Flashcards in Liver Deck (111):
In which anatomical region is the liver found?
R hypochondric and epigastric area
Which ligament splits the R/L lobe of the liver and connects to the peritoneum?
Which ligament is a remnant of the umbilical vein, where is it found?
On free border of falciform lig
Which ligaments attach the superior border of the liver to the diaphragm?
Coronary L/R (central to liver midline)
Triangular L/R (lateral to liver midline)
What are the 4 lobes of the liver?
Right + Left
Quadrate (between ligamentum teres and gall bladder fossa)- Most inferior
Caudate (between sagittal fissue and groove for IVC)
What are the two surfaces of the liver?
Diaphragmatic (ant/ sup/ post)
Where are the subphrenic recesses found?
Between liver and diaphragm (either side of falciform lig)
Where are the subhepatic recesses found?
Between liver and transverse colon
Which ligaments form the lesser omentum?
Hepatoduodenal and hepatogastric
What is morrisons pounch?
R subhepatic space between liver and R/kidney
- Deepest part of peritoneum when lying supine so where fluid is most likely to collect
What is found in the right sagittal fissue?
Groove for IVC and gallbladder
What is found in the left sagittal fissure?
Groove for ligamentum teres and ligamentum venosum (remnant of ductus venosus in fetus)
The horizontal groove contains the porta hepatis, what is the PH and what passes through it?
Its a ~ 5cm fissue, several structures pass through:
Hepatic portal vein/ hepatic artery proper (in)
Common bile duct (out)
Sympathetic nerves (to T7)
Hepatic branch (CN X)
What surrounds the liver?
Consists of t2 collagen and has lots of pain fibres
Where does pain from the liver refer to?
Upper R quadrant
Where does the liver receive blood from?
Hepatic artery proper (branch of common hepatic)- 25%
Hepatic portal vein - 75%
How does the hepatic artery proper arise?
AA > coeliac trunk > common hepatic > hepatic proper
What is the venous drainage to the liver?
3 hepatic veins to IVC
What supplies SNS and PNS to the liver?
SNS: From T7 (hepatic/ coeliac plexus)
PNS: Vagus and R phrenic nerve
What does SNS stimulation of the liver do?
(More glucose breakdown)
What do both the hepatic artery proper and hepatic portal vein do just before reaching the porta hepatis?
Bifurcate (just inf to porta hepatis)
Where does the hepatic portal vein originate from and what veins contribute to it?
Just post to neck of pancreas
Sup mesenteric vein (from SI) joins splenic vein (which has been joined by inf mesenteric vein from LI)
What function begins at wk 4 in the embryo which initially takes place mainly in the liver?
Liver is main site for 2nd to 7th month
Bone marrow kicks in ~5months
Where does the liver come from embryologically?
Liver bud on foregut around ~wk 3
What is the histological composition of the liver?
Around 100,000 lobules per lobe
Each lobule is a hexagon with a central vein @centre and a portal triad (hep art/ HPV/ bile duct) at each of the 6 corners
In a histological context, what are liver 'plates'?
1 cell thick lines of hepatocytes
Sinusoids (small veins) run between each plate to drain them into the central vein
What property of liver plates allows passage of large solutes from blood to interstital fluid?
No basement membrane
How to hepatocytes increase their surface area?
They are covered with microvilli
What is the function of stellate cells in liver?
Storage for retinoids (vit A) and source of growth factors for hepatocytes. They secrete collagen
Which phagocytic cells remove particulate material from portal blood in liver?
What is the function of Kupffer (stellate reticuloendothelial) cells?
Macrophage like cells which engulf pathogens and debris
They also store iron/tin/mercury
What is the function of LCAT (lecithin-cholesterol acyltransferase)?
What type of hepatitis is uncommon in England, with cases largely confined to intravenous drug users? Most people being infected with this type are able to fight off the virus and fully recover within a couple of months?
Which enzyme converts glucose to glucose-6-phosphate?
Hexokinase aka glucokinase
At which stage does the substrate become committed to Kreb’s cycle?
Conversion of pyruvate to acetyl coA
What is the path taken by blood which is in the sinusoids?
Sinusoid > central vein > hepatic veins > IVC
Which cells in the liver store iron/ tin and mercury?
What are bile caniculi?
Collect bile from hepatocytes
What path does bile take after leaving a hepatocyte?
Bile caniculi > bile ducts (in triad) > R/L hepatic ducts > common hepatic duct > EITHER:
Cystic duct > gall bladder
or common bile duct > duodenum
In addition to the classical lobule structure, what two other structural classification systems could be used in the liver?
Portal lobule- Triangles with central vein at each corner and portal triad in the centre (emphasises endocrine)
Acinus- elliptical unit with portal triad at centre and central vein at each pole (emphasises endocrine)
In the acinus classification there are 3 zones which represent metabolic activity, what are these zones?
1- PERIPORTAL (most oxygenated blood so most metabolic activity and most susceptible to damage)
3- CENTRILOBULAR Most susceptible to ischemia
What lines sinusoids?
Discontinous, fenestrated epithelium
Persinusoidal (aka stellate) cells
Stellate cells are also known by what name?
What cells contribute most to fibrosis when the liver is damaged?
Stellate (perisinusodal/ Ito) cells
Name three characteristics of hepatocytes?
Retain eosin stain
Large with round nuceli
Over 50% are tetraploid (4x chromosomes)
How do hepatocytes connect with perisinusoidal spaces and bile caniculi?
On both sides!
Where are perisinusoidal cells found?
Between hepatocytes and sinusoidal endothelial cells in the perisinusoidal space (of disse)
The liver receives approximately what % of the resting cardiac output?
What is the livers role in protein synthesis?
Snythesises all plasma proteins except gamma globulins (it receives AA's from intestines/ muscles)
What is transamination?
Transfer of -NH2 group (usually from AA to keto acid)
What equation is catalysed by the enzyme "Alanine transaminase (ALT)"?
Glutamic acid + Pyruvic acid
Ketoglutamic acid + Alanine (An amino acid)
What is albumin and what is its function?
Makes up 50% of blood protein
Transports hydrophobic substances
Maintains osmotic pressure
Name 4 hydrophobic substances which are carried by albumin?
Drugs/ fatty acids/ bilirubin/ hormones
Which protein synthesised by the liver can indicate liver cancer or metastasis?
(Synth by yolk sac or rapidly dividing hepatocytes)
How are amino acids from tissue excreted?
First converted to keto acids (ketoglutarate etc)
Then eventually converted to urea and excreted
What do hepatocytes do following a meal?
Take up blood glucose and covert it to glycogen
(which is then either kept as glycogen or converted to lipid)
If blood glucose drops what two processes begin in hepatocytes?
Glycogenolysis (glycogen to glucose)
Gluconeogenosis (synth new glucose)
Gluconeogenesis creates new glucose from what substances?
Glycerol (from fat)
Alanine and glutamine (from proteins)
Which enzyme facilitates glycogenolysis?
Removes 1 glycogen branch at a time by replacing it with phosphate
What is the Cori (Aka lactic acid cycle)?
Lactate > (re-oxidised) to Pyruvate > glucose
Which substances regulated the livers control of blood glucose?
Insulin (tries to lower blood glucose)
Glucagon (tries to increase blood glucose)
Which enzyme exists in the liver (and kidney cortex/ B cells of pancreas) and allows glucose to be released from cells?
Most fat in the body is in what form?
How do lipids travel to the liver?
Most bypass hepatic portal circulation and travel via lymph
(remember insoluble so need to be bound to proteins- lipoproteins)
What lipoproteins are synthesised by the liver (write them in decending size order)?
VLDL > IDL > LDL > HDL
What are chylomicrons?
The smallest lipoproteins (made mainly of triglycerides), they are secreted by enterocytes of the intestine then travel via lymph to the systemic circulation then to the liver
What happens to chylomicrons when they reached the liver?
Lipoprotein lipase enzymes hydrolyses them
(Into FA's and glycerol)
FA's are then stored or transported in plasma via albumin
Where is cholesterol produced? What regulates cholesterol production?
Regulated by current cholesterol levels
What is the mevalonate cycle?
Acetoacetyl-CoA + Acetyl Co-A =
Cholesterol (via ~20steps)
Which vitamins can be stored in the liver?
Fat soluble (ADEK)
- Liver disease can lead to deficiency
Where is vitB12 absorbed and how is it stored?
Absorbed in terminal ileum with IF
2-3years worth can be stored in the liver
How is the liver involved with folate cycles?
Stores folate (enough for 2-3 months) and converts it to active form (tetrahydrofolate) when needed
Which deficiency is more common, folate or vitB12?
Folate (as liver can store months worth, not years)
Commonly seen in alcoholics/ cancer patients/ poor diet
Name 7 things stored in the liver?
Fat/ glycogen/ vit ADEK/ iron/ folate/ B12/ copper
What is deamination?
The stripping of amino (-NH2) groups from AA's
Done in protein breakdown (produces ammonia NH3)
How is ammonia converted to urea and what cells do this?
Urea (ornithine) cycle
Done by hepatocytes in periportal zone (zone 1)
What complication relating to NH3 results from liver failure?
Less conversion of ammonia to urea means a build up and ammonia toxicity
This can impair cerebral blood flow/ O2 use
What is bile and what is it's function?
Aqeous, alkaline, green/yellow liquid
Elimination of waste
Emulsifies fats to facilitate digestion and absorption
What are the components of bile?
Bile salts (aka bile acids)
Pigments (bilirubin/ biliverdin)
Water and electrolytes
What are the two main bile acids (bile salts)
What are micells?
Spheres formed by bile acids in water
(As they have hydrophillic and hydrophobic ends)
Where are bile salts produced and what are they produced from?
Hepatocytes (from cholesterol)
What is enterohepatic recycling?
95% bile salts are reabsorbed in the terminal ileum
(~6x per day)
How much bile acid to you produce each day?
500mg (to replace 5% lost in faeces)
How is bile acid synthesis controlled?
Absorption of BA's negatively feeds back to hepatocytes
How do bile acids help stimulate flow of bile?
Their osmolarity draws in water
What are the causes of liver cirrhosis?
Non-alcoholic fatty liver disease
What are some of the common presenting S+S for liver cirrhosis?
~40% asymptomatic until complications
Oedema/ ascities (due to low albumin)
Easy bruising (due to low vit K)
Osesophageal varies- vomit blood (due to portal HyperT)
Jaundice/ plamar erythema
Why can patients with liver failure experience gynacomastia?
Impaired hormone break down
Why can patients with liver failure experience leukonychia?
Low levels of albumin
What tests could be done to diagnose liver cirrhosis?
AST/ALT/ALP/ Bilirubin (all raised)
Gamma-GT is raised in alcoholics
Why can patients with liver failure experience pruitus?
Excess bile salts causes itch
How much of the liver must be affected before cirrhosis is noticed?
Name three complication of portal hypertension?
Varicies (caput medusa/ spider naevi)
Why can patients with liver failure experience vomiting of blood?
Due to oesophageal varicies caused by portal hypertension
Name two treatments for itching in liver disease?
Antihistamines (Cetirizine, fexofenadine, or loratadine)
Colestyramine (binds to bile salts to stop re absorption)
How does unconjugated bilirubin travel in the blood?
Bound to albumin
What happens to unconjugated bilirubin when it reaches the liver?
It becomes conjugate with glucuronic acid
ka - bilirubin diglucuronide
(Catalysed by 'glucuronyl transferase' in smooth ER)
What happens to conjugated bilirubin in hepatocytes?
Actively transported in bile canaliculi > colon (small amount is lost into blood and excreted via urine)
What happens to bilirubin once it reaches the colon
Bacteria deconjugate and metabolize the bilirubin into colorless urobilinogen, which can be oxidized to form urobilin and stercobilin (gives faeces brown colour)
What is the clinical definition of jaundice?
Plasma bilirubin > 50umol/L
What are the most common causes of jaundice?
Haemolytic disease/ RBC destruction/ Sickle cell
Obstruction of bile ducts of hepatocyte damage
What is pre-hepatic jaundice?
HAEMOLYTIC (Unconjugated bilirubin)
Livers capacity to conjugate is overcome
Raised levels of unconjugated bilirubin
How can the urine reveal clues about whether jaundice is pre-hepatic or post-hepatic?
Pre-Hepatic: Unconjugated bilirubin is not soluble so doesn't go into urine
Post-hepatic: Conjugated bilirubin is soluble so turns urine dark (also turns stools pale)
Name two causes of post-hepatic jaundice?
Pancreatitis/ gall stones
What is post-hepatic jaundice?
OBSTRUCTIVE (Conjugated bilirubin)
Increase in conjugated bilirubin as bilary tree blocked and cholestasis occurs
Name two ways to differentiate between pre and post hepatic jaundice?
Itching (only in post-hepatic due to cholestasis)
Dark urine (only in post-hepatic- due to conjugated bilirubin)
Pale stools (only in post-hepatic- due to conjugated bilirubin)
What is hepatocellular jaundice?
Due to damage of hepatocytes
A mix between conjugated and un-conjugated bilirubin
What is Gilberts syndrome?
Reduced amounts of enzyme 'UDP-gluconrnyl transferase' leads to increased bilirubin and fatigue
Affects 2-7% of population
Jaundice with itching, dark urine and pale stools indicates what type of jaundice?