
* Lower part of oesophagus
* Stomach (anterior + posterior)
* Splenic artery
* Spleen
* Pancreas
* Stomach
* Common hepatic artery
* Stomach
* Duodenum
* Liver
118
Describe the drainage of the GI tract.
* All of the blood ultimately drains into the liver via the hepatic portal vein
* The hepatic portal vein is formed by the confluence of the splenic vein and the superior mesenteric vein
* The inferior mesenteric vein drains into the splenic vein before the confluence
* The organs drained by each are similar to those supplied by the corresponding arteries
119
What are portosystemic anastamoses?
* A specific type of anastomosis that occurs between the veins of the portal circulation and those of the systemic circulation.
* These mean that blood from the viscera can go to the heart instead of via the liver, and vice versa.
120
When can portosystemic anastomoses open?
When pressure in the portal venous system increases.
121
What are the 5 main sites of portosystemic anastomoses?
* Inferior oesophagus
* Portal: Left gastric veins
* Systemic: Oesophageal veins (tributaries to the azygos veins)
* Wall of the anal canal
* Umbilicus
* Rectum
* Bare area of liver
122
Describe the blood supply to the liver and gall bladder.
* Right and left hepatic arteries supply the liver
* The cystic artery (a branch of the right hepatic artery) supplies the gall bladder
123
Describe the blood supply to the pancreas.
It forms at the junction between the foregut and midgut, so it is supplied by both the coeliac and superior mesenteric arteries:
* Splenic artery (from coeliac artery)
* Anterior superior pancreaticoduodenal artery (from coeliac artery)
* Anterior inferior pancreaticoduodenal artery (from superior mesenteric artery)
124
What are the branches of the superior mesenteric artery?
125
What does the superior mesenteric artery arise from and at what vertebral level?
* Arises from the aorta, just below the coeliac artery
* It is at the L1 level
126
What are the branches of the inferior mesenteric artery?
127
What does the inferior mesenteric artery arise from and at what vertebral level?
* Arises from the aorta
* At the L3 level
128
Describe the blood supply to the rectum.
Superior part of the rectum:
* Superior rectal artery, which is a branch of the inferior mesenteric artery
Middle part of the rectum:
* Middle rectal artery, which is a branch of the internal iliac artery
Inferior part of the rectumL
* Inferior rectal artery, which is a branch of the pudendal artery, which is a branch of the internal iliac artery
129
Describe the venous drainage of the rectum. [EXTRA]
* Superior rectal vein -\> Drains to inferior mesenteric vein (portal system)
* Middle rectal vein + Inferior rectal vein -\> Drain to internal pudendal vein, then internal iliac vein, then IVC
130
What are the different ways we can image the GI tract?
* Plain films
* Barium studies
* CT colonography and virtual colonoscopy
* MR Enterography
* Angiography: CT and digital subtraction angiography
131
Compare the appearance of the small and large bowel on CT.
132
What element is useful as a contrast agent for imaging the GI tract? [EXTRA]
Barium
133
What is virtual colonoscopy?
* It is an alternative to conventional colonoscopy.
* Instead of the barium contrast CT scan, the patient's bowel is pumped full of air and then a CT scan is done, which is reconstructed digitally to give a model of how the bowels look
134
At what height do the coeliac, superior mesenteric and inferior mesenteric arteries branch off the aorta?
* Coeliac artery -\> T12
* Superior mesenteric artery -\> L1
* Inferior mesenteric artery -\> L3
135
At what height does the aorta bifurcate (into the common iliac arteries)?
L4
136
Draw the different branches of the aorta.
137
Label this CT of the abdomen.
138
What are 3 important structural features of tissues of the alimentary tract?
1. Modified epithelium
* Secretion/absorption/ protection
2. Well developed immune system
* Protection -\> Exposed to vast array of pathogens
3. Stem Cells
* Regeneration -\> Cell replacement
139
What percentage of the immune system is found in the alimentary tract?
70%
140
What things does the epithelium of the alimentary tract have to secrete and absorb?
Secretes:
* Mucus
* HCl
* Hormones
* Enzymes
Absorbs:
* Products of digestion
141
Does intercellular transport occur in the alimentary tract?
Not much, since there are tight junctions between cells.
142
What is immunological protection of the ailmentary tract carried out by?
GALT (gut-associated lymphoid tissue) and other systems
143
Give some examples of diffuse and organised lymphoid structures in the alimentary tract.
144
What are the 4 layers (and sub-layers) of the alimentary tract wall? [IMPORTANT]
From inside to outside:
* Mucosa
* Epithelial lining
* Lamina propria
* Muscularis mucosae (smooth muscle)
* Submucosa
* Connective tissue
* Meissner's nerve plexus
* Muscularis
* Circular internal muscular layer
* Auerbach’s nerve plexus
* Longitudinal external muscular layer
* Serosa
* Connective tissue
145
What are the 3 layers of the mucosa of the alimentary tract?
* Epithelium
* Lamina propria
* Muscularis mucosae (muscle)
146
What is the submucosa of the alimentary tract? What is found in it?
* It is a layer of connective tissue, containing blood and lymph vessels.
* Meissner's nerve plexus is also in this layer.
147
What is the muscularis layer of the alimentary tract? What is found in it?
* It is a layer of muscle
* It also contains Auerbach's plexus
* The plexus is between an inner and outer muscular layer
148
What is the serosa layer of the alimentary tract? What is found in it?
* Connective tissue with mesothelium covering
* Epithelium lining producing lubricating slippery fluid to facilitate movement
149
What are the two plexuses of the myenteric nervous system and where in the wall is each found?
* Meissner’s (submucosal) plexus -\> In the submucosa
* Auerbach’s (myenteric) plexus -\> In the muscularis
150
What does Meissner's (submucosal) plexus govern?
* Secretory function
* Mucosal movement
* Localised blood flow
151
What does Auerbach's (myenteric) plexus govern?
* Outer muscularis muscle layer -\> Responsible for peristaltic activity
152
Are Meissner's and Auerbach's plexuses sympathetic or parasympathetic?
* Meissner's -\> Parasympathetic
* Auerbach's -\> Sympathetic and parasympathetic
153
What type of epithelium is in the oesophagus?
Stratified squamous
154
What does the lamina propria of the oesophagus wall contain?
* Mucus-producing cells with secretory granules -\> Produce mucous to lubricate epithelium to aid passage of food
* Houses GALT system
155
What important cells are found interspersed in the epithelium of the oesophagus? [IMPORTANT]
Langerhans cells
156
What are Langerhans cells and what is their role? [IMPORTANT]
They are dendritic cells involved in antigen presentation.
157
What is found in the submucosa of the oesophagus?
Oesophageal glands proper -\> Mucous and serous cells
158
What do the oesophageal glands (in the submucosa) produce?
Produce:
* Mucus
* Pepsinogen
* Lysozymes
159
Label this image of the oesophagus.
160
What is the name for the thick fluid into which food is processed in the stomach?
Chyme
161
Compare the volume of the stomach at rest and at maximum distension.
* At rest = 50ml
* Max. distension = 1500ml
162
What are the folds on the inside of the stomach called?
Rugae
163
What are the different parts of the stomach?
* Cardiac – Narrow region at gastroesophageal junction
* Fundus – Dome shaped region to left of oesophagus filled with gas
* Body – Largest portion responsible for formation of chyme
* Pylorus – Funnel shaped constricted portion with pyloric sphincter that controls release of food into duodenum
164
What is unusual about the gastric epithelium?
It invaginates into the mucosa.
165
What is another name for gastric pits?
Foveolae
166
How many gastric glands open into each gastric pit (foveolae)?
5-7
167
In what part of the stomach wall are gastric glands?
Lamina propria (in the mucosa)
168
What are the different cell types and functions in the gastric pits? (In order from superficial to deep)
169
What is the function of surface-lining cells in gastric pits?
* Cytoplasm houses secretory granules containing precursor of visible mucus
* Protects stomach from auto digestion
* HCO3- have buffering capacity
* Lateral cell membranes form zona occludens and zona adhernes with neighbouring cells
170
What is the function of mucous cells in gastric pits?
* Surface granules secrete mucus different from surface lining cells -\> Soluble and lubricates gastric contents
* Lubricates epithelium and protects cells from acidic and enzymatic properties of gastric juices
171
What shape are mucous neck cells in the stomach?
Columnar
172
What is the function of regenerative cells in the gastric pits?
Proliferate to replace all of the specialised cells in the stomach.
173
Where are regenerative cells found in gastric pits?
Interspersed among the mucus neck cells in the isthmus of gastric pits.
174
Describe the structural features of regenerative cells in gastric pits.
* Do not have many organelles but have a rich supply of ribosomes
* Basally located nucleus
175
What is another name for parietal cells in gastric pits?
Oxyntic cells
176
What is the function of parietal (oxyntic) cells in gastric pits?
* Manufacture HCl
* Manufacture gastric intrinsic factor (binds vitamin B12)
177
What do parietal (oxyntic) cells produce HCl in response to?
* Histamine
* Parasympathetic activity
* Gastrin
178
Describe the main features of the secretory network of parietal (oxyntic) cells.
* Canaliculi lined by microvilli
* Tubovesicular system
* Mitochondria
179
What is another name for Chief cells in gastric pits?
Zymogenic cells
180
What is the function of Chief (zymogenic) cells in gastric pits?
Manufacture (and house in secretory granules):
* Pepsinogen
* Renin
* Gastric lipase
181
What stimulates pepsinogen release from Chief (zymogenic) cells?
Vagus nerve stimulation
182
Describe the structural features of Chief (zymogenic) cells.
* Have basophilic cytoplasm with basal nucleus and rich RER and extensive Golgi
* Short blunt microvilli
183
What does DNES cells stand for?
Diffuse neuroendocrine cells
184
How many DNES cell types are there?
At least 13
185
What is the function of DNES cells in gastric pits?
Manufacture hormones.
186
How many different agents can a single DNES cell type secrete?
Usually one, but sometimes two.
187
Do all DNES cells reach the lumen of the gut?
* Some do (open) but some do not (closed).
* That is why the cells can be endocrine, paracrine or neurocrine.
188
What is the principle hormone manufactured by DNES cells?
Gastrin -\> Peptide that is important in control of acid secretion and gastric motility.
189
Draw the position of different cell types in gastric pits.
190
How long is the small intestine?
7m
191
What are some different ways in which the surface area of the small intestine is increased?
* Plicae circulares (valves of Kerckring)
* Villi
* Microvilli
* Crypts of Lieberkuhn
192
What are plicae circulares?
Transverse folds of the small intestine that increase its surface area by 2 to 3 times.
193
What is the difference between villi and microvilli?
* Villi
* They are the projections that are made up of multiple cells
* Increase surface area by factor of 10
* Microvilli
* They are the tiny projections on the apical plasmalemma of epithelial cells covering villi
* Increase surface area by factor of 20
194
What are crypts of Lieberkuhn?
* Found in the small intestine and large
* Invaginations of epithelium into lamina propria forming intestinal glands
* Think of them as equivalents of gastric glands, but in the intestine
195
What is the main cell type in the small intestine?
Enterocytes
196
What is the type of epithelium in the small intestine?
Columnar epithelium (ciliated)
197
What is the name for the border of the absorptive epithelium in the small intestine?
Brush border
198
What forms the core of villi?
* Lamina propria
* The epithelium covering of each villi is made up of epithelial cells
199
What are lacteals in the small intestine? [IMPORTANT]
Lymphatic capillaries inside villi that absorb dietary fats.
200
What is found inside villi?
* Core is made of lamina propria
* Capillaries -\> Transport digestive products to hepatic portal vein
* Lacteals -\> Lymphatic vessels that drain into larger vessel (transport lipids)
201
What forms the brush border in the small intestine?
Microvilli
202
Describe the structure of microvilli in the small intestine.
* Do not contain organelles
* Structural core is formed by cross-linked actin filaments
* Structural core is attached to the plasma membrane by myosin and calmodulin
203
What are the different types of cell in the small intestine epithelium and what is the function of each?
* Absorptive cells (enterocytes)
* Tall columnar cells with brush border for terminal digestion and absorption of water and nutrients
* Goblet cells
* Manufacture mucinogen whose hydrated from is mucin -\> Provides protection
* DNES cells – Produce paracrine and endocrine hormones – 1% of cells
* Regenerative cells
* Paneth cells
* Host defence cells
* Manufacture lysozome, defensin, and TNF
204
What is the name for the glands in the duodenum and where in the wall are they found?
* Brunner's glands
* Found in the submucosa
205
What are the Brunner's glands and what is their function?
* Branched tubuloalveolar glands in the submucosa of the duodenum
* Produce:
* Mucous, bicarbonate rich fluid -\> Neutralises acid
* Urogastrone (HEGF) -\> Inhibits production of HCl
206
Label this.
207
Describe the different immune structures in the small intestine.
Ileum has:
* Peyer's patches
* M cells
208
What are Peyer's patches? [IMPORTANT]
* Collections of lymphocytes and antigen-presenting cells (APCs).
* They are found under the epithelium of the small intestine.
209
What are M cells?
* They specialised epithelial cells that are found in the small intestine.
* They perform a surveillance role, looking for antigens.
210
What does the M in M cell stand for?
Microfold
211
How are Peyer's patches and M cells related?
* M cells have basal membrane invaginations that form pits containing Peyer’s patches
* The M cells sample antigens in small intestine lumen and phagocytose them
* The basement membrane under M cells is discontinuous, which allows transport of antigens to antigen presenting cells (APCs) in the Peyer's patch
* These can then present the antigens to lymphocytes in the Peyer's patch
212
What does chronic inflammation of the small intestine result in?
213
What are the main segments of the large intestine?
* Cecum
* Colon
* Rectum
* Anus
214
How long is the large intestine?
1.5m
215
Does the large intestine have villi or folds?
No
216
Are any nutrients absorbed in the large intestine?
No
217
Compare the structure of the wall of the small and large intestine.
218
Are there any pits in the large intestine?
Yes, there are the crypts of Lieberkuhn.
219
How does the number of goblet cells change along the large intestine?
The number increases from cecum to sigmoid colon.
220
How frequently is the epithelial lining of the crypts of Lieberkuhn in the large intestine replaced?
Every 6-7 days
221
What are taniae coli?
Three separate longitudinal ribbons (taeniae meaning ribbon in latin) of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons
222
Describe Crohn's disease.
223
Draw how the histological structure of the GI tract changes along the length.
224
Describe the different levels of the ducts in a digestive gland.
* Acinus
* Intercalated duct
* Interlobular duct
* Lobar duct
* Main duct
225
What are the 3 types of cell in the secretory portion of the salivary glands? What is the function of each?
* Serous cells -\> Secrete proteins and polysaccharides
* Mucous cells -\> Secrete mucous
* Myoepithelial (basket) cells -\> Have several long processes that envelope the acinus
226
Describe the histological structure of the exocrine pancreas.
* Acinar cells secrete enzymes
* Centroacinar cells are duct cells that extend into the acinus -\> They secrete buffer
227
What is the liver surrounded by?
Glisson's capsule
228
How many lobes are in the liver?
4
229
What type of cell are hepatocytes?
Epithelial cells
230
What is the porta hepatis?
The inferior region of the liver where blood vessels enter and leave. The hepatic ducts also leave the liver here.
231
What are the two structural and two functional models of the a liver lobule?
Classical liver lobule model (structural):
* Central vein, seen as single holes
* Peripheral portal triads set at angles to the polygons
* Hepatocytes radiating from the central vein separated by vascular sinusoids
Portal lobule model (structural):
* Portal tracts and triads are at the centre of this model
Acinar model (functional):
* Region irrigated by a single distributing vein
* Based on functional considerations:
* O2 gradients
* Distribution of drugs
* Zones of damage following insult
Primary lobule model (functional):
* This model is based on angioarchitecture and metabolic gradients which are sub-divisions of the classic hepatic lobule.
232
What is a liver lobule?
* Small divisions of the liver defined at the microscopic (histological) scale.
* It consists of a portal triad, hepatocytes arranged in linear cords between a capillary network, and a central vein.
233
What are portal triads in the liver?
* A portal triad is the structure that is found in each corner of a liver lobule
* In it, there are:
* Branches of the hepatic artery
* Tributaries to the hepatic portal vein
* Bile ducts
234
What type of capillary is found in the liver?
Sinusoidal
235
What are sinusoids and spaces of Disse in the liver?
* Sinusoids are sinusoidal capillaries that flow through the liver
* Spaces of Disse are the spaces in between the capillary and the sinusoids
236
How much bile does the liver produce?
600-1200ml/day
237
What is the lifespan of hepatocytes?
150 days
238
What are Kupffer cells and where are they found?
* They are resident macrophages found in the liver.
* They tend to be found lining the sinusoids.
239
Describe the polarity of hepatocytes.
240
What are these cells?
Kupffer cells
241
What are stellate cells involved in?
Response to liver injury
242
Where in the gall bladder are gallstones most frequently lodge?
Hartman’s pouch -\> An outpouching in the neck of the gall bladder.
243
What are the layers of the gall bladder wall?
* Epithelium
* Lamina propria
* Smooth muscle
* Adventitia
244
What is the epithelium in the gall bladder?
Simple columnar epithelium, with microvilli
245
Does the gall bladder have a muscularis mucosa?
No
246
Which layer of the gall bladder wall contains the lymphatics?
Submucosa
247
What is the outer layer of the gall bladder called?
Serosa (it is continuous with the peritoneum
248
How does the wall of the gall bladder compare with that of the different parts of the alimentary tract?
* No muscularis mucosae (this is the thin muscular layer just outside the lamina propria)
* Muscular fibres not arranged in distinct layers
