1 Flashcards
Why does cholecystitis cause shoulder pain?
This is referred pain.
the phrenic nerve gives sensory fibres to the adjacent diaphragm, and potentially the gallbladder. Many of the fibres in the phrenic nerve come from the C4 spinal nerve, which is also sensory to the shoulder
Explain the hormonal control of gallbladder contraction
cholecystokinin is released in response to the entry of fatty acidic chyme into the duodenum. CCK stimulates gall bladder contraction and relaxation of the sphincter of oddi
Blood results:
1) +++ elevated ALP
2) elevated ALT
3) ++ Bilirubin
4) ++ conjugated bilirubin
Explain the diagnosis and reasoning behind it.
This is a case of post-hepatic obstructive jaundice.
Bilirubin is mainly conjugated in the liver. The high levels of conjugated bilirubin indicate that it must have passed through the liver.
ALP is produced by the epithelial lining of the bile ducts. Elevated ALP therefore suggests obstruction of these ducts.
Jaundice
reflects elevated serum bilirubin levels.
usually clinically evident when greater than twice the normal level
Which cell organelle is responsible for the conjugation of bilirubin?
the endoplasmic reticulum
Into which lumen is conjugated bilirubin directly secreted by hepatocytes?
bile canaliculus
Which vein carries resorbed urobilinogen from the terminal ileum to the portal vein?
superior mesenteric vein
What does ERCP stand for
endoscopic retrograde cholangiopancreatography
functions of cholesterol
steroid hormone precursor
component of cell membranes
precursor of bile acids
component of plasma lipoproteins
explain how statins work
statins competitively inhibit the action of HMG-CoA reductase, decreasing hepatic cholesterol synthesis
They also induce LDL receptor expression, and therefore enhance cholesterol clearance by the liver
Name four organisms that commonly cause bloody diarrhoea
1) campylobacter
2) salmonella
3) E. coli
4) Shigella
Also entamoeba histolytica
Where is CRP produced?
Hepatocytes
What is the clinical significance of elevated CRP?
Nonspecific indicator of inflammation or infection in the body
CRP is an acute phase reactant protein
What would you test for in anaemic patients?
Serum ferritin, folate, B12 and iron
why would a patient have low iron levels and high serum ferritin levels?
Ferritin production is usually down-regulated when iron levels are low.
Elevated serum ferritin is possible with low iron because it is an acute phase reactant protein produced by the liver, and is elevated with inflammation/illness
In what ionic form is iron most commonly ingested, ferric or ferrous?
Most is ingested in the ferric form (Fe3+)
Ferrous iron = Fe2+
What ionic form of iron is absorbed in the GI tract?
Ferrous iron = Fe2+
Fe3+ is converted to Fe2+ by enzymes on the brush border or enterocytes = duodenal cytochrome b1
Where in the GIT does iron absorption occur?
Duodenum
How is iron transported into cells and what is its fate after this?
Fe2+ is transported into the enterocyte through DVMT 1 (divalent metal transporter 1)
It can then either be stored in the enterocyte as ferritin if body iron stores are high, or it can be transported out of the cell by ferroportin, a transported in the basolateral membrane
In plasma, Fe2+ is converted back to Fe3+, which binds to transferrin. It is then carried to sites such as the liver, bone marrow, and spleen
List the 4 main histological layers of the colon
1) mucosa
2) submucosa
3) muscularis externa
4) serosa
Where would you find auerbach’s plexus
= the myenteric plexus
between the circular and longitudinal layers of the muscularis externa
Describe the overall innervation of the intestine
innervated by the autonomic nervous system.
Parasympathetic cholinergic activity increases the activity of intestinal smooth muscle.
Sympathetic noradrenergic activity decreases the activity of intestinal smooth muscle, and causes sphincters to contract.
Parasympathetic fibres terminate on postganglionic neurons of the submucosal and myenteric plexuses
Sympathetic fibres are postganglionic neurons,. and end directly on smooth muscle cells
Which structures of the colon are retroperitoneal?
ascending colon
descending colon
rectum
Name retroperitoneal structures
adrenal glands kidneys ureters pancreas (except tail) IVC Aorta duodenum (partially) oesophagus (partially)
What is the blood supply of the ascending colon?
SMA = right colic artery and ileocolic artery
What is the commonest site of crohn’s disease?
terminal ileum
What are they symptoms of Crohn’s?
abdominal pain
malabsorption
weight loss
diarrhoea and bleeding if the colon is involved
Macrocsopically - cobblestone appearance (deep ulcers and fissures)
What are they symptoms of UC?
Diarrhoea with blood and mucous
Macroscopically the mucosa appears red and bleeds easily
Ulcers and pseudopolyps may be visible
disease process is continuous throughout the colon and rectum
Which colonic pathology can develop in patients who have longstanding IBD, especially UC?
colonic cancer/colonic adenocarcinoma
What is the surface marking of the fundus of the gallbladder?
Where the right side of the rectus abdominis muscle meets the costal margin (tip of 9th costal cartilage - although this is difficult to distinguish in clinical practice()
In surgery, what is Courvoisier’s law?
states that painless jaundice and a palpable gallbladder are rarely due to gallstones, but due to a tumour or other pathology
What causes itch in obstructive jaundice?
deposition of bile salts in the skin
How can you treat itch in obstructive jaundice?
cholestyramine
this is an anion exchange resin that binds to bile salts in the small intestine and blocks reabsorption, preventing enterohepatic recirculation
What do anion exchange resins do?
inhibit enterohepatic recirculation of bile salts
This indirectly lowers LDL cholesterol levels in the blood by increasing hepatic synthesis of bile acids, increasing LDL surface receptors as LDL is required for this.
Can be used in addition to statins
What would you expect to happen to albumin levels with obstructive jaundice?
decreased due to reduced synthetic function of the liver.
Albumin is only synthesised in the liver
What would you expect to happen to prothrombin time with obstructive jaundice?
increased
the liver is the site of clotting factor synthesis, and alll clotting factors except factor VIII are made in the lvier.
Vitamin K-dependent factors (II, VII, IX and X) may be deficient due to malabsorption of vitamin K
What is prothrombin time ?
predominantly a measure of the extrinsic clotting cascade
may be prolonged due to causes other than liver malfunction, e.g. vitamin K deficiency and warfarin therapy.
Which substances formed from bile pigments give stool its characteristic colour?
urobilinogen
stercobilinogen
What biochemical abnormalities are seen in the urine with obstructive jaundice?
low/absent urobilinogen
high urinary bilirubin (darkened urine)
Which region of the peritoneal cavity is the pancreas related to?
the lesser sac (omental bursa)
How is a pancreatic mass most likely to cause jaundice?
obstruction of the common bile duct, which runs posterior to or is embedded within the head of the pancreas
What is a common complication of ERCP?
acute pancreatitis
Which borders of the spleen contain notches?
anterior and superior
Which border of the spleen is palpable with splenomegaly?
superior border
moves inferomedially
What is a porto-systemic anastomosis
connection between the veins of the portal venous system, and the veins of the systemic venous system
What are the major sites of porto-systemic anastomoses
Oesophageal – Between the oesophageal branch of the left gastric vein and the oesophageal tributaries
to the azygous system.
o oesophageal varices
Rectal – Between the superior rectal vein and the inferior rectal veins.
o Haemorrhoids
Retroperitoneal – Between the portal tributaries of the mesenteric veins and the retroperitoneal veins.
Paraumbilical – Between the portal veins of the liver and the veins of the anterior abdominal wall.
o caput medusa
arterial supply of the duodenum
Proximal to the major duodenal papilla– gastroduodenal artery(branch of thecoeliac trunk).
Distal to the major duodenal papilla– inferior pancreaticoduodenal artery(branch ofsuperior mesenteric artery).
Meckel’s diverticulum
a slight bulge in thesmall intestine present at birth and avestigial remnant of the yolk stalk
how is the duodenum distinguished from jejunum and ileum histologically?
presence of brunner’s glands
Paneth cells
Found at the base of intestinal crypts
distinguished by their granular cytoplasm
Secrete granules of antimicrobial peptides called defensins, lysozyme and phospholipase A
not found in the large intestine
Which part of the intestine has the longest villi?
villi tend to be longest in the duodenum and shortest in the ileum
Which part of the small intestine has the most lymphoid tissue?
ileum
How does acute pancreatitis cause back pain?
the pancreas is a retroperitoneal organ
leakage of inflammatory exudate therefore leaks into the retroperitoneal space and lesser sac.
this causes irritation of reroperitoneal and pertioneal nerve endings
this produces intense back pain
Cullen’s sign
umbilical discolouration (bluish) seen in acute pancreatitis and ruptured ectopic pregnancy
Grey Turner’s sign
blue discolouration of the flank
seen in acute pancreatitis
Explain how the pancreolauryl test works
Fluorescein dilaurate is administered orally. This is poorly absorbed in the gut.
Pancreatic elastase converts Fluorescein dilaurate to fluorescein, which is readily absorbed by the gut
Once absorbed, Fluorescein is excreted in the urine. The presence of Fluorescein in the urine is therefore a marker of pancreatic function.
Define ascites
accumulation of free fluid in the peritoneal cavity
Name 3 conditions that can cause ascites
1) chronic liver disease
2) chronic heart disease
3) abdominal malignancy
Explain the pathophysiology of gynacomastia
occurs due to increased oestrogen levels
results from decreased clearance of endogenous oestrogen by the diseased liver
Why does splenomegaly occur with portal hypertension?
splenic vein is a tributary vein of the portal vein
there are no valves in the portal venous system, therefore portal HTN causes the spleen to become congested and enlarged due to backflow of blood
Describe the location of the spleen
left hypochondrium
at the level of 9th-11th ribs
posterior to the midaxillary line
separated from the left lung by the diaphragm, covered superiorly by pleural and inferiorly by peritoneum
Where are the portal tracts situated?
at the corners of classical liver lobules
Name the three tubular structures found in the portal tract
Branches of:
- hepatic artery
- hepatic portal vein
- bile ductule
portal tracts also contain lymphatics
Give two ways in which the cellular lining of the liver sinusoids is specialised to aid liver function.
1) endothelium is fenestrated to enhance permeability
2) Kupffer cells lie in the endothelial layer. These are phagocytic
- remove aged and damaged RBC, bacteria and antigen-ab complexes from circulation
- derived from circulating monocytes
What is the perisinusoidal space of Disse and what function does it assist?
region between hepatocytes and the sinusoid lining
contains microvilli from non-canalicular surfaces of hepatocytes
increases the surface between hepatocytes and passing fluid, facilitating exchange between blood/hepatocytes
What substance is produced in the first step of alcohol metabolism catalysed by cytoplasmic alcohol dehydrogenase?
acetaldehyde
is the cytoplasmic alcohol dehydrogenase pathway inducible?
no
Describe the ratio of AST:ALT in alcoholic liver damage
often >2
What does markedly elevated gamma glutamyltransferase suggest?
alcohol-related disease
What does markedly elevated ALP suggest? (if hepatic in origin)
obstruction of bile ductules due to inflammation of liver parenchyma
With liver disease, what are likely explanations for macrocytic anaemia?
1) alcohol - has a suppressant effect on bone marrow
2) folic acid deficiency
What are 4 characteristic histological features of alcoholic hepatitis?
1) macrovesicular fat globules (presence of fatty change)
2) mallory bodies (alcoholic hyaline)
3) hepatocyte ballooning/necrosis
4) Neutrophil infiltrate
Early deposition of fibrous tissue may also be seen
Define cirrhosis
Diffuse process where repeated hepatocyte destruction is followed by regeneration to replace lost cells
There is also deposition of collagenous tissue
The combination of fibrous scarring and nodular regeneration of hepatocytes = cirrhosis
Describe the two types of cirrhosis
1) micronodular - uniform small nodules (>3mm). Commonly seen in alcoholic cirrhosis
2) macronodular - larger nodules (up to 2cm diameter). Often seen with chronic hep B infection
A mixture is also possible
Where does the pharynx become continuous with the oesophagus?
C6
lower limit of the larynx - cricoid cartilage
In which regions of the mediastinum does the oesophagus lie?
superior and posterior
where does the oesophagus enter the abdominal cavity
passes through the right crus of the diaphragm, slightly to the left of the midline at the level of T10
What anatomical and physiological arrangements protect against GERD?
1) Lower oesophageal sphincter
2) angle between lower oesophagus and the fundus of the stomach
3) mucosal rosette formed by folds of mucosa at the GE junction
4) crura of the diaphragm surrounding the oesophagus
5) oesophageal peristalsis
6) gastric peristalsis
What factors predispose to GERD?
1) defective LES function - smoking, fatty meals, delayed gastric emptying, following sphincter surgery for achalasia
2) increased intra-abdominal pressure - tight fitting clothes, obesity, large meals, pregnancy, ascites, abdominal mass
3) drugs - TCAs and anticholinergics
What is a hiatus hernia?
condition where the upper part of the stomach protrudes through the diaphragm into the abdominal cavity
Describe the difference between a sliding hiatus hernia and a rolling hiatus hernia
sliding - gastro-oesophageal junction slides up into the chest
rolling - fundus of the stomach protrudes into the thoracic cavity alongside the oesophagus, usually to its left
What type of cell is found on the mucosal surface of the stomach lumen?
Surface mucous cells
NB: in these cells the mucous does not form goblets
Why is intrinsic factor important?
Binds to vitamin B12 and allows absorption in the ileum
Describe the mechanism of acid secretion in the stomach
Parietal cells are rich in carbonic anhydrase
Catalyses reaction of CO2 + H2O -> H+ and HCO3-
H+ is pumped into the lumen of the stomach via primary H/K-ATPases at the luminal membrane
HCOO3- is secreted at the basolateral membrane in exchange for chloride ions
acid is released into the intracellular canaliculus of the parietal cell
Name 4 mediators that augment gastric acid secretion
1) ACh
2) Gastrin
3) Histamine
4) Somatostatin
What is metaplasia?
change in cells from one type to another
What is the clinical significance of Barret’s oesophagus?
pre-cancerous lesion - increases the risk of oesophageal cancer
Name 3 drugs that can be used to treat GERD and their mechanism of action
1) antacids - aluminium hydroxide/magnesium carbonate
2) alginates - gaviscon
3) PPIs - omeprazole
4) H2R antagonists - cimetidine
5) metoclopramide = prokinetic. May improve GE sphincter function and accellerate gastric emptying
Clinical signs and symptoms of dehydrations
Hypotension tachycardia dry mouth decreased skin turgor decreased jugular venous pressure
What is the average daily insensible loss?
800 ml
For IV rehydration, how do you calculate the fluid required?
Fluid required = ML + IL + PDD
How can on large doses of broad spectrum
antibiotics cause diarrhoea?
Antibiotics may kill some commensal bacteria
Can impact colonic water reabsorption due to decreased fermentation of SCFA. This causes osmotic diarrhoea
Increases the risk of pathogenic bacteria becoming established within the gut (e.g. C. difficile)
What are the main beneficial metabolic activities of the normal colonic microbiota?
1) fermentation of indigestible carbohydrates (notably cellulose) and lipids to produce SCFA
- helps with water reabsorption
- salvages energy from products that havent been digested
2) synthesise vitamin K
3) bacteria release bactericides, which target pathogenic bacteria, preventing infection
Describe the types of Enteric Bacterial toxins
1) Neurotoxins - act very peripherally and interfere with gastric motility. Cause vomiting illness with very short incubation period
2) Secretory enterotoxins - Causes watery diarrhoea, but patient is often systemically quite well
3) Cytotoxins - Cause direct damage to the cells or cause cells to undergo apoptosis
Gall Bladder relaxation and closure of Sphincter of Oddi is mediated by
Vasoactive Intestinal polypeptide (VIP)
Deficiency of pancreatic proteases can result in
increased risk of infection
Which nerve supplies the internal anal sphincter?
Hypogastric plexus
Which artery does the superior rectal artery originate from?
inferior mesenteric
In which age group is risk of chronic hepatitis B infection is highest?
Neonates
In a healthy adult, in which region of the abdominal cavity does the spleen normally lie?
Left hypochondrium
At the level of which ribs does the spleen lie?
left ribs 9-11
List 4 structures that lie between the spleen and the lower left ribs
peritoneum
diaphragm
left lung
pleura/pleural cavity
Through which fold of peritoneum does the splenic artery pass to reach the spleen?
splenorenal ligament
In the spleen, are lymphocyte aggregates a feature of white pulp or red pulp?
white pulp
In the spleen, are splenic cords a feature of white pulp or red pulp?
red pulp
In the spleen, are splenic sinusoids a feature of white pulp or red pulp?
red pulp
In the spleen, are central arterioles a feature of white pulp or red pulp?
white pulp
In the spleen, are lymphoid nodules a feature of white pulp or red pulp?
white pulp
In the spleen, are penicillar arteries a feature of white pulp or red pulp?
red pulp
Give 4 functions of the adult human spleen
1) iron storage
2) phagocytosis of old/damaged RBC
3) phagocytosis of old/damaged WBC
4) immune response to circulating antigens
5) production of B and T cells
Which organ is most commonly damaged in abdominal trauma?
spleen.
blows over lower left chest area/upper abdomen can cause ribs to fracture and spleen to rupture
causes significant haemorrhage and potentially shock
immediately splenectomy is usually needed to prevent death from blood loss
What is the result of a splenectomy?
person can live without a spleen as red marrow and liver take over some of the spleen’s functions.
person will have reduced immunity to encapsulated bacteria, may require vaccination/prophylactic antibiotics
What is the most likely site for a bone marrow biopsy?
iliac crest
define anaemia
reduction in Hb concentration below the normal range for an age/sex-matched population
Name 2 micronutrients other than iron that are essential in RBC formation
folate
B12
What is the major site of EPO production?
peritubular interstitial cells of the kidney (85%), 15% is produced in the liver
What is the major stimulus for EPO production?
hypoxia
What microscopic features are typical of iron deficiency anaemia?
Microcytic (small RBC) and hypochromic (pale RBC)
IDA can cause glossitis. What feature of the tongue atrophies to give the smooth appearance?
filiform papillae
Which muscle of the tongue moves the tongue posterosuperiorly? (backwards and upwards)
styloglossus
Which CN provides most of the sensory innervation to the oropharynx?
glossopharyngeal
What are the phases of swallowing and is each voluntary/involuntary?
1) oral - voluntary
- food rolled into a bolus and tongue arches to push it backwards
2) pharyngeal - involuntary
- elevation of soft palat (closes nasopharynx)
- pressure of food on pharyngeal wall stimulates receptors which activates relexes (i) inhibition of respiration (ii) raises the larynx (iii) closes the glottis
- passage of food bolus downwards tilts epiglottis backwards
- waves of contractions sweeps through the pharyngeal muscles and food is propelled towards the UOS
3) oesophageal - involuntary
- reflex relaxation of UOS
- sphincter closes when food has pass3es
- glottis opens and breathing resumes
- peristaltic waves propel bolus forward
- LOS relaxes and food enters stomach
Name the principal muscles that move the food bolus through the pharynx
constrictor muscles
What is the main factor preventing food from entering the larynx?
sphincter mechanism
List 4 lymphoid tissues or organs
1) thymus
2) spleen
3) tonsils
4) MALT/Peyer’s patches
5) lymph nodes
What is the composition of reticular fibres in lymphoid organs?
forms internal skeleton
type IV collagen fibres - have affinity for silver stain
What are 2 principal functions of a lymph node
1) filtration of lymph
2) immune response to lymph-borne antigen
Why are T cells called T cells?
T stands for ‘thymus dependent’
Which type of lymphocyte is predominantly located in the outer cortex of a lymph node?
B cells
Which type of lymphocyte is predominantly located in the deep cortex of a lymph node?
T cells
Which type of lymphocyte is predominantly located in the medullary cords of a lymph node?
B cells
3 functions of the red pulp of the spleen
1) removes old and damaged red blood cells
2) stores up to one third of the body’s supply of platelets
3) red pulp can also act like bone marrow, producing new red blood cells. Usually this stops after birth but may start again in some people with certain diseases
Murphy’s sign
elicited in patients with acute cholecystitis by asking the patient to take in and hold a deep breath while palpating the right subcostal area. If pain occurs when the inflamed gallbladder comes into contact with the examiner’s hand, Murphy’s sign is positive
McBurney point
point over the right side of the abdomen that is one-third of the distance from ASIS to the umbilicus.
Roughly corresponds to the most common location of the base of the appendix where it is attached to the cecum.
Deep tenderness at McBurney’s point, known as McBurney’s sign, is a sign of acute appendicitis
