GI Flashcards
In which section of the GI tract is the appendix located?
Caecum
What is the major function of the colon?
Water absorption- although most already absorbed by SI
Longest section of GI tract?
ileum
Where in the GI tract are the majority of enzymes released?
From pancreas into duodenum
Where do parasympathetic pre-ganglionic fibres synapse in the gut?
Visceral wall
Cranio-sacral outflow refers to which part of the nerve supply to the gut?
Parasympathetic nervous system
What anatomical structure lies at the midpoint of the inguinal ligament?
Deep inguinal ring
What course does a DIRECT inguinal hernia take as it leaves the abdomen?
Passes through a weakness in Hesselbach’s triangle
What is the location of the linea alba?
Vertical in midline from xyphoid process to pubic symphysis
Posterior surface of rectus abdominus muscles are in contact with what structure below the arcuate line?
Transversalis fascia
What type of hernia can be precipitated by a weakened conjoint tendon?
Direct inguinal hernia
Which part of the developing gut tube has a ventral mesentry?
Foregut
How does the stomach physically disrupt food?
Muscular contractions of the ANTRUM
Which gastric secretion is part of the innate immune system?
HCl
Give a hormone involved in paracrine control of gastric acid secretions
Histamine
What causes the ‘alkaline tide’ following a meal?
Movement of HCO3 across basolateral membrane
How do NSAIDs promote epithelial damage?
Reduce gastric prostaglandin synthesis
Name an organ with blood supply from midgut and foregut
Pancreas
Which fold of peritoneum connects liver to stomach?
Lesser Omentum
What happens to bicarb conc in greater flow rates of saliva?
Increases
What consequence of chronic reflux diseases causes dysphagia?
Formation of fibrous strictures in lower oesophagus
What type of chronic gastritis can cause megaloblastic anaemia?
Autoimmune
How does H-Pylori survive acidic conditions of stomach?
Produces urease- converts urea in stomach into ammonia and CO2- ammonia forms a basic solution that raises the pH around the bacteria
What is the pain associated with gallstones called?
Biliary colic
- gallbladder has to contract harder to release bile, pain comes from contraction against stone
- not a true colic as pain does not disappear between contractions
Why does pain from gallstones come on about an hour after eating?
This is the time it takes for ingested material to be released by the stomach into the duodenum (1).
• In the duodenum the presence of acid, amino acids and fatty acids stimulates the release of cholecystokinin (1)
• Cholecystokinin then stimulates gallbladder contraction which causes pain (1) (contracting against a
blockage)
Several weeks after gallstone presentation- worsening abdominal pain, fever and RUQ tenderness. What is the explanation?
A gallstone has now probably lodged in her cystic duct and is causing cholecystitis.
The walls of the gallbladder are inflamed and oedematous and secondary infection can also occur due to bacterial proliferation.
State the potential complications of a stone lodging in:
i) Proximal CBD (2x marks
(ii) Distal CBD (2x marks)
(i)
• Cholangitis (infection of the biliary tree). (1)
• Post hepatic jaundice (can occur due to blockage bile
flow from the Liver/gallbladder to the duodenum). (1)
(ii) • Acute pancreatitis (1) (A stone lodging near the sphincter of oddi can block the major pancreatic duct. This can damage the pancreatic acinar cells due to an increased back pressure.
• Post hepatic jaundice (can occur due to
blockage bile flow from the
Liver/gallbladder to the duodenum). (1)
Following chronic alcohol intake the liver can enlarge (hepatomegaly).
(i) Name the underlying change that has caused liver enlargement
(ii) briefly describe two mechanisms that lead to the process you have named in (i)
(i) Steatosis
(ii) A byproduct of alcohol metabolism is NADH which inhibits lipid breakdown (and/or promotes lipid synthesis)
• Ethanol inhibits the formation and secretion of lipoproteins (so lipids accumulate in the liver)
Briefly describe why chronic alcohol misuse can lead to malnutrition and vitamin deficiencies
• Alcohol related chronic gastritis (impaired
digestion/release of IF)
• Pancreatitis (impaired release of digestive enzymes)
• Intestinal mucosal damage (impaired
absorption/digestion)
• Intake of alcohol replacing calories from diet
An alcoholic patient undergoes an emergency endoscopy which visualises oesophageal varices - an example of a porto-systemic anastomosis.
Briefly explain the most likely processes that have led to the formation of oesophageal varices in this patient
• Chronic alcohol abuse has led to cirrhosis (fibrotic
liver changes)
• Cirrhosis has led to portal hypertension (as portal
vein drains through liver)
• Portal hypertension has created a back pressure on
veins draining through liver, including oesophageal
veins
• Oesophageal veins form the portal section of the
porto-systemic anastomosis in the oesophagus
responsible for varices
Give areas of the body where porto-systemic anastomoses exist other than oesophageal varices
- (upper) Anal canal
• Umbilical region (forms the so called caput medusa appearance)
• Bare area of liver
• Retoperitoneum
Describe features of Crohn’s disease that could be visualised during a colonoscopy?
- Hyperaemia and oedema of the mucosa
- Discontinuous pattern of inflammation (skip lesions)
- Cobblestone appearance (linear ulcers crossing each other with areas of normal or oedematous issue in between, giving a cobblestone appearance).
- Strictures (narrowing of the bowel lumen)
- The openings of fistulae
What microscopic finding is pathognomonic (very characteristic) of Crohn’s disease?
• The presence of epithelioid granulomas
Describe three perianal pathologies that might be present in Crohn’s disease
Anal fistula
Anal fissure
Anal absess
Explain why the right lower quadrant is a common site for abdominal pain and tenderness in Crohn’s disease?
The most common site of involvement in Crohn’s disease is the ileo-caecal region, this is in the right lower quadrant of the abdomen
Explain why weight loss can occur in Crohn’s disease
Crohn’s disease commonly affects the small intestine which is the site of nutrient absorption in the gut .
Inflammatory processes in the small intestine will reduce absorption of nutrients which will (over time) result in weight loss
Briefly describe where bilirubin originates from
Bilirubin is released when red blood cells are destroyed by the reticuloendothelial system
Briefly describe the role the liver plays in processing and excreting bilirubin
The liver conjugates bilirubin to make it soluble then excretes bilirubin as a component in bile
In pre-hepatic jaundice the raised plasma bilirubin levels tend to be unconjugated despite normal liver function.
Briefly explain why (3x marks)
- Pre-hepatic jaundice is caused by conditions that shorten the lifespan or increase the rate of breakdown of red blood cells (1x mark).
- This increases the levels of bilirubin reaching the liver beyond its ability to conjugate and process the bilirubin (1xmark)
- The resulting hyperbilirubinaemia is therefore mostly unconjugated (despite a normally operating liver) (1x mark)
In post hepatic jaundice patients will often notice they have dark urine
Explain why this occurs
In post-hepatic jaundice the liver is able to
process the conjugation of bilirubin so bilirubin is soluble
• However there is a blockage of flow of bile
into the gut so plasma (conjugated) bilirubin levels rise.
• As the bilirubin is soluble it can be excreted
by the kidneys and the bilirubin
gives the urine a dark colour
What liver function test (LFT) when raised is indicative of post-hepatic jaundice?
Alkaline phosphatase (ALP)
Common extra intestinal presentation of IBD?
Arthritis
Where in the oesophagus do you get adenocarcinomas?
Lower third- Barrett’s
Where in the colon would a cancer most likely be that would give you an obstruction?
Sigmoid colon - contents of colon more solid here
Why do you get pain in right iliac fossa with appendicitis?
Inflamed appendix irritates parietal peritoneum
Cause of pseudomembranous colitis ( the yellow plaque thing)?
C diff
Norovirus v rotavirus
Norovirus affects adults as well as children because there are so many strains it is hard to develop immunity. Both require a small dose to spread and last <1 week
Parasitic infection that gives persistent diarrhoea?
Giardia
Severe abdo pain w onset 30 mins after eating that is disproportionate to clinical signs? Who is predisposed to this?
Acute mesenteric ischaemia (more blood supply needed after a meal
More common in the elderly
Anterior boundary of lesser sac is partially formed by…?
Posterior surface of stomach
What divides the greater sac into the supracolic and infracolic compartments?
transverse mesocolon
What structure lies around the oesophageal hiatus that prevents reflux?
Right crus of diaphragm
The hepatic portal vein originates behind which part of the pancreas?
Neck
What type of hernia is precipitated by a weakened conjoint tendon?
Direct inguinal hernia - the CT reinforces the posterior wall of the inguinal canal behind the superficial inguinal ring
How can you treat oesophageal varices that don’t respond to medication/ banding? (check with iz)
TIPS procedure (Transjugular Intrahepatic Portosystemic Shunt) - a stent is put in the liver to create a shunt between the portal vein and the hepatic vein
Cause of primary peritonitis?
Ascites- fluid is a breeding ground for bacteria
What are the branches of the IMA?
Left colic artery- supplies descending colon up to watershed
Sigmoidal artery- supplies sigmoid colon
Superior rectal artery- supplies superior rectum
What are the branches of the SMA?
Ileocaecal artery- supply starts at the IC valve, does ileum, caecum and appendix
Right colic- supplies the ascending colon
Marginal artery- supplies the transverse colon
A 57-year-old man present to the Emergency department with abdominal pain and vomiting. He has a PMH of a groin hernia, which has been reducible until a week ago.
On examination there is a firm lump found in the right inguinal region which is tender on palpation.
Briefly explain how this firm lump could be related to his current presentation
Firm lump is most likely to be an incarcerated hernia.
• If the hernia contains small bowel, then this might be causing bowel obstruction.
• Small bowel obstruction will result in abdominal pain and vomiting in its early stages.
Difference between strangulated and incarcerated hernias?
Incarcerated means stuck (not able to reduce)
Strangulated relates to a compromised blood supply
Borders of Hesselbach’s triangle?
(Inferior) – Inguinal ligament
• (Superolateral) -Inferior epigastric vessels (artery and vein)
• (Medial)- (lateral border of) rectus abdominus muscle
Briefly explain/define Secondary peritonitis
Results from an inflammatory process
• in the peritoneal cavity
• As a result of (Secondary to) inflammation, perforation, or gangrene of an intra-abdominal or retroperitoneal structure
Common causes of secondary bacterial
peritonitis include…
Peptic ulcer disease (perforated)
• Appendicitis (perforated)
• Diverticulitis (perforated)
• Post surgery
What underlying pathological process must be present in a patient for primary peritonitis to form? What pt group is this seen in? Diagnosis?
Ascites
Most commonly seen in patients with end stage liver
disease (patients with cirrhosis)
Diagnosed by aspirating ascitic fluid- neutrophil count
>250 cells/mm³
Pt recounts passing a small amount of bright red blood when defaecating which has been accompanied by peri-anal itching. Diagnosis? Why is it painless?
Internal haemorrhoids
• They originate from above the dentate line in the anal canal.
• This is hindgut epithelia and does not have a somatic sensation /pain receptors
Function of anal cushions?
To support anal/faecal continence
a. What is an anal fissure?
b. State one predisposing factor for developing an anal fissure
a) A tear in the anoderm (epithelia of the anal canal)
b) High internal anal sphincter tone/Reduced blood flow to anal mucosa
are anal fissures painful?
Yes like passing razorblades
State 2 relatively common pathologies other than haemorrhoids that could cause rectal bleeding in a young patient
Ulcerative colitis
• Crohn’s disease
• Angiodysplasia in the colon
Briefly describe why bleeding from a more proximal
location in the gut does not result in bright red blood being passed?
The blood is acted on by enzymes/ is digested
As a result, it appears black in colour
What ventral wall defect have the gut contents herniated through in an omphalocoele?
Umbilical ring
What structure forms the axis of rotation for the midgut during its herniation?
SMA
What is the developmental problem underlying gastroschisis?
Incomplete lateral folding
Why are the intestines in gastroschisis often underdeveloped compared to the intestines in an
Omphalocoele?
The intestines are not covered in a peritoneal covering in gastroschisis whereas they are in an Omphalocoele
This means they are exposed to amniotic fluid which slows down their development
Which muscle of the anterior abdominal wall, when contracted, causes ipsilateral (same side) rotation?
Internal oblique
What developmental defect can occur If the Vitelline duct fails to regress (at all) ? accompanying clincial sign?
Vitelline fistula formation
Faeces leaking out of the umbilicus
What forms the lateral border of the femoral ring?
Femoral vein - NAVEL
What structure lies at the mid point of the inguinal ligament?
Deep inguinal ring
Feeling that you need to pass stool even though your bowels are empty?
Tenesmus
