GI Revision Flashcards
1
Q
What are the abdominal wall layers?
A
Skin Campers fascia (fat) Scarpers fascia (fibrous) External oblique Internal oblique Transverse abdominis Transversalis fascia Parietal peritoneum
2
Q
What level is the coeliac trunk?
A
T12
3
Q
Which organs are secondary retroperitoneal?
A
Pancreas
Duodenum
Colon - asc and desc
4
Q
What is the sympathetic innervation to the gut and its effect?
A
Greater, lesser and least splanchnic nerves
Vasoconstriction
5
Q
What is different about abdominal sympathetics?
A
Do not synapse at the sympathetic trunk
6
Q
What is the PS innervation to the gut and its effect?
A
Vagus n - to 2/3 TC
Pelvic n - to anal canal
Innervate SM, HCl secretion, ACh and GRP.
7
Q
L vagus nerve becomes ______
R vagus nerve becomes _______
A
L - anterior
R - posterior
8
Q
What are the roots of greater, lesser and least splanchnic nerves?
A
T5-9
T10-11
T12
9
Q
What is another name for the submucosal plexus?
A
Meissner’s
10
Q
What is another name for the myenteric plexus?
A
Auerbach’s
11
Q
What are the 2 groups of hormones in the gut?
A
Gastrin - gastrin + CCK
Secretin - secretin + gastrin inhibitory peptide
12
Q
Which cells secrete CCK, where are they, what are they stimulated by?
A
I cells - duodenum + jejunum
Fat and protein in lumen
13
Q
What is the role of secretin?
A
Increases HCO3- from pancreas
Decrease gastric acid secretion
Neutralise chyme
14
Q
What is the effect of gastrin inhibitory peptide?
A
Increase insulin
Decrease gastric acid secretion
15
Q
When might there be gut motility issues?
A
Hirschsprungs disease - no enteric plexus
Paralytic ileus - after surgery
16
Q
Greater omentum is formed from the ________.
A
Dorsal mesentary
17
Q
Lesser omentum is formed from the __________.
A
Ventral mesentery
18
Q
Which organs have a dual blood supply?
A
Pancreas + duodenum - CT and SMA
19
Q
What happens in reversed rotation in midgut development?
A
One rotation clockwise
TC posterior to duodenum
20
Q
What happens in incomplete rotation?
A
only 1 90 degree rotation - left sided colon as caudal limb returns first.
21
Q
What are the risks of midgut defects?
A
Volvulus
SMA compress TC
Subhepatic caecum
22
Q
What is the difference between omphalocoele and gastroschisis?
A
Omphaloceole - incomplete physiological herniation, not isolated condition, amnion covering.
Gastroschisis - failure of abdominal wall, isolated.
Bowel exposed to amniotic fluid.
23
Q
What is formed from ventral mesentery?
A
Lesser omentum
Falciform ligament
24
Q
During midgut development, which limb returns to the cavity first?
A
Cranial
25
What are 3 remnants of the yolk sac?
Vitelline cyst
Vitelline fistula
Meckel's diverticulum
26
What is the anal canal derived from?
Endoderm
| Ectoderm - proctodeum
27
What is the difference between above pectinate line and below pectinate line?
Above - splanchnic innervation, stretch only. columnar ep. IMA.
Below - somatic innervation - pain, temp, touch. Strat squamous. Pudendal A.
28
What are the 4 narrow points of oesophagus?
Junction of oes with pharynx
Aorta crosses
L main bronchus crosses
Through diaphragm
29
What are 5 mechanisms preventing reflex?
- LOS
- Diaphragm surrounds and pinches
- Intra-abdominal oesophagus compressed when intra-abdominal pressure rises
- Acute angle of entry- flap-valve crosses oesophagus
- Mucosal rosette at cardia - folds prevent pressure rise
30
What cells are in gastric pits?
```
Mucous neck cells
Chief cells
Parietal cells
D cells
ECL cells
G cells
```
31
What do chief cells secrete?
Pepsinogen
32
How is HCl secretion inhibited?
pH drops as food leaves stomach
Activates D cells - somatostatin inhibits G cells.
Reduced distention - less vagal stimulation.
33
What are the 3 phase of digestion?
Cephalic
Gastric
Intestinal
34
What happens in the cephalic phase of digestion?
PS stimuli - smelling, tasting, chewing
Vagus nerve stimulates parietal cells -> G cells stimulated.
Slight increase in gastric motility
30% HCl
35
What happens in the gastric phase of digestion?
60% HCl
Distension of stomach stimulates vagus nerve
AA + peptides stimulate G cells
Food buffers pH, removes inhibition of gastrin
36
What are G cells stimulated by?
Peptides and AA in stomach lumen
| Vagus n - GRP and ACh
37
What happens in the intestinal phase of digestion?
10% HCl
Initially - duodenum stretch enhances gastrin secretion
Lipids in lumen stimulate enterogastric reflex - reduces vagal stimulation, inhibits stomach secretion.
Chyme - CCK, secretin and GIP - inhibit stomach secretion.
38
What are the 4 main proteases?
Trypsin
Chymotryrpsin
Elastase
Carboxypeptidase
39
Why is it important for chyme release into duodenum to be controlled?
Mass water influx would can cause hypovolaemia.
| Stomach impermeable to water.
40
What is starch made up of?
Straight chain amylose
| Branched amylopectin
41
Which enzymes digest starch?
Amylase - 1,4 bonds
Isomaltase - 1,6 bonds
Alpha-dextrins - amylopectin into smaller chunks
42
What is sucrose?
glucose and fructose
43
Which monosaccharides can be absorbed?q
Glucose, galactose, fructose
44
How is glucose absorbed across the gut lumen?
SGLT1 apical
| GLUT 2 basolateral = facilitated diffusion
45
How is fructose absorbed from the gut?
GLUT 5
46
Why is a mixture of salt and glucose used for oral rehydration?
Glucose stimulates Na uptake via SGLT1. Water follows Na.
47
What is the main stomach enzyme?
Pepsin
48
What is the master regulator of proteases in small intestine?
Trypsin
49
What is an exopeptidase?
Breaks bonds at the end of polypeptide -> dipeptide or AA
50
What is an endopeptidase?
Breaks bonds in the middle of polypeptide -> smaller polypeptide.
51
How are proteins absorbed?
Na+-AA apical transporters
| Dipeptides + tripeptides by PT1 (peptide transporter 1), broken down into AA by cytosolic peptidases.
52
What stimulates water uptake in large intestine?
Aldosterone stimulates Na channels
53
How is calcium absorbed in the intestine?
Low lumen conc - active transport (facilitated diff)
| High lumen conc - paracellular
54
Why is Vit D important for calcium absorption?
Essential for calbindin synthesis
55
What macroscopic features might you see in coeliac disease?
Absence of intestinal villi
Crypt lengthening
Mucosal damage
56
How can hepatitis cause cholestatic jaundice?
Swollen hepatocytes compress low pressure bile canaliculi and sinusoids -> stasis.
57
What would you see upon investigations with pre-hepatic jaundice?
Dark stools - more stercobilin
Raised serum bilirubin
Raised urine urobilinogen
58
What would you see on investigation of intra-hepatic jaundice?
Raised serum bilirubin
| Conjugated bilirubin in urine - dark
59
What signs are associated with post-hepatic jaundice?
Pruritis
Pale stools
Dark urine
60
What investigation results indicate post-hepatic jaundice?
Raised serum bilirubin
Decrease urinary urobilinogen
Conjugated bilirubin in urine
61
What are the 2 main causes of bile duct obstruction?
Gallstone
| Carcinoma of head of pancreas
62
What markers will be raised in bile duct obstruction?
Alk phos
| Gamma GT
63
What is cholangitis, what is it usually caused by?
Infection in common bile duct.
Complication of obstruction.
E.Coli
64
What is charcot's triad?
Fever, RUQ pain, jaundice = cholangitis
65
What is acute cholecystitis?
Infection within gallbladder - complication of cystic duct obstruction.
NOT colicky pain
66
What are the 2 causes of pancreatitis?
Gallstones
| Alcohol
67
What is used to diagnose pancreatitis?
Raised amylase and lipase
68
What are the branches of SMA?
```
Jejunal
Ileal
Ileocolic
Right colic
Middle colic
```
69
What are the branches of IMA?
Left colic - anastomoses with middle colic to form marginal.
Sigmoid branches
Rectal branches (once superior rectal a)
70
What consequence of chronic reflux disease will commonly cause dysphagia?
Fibrous strictures
71
What type of chronic gastritis can lead to a megaloblastic anaemia?
Chronic autoimmune gastritis - antibodies that attack parietal cells. Pernicious anaemia.
72
How does the structure of the large intestine differ to the small intestine?
```
No villi
No plicae circulares
Shorter
Wider
Smoother appearance
```
73
What are 2 functions of the large intestine?
Vit K synthesis by bacteria
| Water reabsorption
74
How is the longitudinal muscle different in the large intestine?
Incomplete - forms 3 bands called teniae coli
Teniae coli contracting form hausfrau.
Appendices epiploicae - fat appendages.
75
How is water reabsorbed in the large intestine?
ENaC - induced by aldosterone
| Tight junctions prevent water loss
76
What extra-intestinal problems are associated with IBD?
MSK pain - arthritis
Skin - erythema nodosum, psoriasis
Eye problems
Primary sclerosing cholangitis
77
Which IBD is smoking associated with?
Crohns
78
What are some causes of IBD?
```
Genetic
Gut organisms
Antibiotics
Infections
Diet
```
79
What is 'lead pipe colon'?
Loss of haustra
| Suggests UC
80
Crohn's pain is most likely to present in which abdominal region?
RLQ - ileum
81
What gross pathology is associated with crohn's?
```
Hyperaemia - red, inflamed
Mucosal oedema - cobblestone
Scar tissue - thickened wall, narrowed lumen
Fistulae
Transmural inflammation
```
82
Name a microscopic feature of Crohn's?
Granuloma
83
What might you find in blood results from patients with IBD?
Anaemia
84
What gross pathology is visible in UC?
Crypt abscesses and distortion
Pseudopolyps
Loss of haustra
85
What is the underlying cause of UC?
Inflammatory infiltrate within lamina propria.
| Superficial mucosal inflammation.
86
UC or Crohns: LI only.
UC - no malnutrition.
87
How do the patterns of UC and Crohn's differ?
Crohns - discontinuous skip lesions
| US - continuous
88
Name 4 types of perianal disease associated with Crohns.
Fistula
Perianal fissure
Haemorrhoids
Skin tag
89
Fibrosis and narrowing occurs in Crohns or UC?
Crohns - scar tissue formation
90
What are 3 causes of bleeding into the gut?
Oesophageal varices
Peptic ulcer
Diverticular disease
91
What signs might you see if there is bleeding into the gut?
Malaena
| Haematemesis
92
How can urea levels indicate the location of a GI bleed?
If upper GI bleed, protein meal to small intestine leads to increased urea levels while creatinine will remain normal.\
93
Name 2 causes of retroperitoneal bleeding.
Ruptured AAA
| Retroperitoneal veins - if on anti-coagulants
94
Name 2 causes of bleeding into the peritoneum?
Ectopic pregnancy
| Perforated viscus - peptic ulcer or diverticular disease
95
How does a perforated peptic ulcer differ in severity to perforated diverticular disease?
Peptic ulcer - gastric contents cause chemical peritonitis
| Diveritular - bacteria and faeces cause peritoneal sepsis.
96
What is the danger of bowel obstruction.
Hypovolaemia and dehydration- accumulation of fluid, decreased reabsorption.
97
Why might acute pancreatitis cause dehydration?
Accumulation of fluid in retroperitoneum
98
What are red flags for GI cancer?
```
Anaemia
Loss of weight
Anorexia
Recent onset progressive symptoms
Malaena + malaise
```
99
Name some differentials for epigastric pain.
Peptic ulcer
Oesophagitis
Pancreatitis
Gastric adenocarcinoma
100
Where is gastric adenocarcinoma usually found?
Cardia or antrum
101
RF for gastric cancer?
Smoking
High salt diet
FH
102
What are 3 types of gastric cancer.
1. Adenocarcinoma
2. Gastric lymphoma - H.pylori treatment regresses
3. GI stromal tumours
103
Which malignancies commonly spread to liver?
colon, gastric, oesophageal, breast, prostate
104
What is courvoisier's law?
Jaundice with enlarged, palpable, non-tender cause is not gallstones.
105
What is tenesmus and what is it a sign for?
Feeling of incomplete emptying
| Rectal cancer
106
What are 2 common causes of anal bleeding?
Haemorrhoids
| Anal fissures
107
RF for colon adenocarcinoma?
Family History
IBD
Polyposis syndrome - FAP
Diet
108
What is the adeno-carcinoma sequence?
Benign polyp - polyp grows - dysplasia - adenocarcinoma in situ - invasive adenocarcinoma
109
Which sided colon cancers usually present first, why ?
Left - smaller lumen with more solid contents leads to obstruction.
Ride side more distensible so obstructive presentation less likely.
110
Which marker is used for bowel cancers?
CEA
111
What are 5 types of small bowel cancer?
```
Adenocarcinoma
Stromal
Lymphoma
Sarcoma
Carcinoid
```
112
How can you identify GI bacterial infections?
Stool culture
| MacConkey agar for salmonella
113
How does shigella invade large intestine cells?
Plasmid encoded virulence genes - lead to endocytosis
| MUCOSA only - no bacteraemia as rarely goes deep.
114
Which GI infection causes 'currant jelly' stools?
Shigella - mucous and blood
115
How does shigella cause diarrhoea?
1. Enters LI and rectal cells by endocytosis.
2. Escapes endocytic vesicles and invades cell
3. Invades neighbouring cells
4. Mucosal abscess as cells die
116
What is a bacterial cause of gastroenteritis?
Salmonella
117
What is the pathogenesis of salmonella?
Invade epithelial cells of small intestine
118
What is a viral cause of gastroenteritis?
Norovirus - winter vomiting bug
119
What does campylobacter look like on gram stain?
Gram negative - pink, seagull appearance
120
What is the most common source of campylobacter infections?
Uncooked poultry
121
What are complications of campylobacter infection?
Early - cholecystitis, rash, peritonitis
| Late - gullain-barre syndrome, reactive arthritis
122
What surface landmark can be used to locate the deep ring?
Midpoint inguinal ligament - half way ASIS to pubic tubercle.
123
What is the most common cause of bowel obstruction?
Hernia
124
Where does the hepatitc portal vein originate from?
Behind the neck of pancreas - confluence of splenic and superior mesenteric veins.
125
Which type of hernia affects young infants and usually spontaneously resolves in the first few years?
Umbilical
126
Where does the linea alba attach from and to?
Xiphoid process to public symphysis
127
Which structure divides the greater sac into supracolic and infracolic compartments?
Transverse mesocolon
128
Which structure lies around the oesophageal hiatus to help prevent reflux?
Right crus of diaphragm
129
What structure passes through the central tendon of the diaphragm?
IVC
130
What type of hernia might be precipitated by a weakened conjoint tendon?
Direct Inguinal Hernia
| Conjoint tendon reinforces medial part of posterior wall, behind superficial inguinal ring.
131
What is the difference between a strangulated and an incarcerated hernia?
Strangulated - compromised blood supply
| Incarcerated - irreducible/stuck
132
What forms the anterior boundary of the lesser sac?
Posterior stomach
| Lesser omentum
133
What forms the posterior boundary of the lesser sac?
Diaphragm
| Pancreas
134
What provides the liver with the greatest structural support within the abdominal cavity?
IVC
135
How does H.pylori cause chronic gastritis?
Degrades mucus layer
| Releases cytotoxins
136
In pancreatic secretions, what happens to the concentration of HCO3- if flow rates increase?
More HCO3- as flow increases
