FRS 4. ANATOMY OF THE LIVER AND BILIARY SYSTEM

Question 1

What is the bare area of the liver?

Answer 1

section which is not covered by peritoneum
o Lies directly against the tissue of the diaphragm
o This region is bare because the connective tissue elements of the liver and diaphragm form from
a common sheet of tissue in the embryo  the liver grows outward from this

Question 2

Describe the venous drainage of the liver

Answer 2

 The IVC lies in a groove on the back of the liver

 Blood from the liver drains into 3 hepatic veins, which then open into the IVC

Question 3

What is the Hepatoduodenal ligament?

Answer 3

the bile duct, hepatic portal vein and hepatic artery lie in the free edge of the lesser omentum
Portion of the lesser omentum extending
between the porta hepatis and the superior part
of the duodenum. Contains the portal triad

Question 4

What is the pringle manoeuvre?

Answer 4

clamping of the hepatic pedicle

o Enables surgeons halt haemorrhage and find the source of bleeding by determining if it
originates from branches of the hepatic artery or the portal vein.
 allows time for repair
o When a clamp is applied to the pedicle, haemorrhage ceases if it is from either of these sources.
o If haemorrhage continues, the other likely sources of bleeding include the retrohepatic vena cava
and hepatic veins

Question 5

What are the four anatomical lobes of the liver?

Answer 5

o Left lobeand right lobes(that are separated along the attachment of thefalciform ligament
o Caudate and aquadrate lobes(which are part of the anatomical right lobe).

Question 6

What are the functional lobes of the liver?

Answer 6

distribution of the portal blood supply and biliary drainage of the liver allows the organ to
be functionally divided into four sectors, which are subsequently divided to give a total of eight
segments.
o Drained and supplied by different blood vessels and can therefore undergo surgical resection

Question 7

Where is the gallbladder located?

Answer 7

theright hypochondriac region
Lies in a fossa (groove) between the right and quadrate lobes on the inferior aspect of theliver
o Shares a minimal amount of connective tissue with the liver

Question 8

What are the divisions of the gallbladder?

Answer 8

• fundus
• body
• neck

Question 9

Describe the fundus of the gallbladder

Answer 9

rounded, end portion of the gallbladder; projects from the inferior border
of the liver.
o Fundus is located where the lateral rectus abdominis muscle reaches the
costal margin*
o The rectus abdominis muscle helps to flex the trunk (e.g. upon sitting up)

Question 10

Describe the body of the gallbladder

Answer 10

largest part; Occasionally in contact with transverse colon and proximal duodenum.

Question 11

Describe the neck of the gallbladder

Answer 11

gallbladder tapers to become continuous with the cystic duct, leading to the
biliary tree.
o Contains a mucosal fold calledHartmann’s Pouch.
o Thisis a common location for gallstones to become lodged, causing cholestasis.

Question 12

What does tenderness of the right hypochondriac region indicate?

Answer 12

results from inflammation of the gallbladder, e.g. with gallstones or malignancy of the biliary tract.

Question 13

Describe the lining of the gall bladder

Answer 13

o simple columnar epithelium - has an absorptive function (absorbs water to concentrate bile)
o some goblet cells

Question 14

How does the gallbladder secrete bile into the GIT?

Answer 14

via a series of ducts, known as the biliary tree.

ducts extend from the liver, communicating with the gallbladder and pancreas, and end at an
opening into the duodenum.

Question 15

Describe the biliary tree

Answer 15

Left + right hepatic ducts => common hepatic duct => common hepatic + cystic duct => common bile duct + pancreatic duct => hepatopancreatic ampulla of Vater

Question 16

What is the arterial supply of the gallbladder?

Answer 16

Supplied by the cystic artery.
o Derived from the hepatic artery
proper, a branch of the common
hepatic artery, which arises from the
coeliac trunk.

Question 17

What is the venous drainage of the gallbladder

Answer 17

Drained by the cystic vein
o Drains directly into the portal vein.
 The gallbladder also communicates with the liver through several very small veins and arteries.
 Lymph from the gallbladder drains into thecystic node, situated at the gallbladder neck.

Question 18

What is the innervation of the gallbladder

Answer 18

The gallbladder receives parasympathetic, sympathetic and sensory innervation.
 Sympathetic and sensory fibres: coeliac plexus
 Parasympathetic innervation: vagus nerve
o Parasympathetic stimulation produces contraction of the gallbladder, and the secretion of bile
into the cystic duct.

Question 19

What is the main stimulator of bile secretion?

Answer 19

cholecystokinin, which is secreted by the
duodenum
 Food enters the duodenum, stimulating the release of CCK
 CCK stimulates:
o Gall bladder contraction
o Relaxation of the sphincter of the hepatopancreatic ampulla

Question 20

Describe a classical liver lobule

Answer 20

 Prism with a central vein (drains into hepatic
vein)
 Prisms may differ in size
 Corners of lobules have portal triads
o Hepatic artery
o Hepatic portal vein
o Bile duct

Question 21

Describe a liver acinus

Answer 21

 Roughly ellipsoidal area of hepatocytes centred
around a bile ductule
 This area drains into said ductule
Zones 1-3 in liver acinus:
 Zone 1: periportal
o Hepatocytes actively synthesise glycogen and plasma proteins
o Oxygen concentration in sinusoidal blood is high
 Zone 2: intermediate
 Zone 3: perivenular (venous drainage)
o Low oxygen concentration
o Detoxification
o Hepatocytes susceptible to hypoxia

Question 22

What is glisson’s capsule?

Answer 22

thin layer of connective tissue that covers the liver

 A healthy liver contains a minimal amount of fibrous tissue

Question 23

Describe the histology of the bile ducts

Answer 23

o Lined by simple columnar epithelium, may be simple cuboidal in smaller ducts
o Very round nuclei
o Some smooth muscle and fibrous tissue in the wall

Question 24

Describe the histology of the hepatic artery

Answer 24

o Elongated nuclei (smooth muscle)
o Elastic layer
o Thick smooth muscle layer
o Endothelium appears convoluted

Question 25

Describe the histology of the hepatic portal vein

Answer 25

o Large, irregularly shaped lumen | o Not much smooth muscle in its wall

Question 26

What are the three types of alcoholic liver disease?

Answer 26

1) Fatty liver (steatosis) 2) Alcoholic hepatitis +/– hepatic fibrosis 3) Cirrhosis

Question 27

Describe hepatic liver metabolism

Answer 27

Two main metabolic pathways: 1. Cytoplasmic alcohol dehydrogenase (ADH) 2. Microsomal ethanol oxidising system (MEOS) o Both oxidise alcohol to produce acetaldehyde o Acetaldehyde is converted to acetate then acetyl-coA o Acetyl-coA enters tricarboxylic acid cycle in mitochondrion, leading to fatty acid formation

Question 28

What are raised GGT levels a sign of?

Answer 28

GGT is found in the SER of hepatocytes, the site of MEOS. Induction of MEOS therefore stimulates an increase in GGT, as reflected by liver function tests

Question 29

What is MEOS?

Answer 29

MEOS = Microsomal ethanol oxidising system uses cytochrome P450 enzyme induction by excess alcohol alters metabolic activity, and affects metabolism of drugs e.g. paracetamol o Affects drug dosage and toxin (metabolite) production

Question 30

What is steatosis?

Answer 30

 Fatty liver is the accumulation of triglycerides and other fats in the liver cells.  The amount of fatty acid in the liver depends on the balance between the processes of delivery and removal  Early and reversible consequence of excessive alcohol consumption.  In some patients, fatty liver may be accompanied by hepatic inflammation and liver cell death (steatohepatitis)

Question 31

How does alcohol increase hepatic lipid?

Answer 31

 Altered hepatocyte fat metabolism  Increased peripheral fat mobilisation  Reduced lipoprotein synthesis

Question 32

How does alcohol alter hepatocyte fat metabolism

Answer 32

Lipid synthesis promoted and catabolism impaired with accumulation of cholesterol esters & fatty acids

Question 33

How does alcohol increase peripheral fat mobilisation?

Answer 33

o Fatty acid formation from excess alcohol disrupts systemic lipid metabolism, causing dyslipidaemia o The body is confused into thinking that there is not enough fat and mobilises peripheral fat stores

Question 34

Describe alcohol steatosis on microscopy

Answer 34

```  Lipid droplets in hepatocytes o Initially small: microvesicular o Then coalesce and are larger: macrovesicular o Seen after only 2 days alcohol excess o Rapid reversal on abstinence ``` NB: the lipid droplets are in HEPATOCYTES, not in adipocytes o There is no change in cell type

Question 35

Describe the microscopy of alcoholic hepatitis

Answer 35

 Fatty liver  Hepatocyte abnormalities: o Ballooning (sub-lethal cell injury) >Injured cells are unable to control their cell membrane and osmotic potential within the cell, leading to ballooning o Mallory bodies in cytoplasm > Cell’s cytoskeleton crumbles and clumps together o Necrosis o Neutrophil polymorph infiltration (inflammation) => many nuclei visible  Fibrosis o Initially perivenular & pericellular > Initially occurs in zone 3 because this is the site of alcohol metabolism o Later fibrous septa & maybe cirrhosis

Question 36

What are the complications of alcoholic cirrhosis?

Answer 36

``` o Portal hypertension  Portal-systemic shunts and varices  Ascites  Splenomegaly o Liver failure o Hepatocellular carcinoma in 3-6% ```