PBL 2: The liver Flashcards
Where is the liver located in the body (9 regions of the abdomen)?
Right hypochondrium
What are the 2 functional divisions of the liver?
Left and right lobe
Which lobe is the caudate and quadrate lobe a part of?
Right lobe
Which structures divides the left and right lobe of the liver?
Falciform ligament
What is the name of the thin fibrous capsule that covers the liver?
Glisson’s capsule
The liver is covered in ____ peritoneum except the ___ region
- Visceral peritoneum
- Bare area
The ____, ____ and _____ surface makes up the diaphragmatic surface of the liver?
Anterior
Superior
Posterior
What are the names of the 5 ligaments of the liver?
- Falciform ligament
- Coronary ligaments
- Triangular ligaments
- Hepatoduodenal ligament
- Hepatogastric ligament
Describe the falciform ligament of the liver?
- Attaches to the anterior surface of the liver to the inferior surface of the diaphragm.
- Forms an anatomical division between the left and right lobe of the liver
- Free edge contains the ligamentum teres.
Ligamentum teres is the remnant of which embryological structure?
Umbilical vein
Which ligament is the remnant of the umbilical vein?
Ligamentum teres
Describe the coronary ligaments of the liver?
- Two: anterior and posterior folds
- Attaches to the inferior surface of the diaphragm.
- Demarcates the bare area of the liver
- Anterior and posterior folds unite to form the left and right triangular ligaments on the left and right lobe respectively.
Describe the triangular ligaments of the liver?
2 types: Left and right
Formed by the union of the anterior and posterior coronary ligaments
Describe the hepatoduodenal ligament of the liver?
Part of the lesser omentum
Extends from the duodenum to the porta hepatis of the liver
Contains the portal triad
What are the structures that make up the portal triad?
Hepatic artery
Portal vein
Common bile duct
Name these different ligaments of the liver?
What is the key characteristic of the bare area?
Has no peritoneal covering
In direct contact with the diaphragm
What surface is the caudate and quadrate lobes?
Inferior surface
Name these lobes of the liver?
Which lobe is located more superiorly? Caudate or quadrate
Caudate is located superiorly compared to quadrate
What structure lies between the quadrate and the caudate lobe of the liver?
Porta hepatis
Describe the porta hepatis?
- Lies between the caudate and quadrate lobes in the right lobe of the liver.
- Transmits all the vessels, nerves and ducts entering and leaving the liver except the hepatic veins.
- Central fissure - contains portal vein, hepatic artery, hepatic nervous plexus, hepatic ducts, lymphatic vessels
Which blood vessel can be used to divide the liver into 8 segments?
Hepatic veins: right, middle and left
What is the arterial supply to the liver?
Dual blood supply
hepatic artery and portal vein
Describe the blood supply to the liver by the hepatic artery?
- Supplies 25% of the total blood supply to the liver
- Derived from the celiac trunk
- Supplies the non-functional tissue of the liver with blood supply.
List the arterial branches from abdominal aorta to right/left hepatic artery?
- Abdominal aorta
- Celiac trunk
- Common hepatic artery
- Right + Left hepatic artery
What are the branches off the celiac trunk?
First is the left gastric artery
Then the splenic artery and common hepatic artery
Describe the blood supply to the liver by the portal vein?
- Supplies 75% of the total blood supply to the liver
- Supplies the liver with partially deoxygenated blood
- Carries nutrients absorbed from the gut.
- The dominant blood supply to the parenchyma (functional) tissue of the liver.
Which vessel(s) is/are the venous drainage for the liver?
Hepatic veins
Describe the hepatic veins?
- Hepatic veins drain the blood from the liver
- They are formed from the union of central veins
- Drains directly into the inferior vena cava (i.e. not a part of the portal triad)
- 3 types: left, middle and right hepatic veins
What is the sympathetic nerve innervation for the perenchyma of the liver?
Innervated by the hepatic plexus which arises from the coeliac plexus
What is the parasympathetic nerve innervation for the perenchyma of the liver?
Vagus nerve
What does parenchyma mean?
Functional unit
What is the nerve supply to the non-parenchyma of the liver?
e.g. Glisson’s capsule
Innervated by the lower intercostal nerves
What are the cells of the liver known as?
Hepatocytes
The hepatocytes are arranged in ____?
Lobules
Each lobule of the liver is drained by?
A cental vein
At the periphery of each of these lobules there is the _____?
Portal triad
What shape is each lobule of the liver?
Hexagonal-shape
Draw the shape of a lobule of the liver?
Describe a lobule of the liver?
- Also known as an acinus
- Functional hepatic unit
- Consists of parenchyma supplied by the smallest portal tracts.
- Smallest portal tracts contain portal vein radicles, hepatic arterioles and bile ductules.
- The hepatocytes nearest to the triads are well supplied with oxygenated blood and therefore are more resistant to damage and do the majority of metabolic function. While hepatocytes further from the portal triad are closer to the central vein are less resistant to damage.
Name these different parts of the lobule in the liver
Name these different parts of the lobule?
The space between the sinusoid and the hepatocytes is known as?
The space of Disse
What is the function of the sinusoid?
Moves blood from the portal triad to the central vein
In doing so, blood moves out of the sinusoid into the hepatocytes.
What seperates each sinusoid?
Plates of arranged hepatocytes
Describe the structure of the sinusoid?
- Lack a basement membrane
- Loosely surrounded by specialised fenestrated epithelium and Kupffer cells.
Kupffer cell is a type of?
Resident macropages that line the sinusoids
capable of phagocytising bacteria and other foreign matter
Describe the stellate cell in the lobule?
- Store retinoids in their resting state
- Contain desmin, an intermediate filament.
- When activated, they contract causing the regulation of blood flow through the sinusoid.
What does the bile contain?
Bicarbonate
Cholesterol
Phospholipids
Bile pigments
Bile salts
What is the function(s) of the liver related to digestion and absorption?
- Secretion of bile salt, bicarbonate and organic waste products and trace metals
- Secretion of bile
- Solubilise water-insoluble fats
- Neutralise HCl entering small intestine from stomach
- Elimination in faeces
The left and right bile duct join to form?
The common hepatic duct
What does the gallbladder to do the bile?
Stores the bile
Concentrates it by absorbing some ions and water
What happens to the bile between meals?
It gets stored in the gallbladder
What is the name of the duct that branches off the common hepatic duct to the gallbladder?
Cystic duct
What happens to the gallbladder during a meal?
- The smooth muscles in the gallbladder wall are stimulated to contract
- When the smooth muscle is contracted, the bile that has been stored is injected into the duodenum via the common bile duct
What is the name of the duct that the cystic duct and common hepatic duct combine to form?
Common bile duct
What comes first from the liver:
A) common hepatic duct
B) common bile duct
Common hepatic duct
This hepatic means liver
While bile means for the bile i.e. the bile from the liver and the gallbladder
What is the normal length of time for a erthryocyte lifespan?
120 days
Name these different parts of the lobule of the liver?
Describe the cellular plates of the lobules?
Radiate from the central vein like a spokes in a wheel
Each plate is usually 2 cells thick (seen image)
Between the cells lie bile canaliculi that empty into the bile ducts
In addition to hepatic cells, which other two cell types line venous sinusoids?
- Endothelial cells
- Kupffer cells
Describe the components of an erythrocyte?
4 haem
4 globin
Each haem is made up of: One iron and 1 prophyrin ring
Bilirubin is a type of bile ___?
A) pigment
B) salt
A) bile pigment
Which component of the erthryocyte is the bilirubin formed from?
Prophyrin ring (derived from the haem group)
Name the four enzymes in the following picture of bilirubin metabolism?
In what form does the bilirubin move from the reticuloendothelial system to the liver?
Unconjugated bilirubin bound to albumin
Why does the unconjugated bilirubin need to be bound to albumin in blood?
Because U-bilirubin is hydrophobic
In which form does the bilirubin move from the liver to the small intestine?
Conjugated bilirubin
Which enzyme converts unconjugated bilirubin to conjugated in the liver?
UDP glucuronyl transferase
Which enzyme converts conjugated bilirubin to unconjugated bilirubin in the small intestine?
beta glucornoidase
The ____ bilirubin is stored in the gallbladder?
Conjugated
Name the 3 urobilinogens?
Mesobilinogen
Stercobilinogen
Urobilinogen
Which of the urobilinogens are reabsorbed to the liver?
Urobilinogen
____ gives faeces its brown colour?
Mesobilin
___ gives urine its yellow colour?
Urobilin
Draw the flowchart of the bilirubin metabolism?
Explain the pathophysiology of portal hypertension?
Increase pressure in the portal vein due to the blood due to a blockage in the circulation (either prehepatic, hepatic or posthepatic).
Leads to a back pressure of blood.
Blood flows into smaller blood vessels to divert to the systemic circulation, bypassing the liver.
These smaller blood vessels are not designed to carry these high volumes of blood.
Thus varices form, result is very fragile and sensitive areas to bleeding
Define portal hypertension?
- Portal hypertension is an increase in the pressure within the portal vein, at least 5mmHg greater than the IVC pressure.
- Many causes including etiologist pre-hepatic, hepatic and post-hepatic.
- The portal vein is important in carrying blood from the digestive organs to the liver.
What are the 3 major causes of portal hypertension?
Pre-hepatic cause include IVC thrombosis.
Hepatic cause include cirrhosis
Post-hepatic cause
What are the different techniques used to diagnosis portal hypertension?
Imaging:
- Duplex doppler ultrasonography
- Provides information on the direction and velocity of portal flow
- MRI and CT are not used.
Endoscope
- Standard diagnostic approach with acute gastrointestinal haemorrhage
- May show bleeding as the varices (common symptom of portal hypertension) are very fragile and prone to bleeding.
- Varices of the oesophagus is the most common but can include the stomach and duodenum.
What is ascites?
- Presence of excess fluid in the peritoneal cavity
What is the possible treatments for portal hypertension?
Medication
- Hypertension medication e.g. propranolol (beta blocker)
- Vasoperssin
Endoscopic therapy i.e. surgical intervention
- Banding
- Sclerotherpay
- Balloon tamponade
- Shunt
Describe each of the endoscopic therapy for portal hypertension?
Banding
- For oesophageal varices
- Small elastic rings are placed over the suctioned varices.
Sclerotherapy
- Injection of sclerosing agent e.g. sodium morrhuate, into or around the varices.
- Balloon tamponade
- Balloon is inserted into the site of the varices and inflated to compress the varices to prevent bleeding.
Shunt
- Dilation of the portal vein and the insertion of a metal stent
- Stent is dilated to achieve a portal to hepatic vein gradient.
- High level of expertise required
- Useful to patients who have recurrent bleeding
Smooth muscle contractions are essential to gastro-intestinal function for the mixing and propulsion of chyme.
What is a major propulsive movement in the gastro-intestinal tract?
Peristalsis
The liver secretes about 0.5 L of bile each day. This is stored and concentrated in the gall bladder for release during digestion.
Which of the following chemical is released into the bile by the liver and plays a role in digestion in the small intestine?
a. Monoamine oxidase
b. Bilirubin
c. Co-lipase
d. Taurocholic acid
e. Cholesterol
D: Taurocholic acid, is a deliquescent yellowish crystalline bile acid involved in the emulsification of fats
Excessive haemolysis of RBC can result in jaundice.
Which metabolite is primarily increased in this condition?
Unconjugated bilirubin
