The Digestive System - Pancreas and Liver Flashcards
Imaging modalities of hepatobilliary system
Ultrasound (trans-abdominal and endoscopic)
CT
MRI
Nuclear med e.g. PET staging
Angio e.g. tumour embolisation
Radiographs - not v useful
Functions of liver
Helps manage body’s metabolism
Bile production
Detoxification
What is the liver covered by
Serous membrane (visceral peritoneum) that suspends liver form Abdominal wall and diaphragm
5 peritoneal folds (ligaments)
Ligaments of liver
Coronary
L triangular
R triangular
Falciform
Round
Lobes of liver
R & L - seen from superior view
Also posterior caudate lobe and anterior quadrate lobe - seen from inferior view
What is the posterior caudate and a anterior quadrate lobes of the liver separated by
Porta hepatitis - hepatic artery, hepaxtcic portal vein, common hepatic duct
Role of hepatic artery
Carries oxygen-rich blood from heart
Role of hepatic portal vein
Carries nutrient-rich blood from GI system incl pancreas
Role of common hepatic duct
Drains bile from liver into gallbladder
Functional unit of liver
Hepatic lobules
Portal triad of liver
Hepatic artery
Portal vein
Common bile duct
Blood vessels drain into sinusoids, before scarring blood to central vein
What do hepatocytes act as a store for
Vitamine A, D, E, K, B12
Minerals incl Fe and Cu
Synthesis as a function of heptovytes
Proteins incl albumin and coag factors
Lipoporteins inlc VLDL and HDL
Stellate reticuloendothelial cells
AKA Kupffer cells
Destroys old RBCs, WBCs, bacteria and foreign substances
Why do we need bile
Digestion
Absorption of fat and fat-soluble vitamins in small intestine
Has a role in immunological defence
Bile composition
Bile salts (from cholesterol)
Water
IgA
Bilirubin
Where is bile canaliculi found
Between adjacent hepatocytes
Drains into bile ductules –> bile ducts
Ducts in gallbladder
R and L hepatic duct combine to for common hepatic duct
Common hepatic duct combines with cystic duct to bring bile to gallbladder
How does drug metabolism in the liver typically work
Process turns lipophilic molecules into hydrophilic molecules which can be excreted/ eliminated
3 phases of drug metabolism
Phase 1 - modification (mainly CYP450)
Phase 2 - conjugation
Phase 3 - further modification and excretion
Common reactions in phase 1 of drug metabolism
Oxidation
Sulphodixation
Dealkylation
Deamination
Factors affecting drug metabolising enzymes
Pregnancy
Age
Gender
Polymorphisms
Organ transplant
Liver disease
Kidney disease
Drug-drug interaction
Infl mediators
DM
Why are LFTs an over-simplification
Poor markers of synthetic function (ability to make things)
Severe liver disease can occur w/out abnormal LFTs
What do LFTs consist of
Bilirubin
Albumin
Globulin
ALT
ALP
Gamma GT
NOTE - platelet count, prothrombin time (INR)
What may cause a high bilirubin
Over production of bilirubin or failure of excretion
Causes of increased bilirubin production –> hyperbilirubinaemia
Haemolysis
Ineffective erythropoiesis
Blood transfusion
Resorption of haemotomas
Causes of decreased hepatic uptake —> hyperbilirubinaemia
Gilberts’s syndrome (also decreased conjugation)
Drugs e.g. rifampicin
Where are aminotransferases found
Liver, muscle, heart, kidney, brain and pancreas
Intracellular enzymes released injured hepatocytes
What are aminotransferases a measure of
Necro-infl
Types of aminotransferases
Alanine aminotransferase (ALT) and aspartate aminotrasnbferase (AST)
ALT is more liver spp
ALT: AST ratio can be useful
Causes of raised aminotransferases - pathology
Alcohol
NAFLD
C/c hep B and C
CCF
Causes of raised aminotranferases - disorders
AI diseases
Haemachromatosis
Wilsons - excess Cu
A1AT deficiency
Coeliac
Meds causing raised transaminases
NSAIDs
Abx
HMG-CoA reductase inhibitors
Antiepileptic drugs
Anti-TB drugs
Illicit drugs use
ALP as an LFT
Sensitive test for biliary obstruction but not spp
Physiological causes for raised ALP
Women in 3rd trimester of pregnancy
Adolescents
Benign, familial
Pathological causes for raised ALP
Bile duct obstruction
PBC
PSC
Drug-induced cholestasis
Metastatic liver disease
Bone disease
Where is gGT present
In many organs, found particularly high in epithelial cells lining bile ducts
gGT as a maker of biliary obstruction
Typically associated w/ ALP
What is gGT inducible by
Alcohol
Phenytoin, carbamazepine, barbiturates
Sex hormones
Causes of raised gGT
Pancreatic disease
Alcopholism
COPD
Renal failure
DM
MI
Hepatitic vs cholestatic picture of LFTs
Hepatitic - Increased ALT and AST (ALT > ALP), increased alb, c/c low albumin
Cholestatic - increased gGT and ALP (ALP > ALT)
Haematological tests as LFTs
Prothrombin time is best marker of synthetic function - increased INR
Platelets best marker of portal HTN
Low albumin (typically seen w/ raised CRP)
AST: ALT ratio
ALT: AST 2:1 in alcohol related liver disease
ALT: AST in NAFLD and c/c viral hep approaches 1:1 as fibrosis progresses
Gilbert’s syndrome
Inability to correctly conjugate bilirubin
Anatomy of pancreas
Soft, lobulated retroperitoneal organ
Crosses the trabnspyloric plane
Consists of head, neck, body and tail
Where is uncinate process of pancreas found
Behind superior mesenteric vessels
Where is the neck of pancreas found
In front of portal veins
Where is the tail of the pancreas found
Touches hilum of spleen
Why is the pancreas’ rship to the lesser sac important
In pancreatitis, lesser sac can fill with fluid
2 components of pancreas as a gland
Exocrine
Endocrine
Which anatomical structures are anterior to the pancreas
Stomach
Lesser sac
SMA
Which anatomical structures are posterior to the pancreas
Aorta
IVC
R renal artery
R & L renal veins
Superior mesenteric vessels
Splenic veins
Hepatic portal vein
L kidney
L suprarenal gland
Which anatomical structures are superior to the pancreas
Splenic artery
Which anatomical structures are lateral to the pancreas
Spleen
Which anatomical structures are medial to the pancreas
Duodenum (descending and horizontal parts)
Where is the head of pancreas found
Lies in loop of D1/D2 as it exits stomach
Types of tissue in pancreas
Endocrine (tubular) - 90%
Endocrine (islets) - 2%
Interstitial
Where is exocrine tissue found in the pancreas
Surrounding interlobular ducts
Examples of endocrine cells in pancreas
Islets store their hormones in distant locations
Beta - insulin
Alpha - glucagon
Delta - SST
PP (pancreatic peptide) - beta cells
PP in disease response
Beta cells get replaced with these in 2’ DM
Interstitial tissue of pancreas
Specialised pancreatic stellate cells involved in fibrogenesis of pancreatitis and cancer
Ca deposition in c/c pancreatitis
Functional unit of pancreas
Lobules
Structure of ducts in pancreas
Interlobular ducts come off main duct of pancreas
Interlobular ducts go INTO lobules
Intercalated ducts go into acinus (secretory epithelium)
Effect of autonomic nervous system on pancreas
Heavily innervated by ANS
Regulates glandular production
Regulate blood flow
What do pancreatic acinus cells make
Enzymes and zymogens
These are then secreted into lumen of duct
What are proteases produced as zymogens
Proteases are v powerful
Only activated at small bowel
Examples of zymogens
Trypsinogen
Chymotrypsiongen
Proelastase
Examples of active enzyme produced by pancreas
Alpha amylase
Lipase
RNAase
DNAase
Control of exocrine secretion of pancreas
Response to meal - cephalic, gastric and intestinal phase
Other important driver incl acid in small intestine, fat, proteins and bile acids
Protease levels in gut stimulate/inhibit secretion via -ve feedback
Pancreatic secretions
Mixture of fluid, bicarb and digestive enzymes in response to variety of n neurotransmitters and hormones
Activation of zymogens
Important in pathophysiology of a/c pancreatitis
Trypsinogen comes out of pancreas and is activated by enterokinase to form trypsin, which then activates all the other zymogens
Common pancreatic procedures
Pancreatomies but pancreatic soaring surgery
Whipple’s procedure
Frey’s procedure
Whipple’s procedure
Pancreaticoduodenectomy
Complex procedure to remove head of pancreas, duodenum, gallbladder and bile duct
Issues w/ Whipple’s procedure
Issues w/ sterility of small bowel - can cause bacteria overgrowth and small bowel should be sterile
When is Frey’s procedure done
For benign lesions
Where are pancreatic ductal cells found
Just after acinus - cemntroacinar cells (carbonic hydrase)
Proximal vs distal intercalated pancreatic ductal cells
Proximal - low cuboidal
Distal - more cuboidal/ columnar and contain more vesicles and granules
Main job of pancreatic ductal cells
Make a bicarb rich fluid
What happens as more HCO3- is secreted in pancreatic secretion
More Cl- is reabsorbed
Link between CF and c/c pancreatitis
How are biliary canaliculi held together
By gap junction between two heoaocytes
Adherens junctions
Tight junctions
How does water enter biliary canaliculi
Water can enter via aquaporin 8 (regulated by cAMP) and aquaporin 9
Also paracellular & transcellular
Pathways to make bile slats
Classical
Alternative
Neural (extra-hepatic)
What are bile salts produced from
Cholesterol
What are the primary bile slats
Cholic acid
Chenodeoxycholic acid
Secondary bile acids
Primary bile salts that have been conjugated and then chemically modified in the intestine
Examples of 2’ bile acids
Deoxycholic acid
Lithocholic acid
UDCA
What is hepatitis
A/c or c/c parenchymal liver damage
Dominant sx of hepatitis
Jaundice (icterus)
Detectable clinically when the serum bilirubin >50 mmol/L
What is hepatitis associated with in the liver
Rise fo ALT in plasma
Los of excretory and synthetic functions
Describe the variability of the extent if damage in hepatitis
V variable
From spotty or focal necrosis to massive hepatic necrosis
There is also infiltration of portal tracts and lobules by lymphocytes
Histological features of hepatitis
Hepatocytes shows degenerative changes
Hepatocytes undergo necrosis
Necrosis is maximal in zone 3
Degernative changes seee in hepatocytes in hepatitis
Swelling
Cytoplasmic granulation
Vacuolation
Necrotic changes seen in hepatocyte sinhepatitis
Become shrunken
Eosinophilic Councilman bodies
Causes of hepatitis
Viral infections
Drug induced (e.g. paracetomol)
Alcohol
NAFLD
AI hepatitis
Systemic viral infections causing hepatitis
EBV and CMV, HSV, VSV
Yellow fever
VHF
Rubella
Mumps
Coxsackie B
Px of hepatitis
Abdo pain
Pruritus
Muscle and joint aches
N & V
Jaundice
Fever (viral cause)
Features of Hep C
HCV is usually symptomless for decoded while damaging liver
Accounts for 70% cases of c/c liver disease
RNA virus spread by blood and bodily fluids
Signs of hepatitis
RUQ pain
Hepatomegaly
Jaundice
Pyrexia
Transmission of HCV
Parenteral
Permucosal - sexually
Vertical
Which condns are HCV associated w/
Liver disease
DM
B-cell proliferative disorders
Depression
Cognitive
Risk factors associated w// HCV
Tranfusion/ transplant w/ unsterilised equipment
IVDU
Haemodialysis (duration of treatment)
Multiple sex partners
Natural hx of HCV
Most pts (80%) fail go clear virus and develop c/c hepatitis (>6/12) —> cirrhosis, HCC
Features of c/c HCV infection
C/c persistent hepatitis
Cirrhosis
HCC
Extrahepatic disease - mixed essential cryoglobulinaemia, Glomerulonephritis, sporadic porphyria cutanea tarda
Mx of HCV
Directly acting antiviral - used in combination (given for 8/52 to 12/52)
Protease inhibitors - telaprevir, simeprevir
NS5 A/B inhibitors - Elbasavir, Velpatasivir
hCBV is totally curable
Hep D virus
Defective RNA virus requiring hep B for replicate
Types of infection of HDV
Coinfection - HBV and HDV at same time
Superinfection - development of HDV in pt w/ pre-existing HBV
Decompensated cirrhosis
Inability of liver to carry out normal functions
Features of decompensated cirrhosis
Development of ascites
Encephalopathy
Jaundice
Coagulopathy
GI bleeding
HDV clinical progression
Most severe form of viral hep
C/c infection –> cirrhosis –> HCC
Mx of HDV
Only treatment for c/c HDV
Pegylated IFNa
Testing for HCV
Hep C antibody screen
Hep C RNA confirms dx, csalulate viral load, assess genotype
Features of HEV
RNA virus transmitted by faecal oral route
Normally produces only mild illness, except in immunocompromised and pregnant
No vaccination
Characteristics of a/c liver failure
Confusion (i.e. encephalopathy)
Jaundice
Asterixis
GI bleeding
Ascites
Bruising (high INR)
What is cirrhosis
Severe, irreversible fibrosis of liver
Which complications are cirrhosis associated w/
HCC
GI bleeding
Spontaneous bacterial peritonitis
What is c/c liver disease characterised by
Caput medusae
Splenomegaly
Palmar erythema
Dupuytren’s
Leuconychia
Gynaecomastia
Spider naevi
Features of HBV
2nd most important carcinogen
DNA virus
Causes 1 million deaths/ yrs
100x more contagious than HIV
modes of transmission of HBV
Sexual
Parenteral - HCWs at increased risk
Perinatal
Transfusion
Nature of HBV infection
Most people recover within 2/12
Only 10% are symptomatic
10% become c/c HBV carriers
Viral markers of HBV
HBsAg
HBeAg
HbcAg
HbsAb
HBV DNA
HBsAg for HBV
Surface antigen
Used as general marker of active infection
HBeAg for HBV
E antigen
Marker of viral load and implies high infectivity
HBcAg for HBV
Core antibodies
Implies past or current infection
HBsAb for HBV
Surface antibody
Implies vaccination or past or current infection
HBV DNA for HBV
Direct count of viral load
Vaccination for HBV
Involves injecting Hep B surface antigen - 3 doses
Vaccinated pts are tested to confirm response to vaccine
Prevention of HBV infection
UK antenatal screening
Exposure-prone procedure for HBV infected HCW
Global eradication programme (immunisation)
Prophylaxis
Prophylaxis for HBV
Pre exposure is active immunisation
Post-exposure is accelerated active immunisation
Approach to c/c HBV infection therapy
Treat when they enter the immune elimination phase and develop active hepatitis
(ALT elevation and bx evidence of c/c hepatitis and fibrosis)
Treatment for c/c HBV infection
Immunomodulators - pegylated IFNa
Nucleoside analogues - lamivudine
Nucleotide analogues - adefovir, tenofovir
Given for 48/52
Features of HAV
Most common viral hep
RNA virus transmitted by faecal-oral route
Rarely, fulminant hep ensues but never c/c liver disease
HAV transmission
Close personal contact (e.g. household contact, sexual contact)
Homeless person - poor hygiene
Drug use
Contaminated food
Blood exposure
Px of HAV
Nausea
Vomiting
Anorexia
Jaundice
Can cause cholestasis