4- Liver

Question 1

What are 3 general functions of the liver

Answer 1

Metabolic and catabolic functions: synthesis and utilization of carbohydrates, lipids and proteins.
Secretory and excretory functions: synthesis and secretion of bile and waste products
Detoxification and immunological functions: breakdown of ingested pathogens and processing of drugs

Question 2

3 functions of bile

Answer 2

Emulsification and absorption of fat: to increase surface area for lipase activity
Cholesterol homeostasis: excreting excess as needed
Toxin excretion: endogenous (e.g. bilirubin) and exogenous (e.g. drugs)

Question 3

Liver anatomy

Answer 3

The liver can be split into two lobes (right and left), which are separated by the falciform ligament.

The liver receives a dual blood supply, which reflects its important metabolic, secretary and immunological functions. The main perfusing vessels are the hepatic artery (blood from heart) and hepatic portal vein (blood from the gut).

Question 4

Why can liver survive if chunks are missing

Answer 4

Each lobe can be further separated into discrete segments, with their own anatomical borders, but more crucially, with an independent blood supply and bile drainage. Because of this, it is quite possible to have severe damage in one part of the liver without affecting other parts. The subsections are numbered from I to VIII (although IV is usually split into upper (a) and lower (b) subsegments).

Each subsection drains into its own vein, with those subsequently draining into the left, middle and right hepatic veins before joining the vena cava

Question 5

What is a hepatic lobule

Answer 5

Hexagon
Each corner has portal triad that links with 3 other lobules
Central vein in middle collects blood
Rows of hepatocytes

Question 6

What makes up the portal triad

Answer 6

Bile duct
Hepatic portal vein branch- delivers nutrients+ toxins
Hepatic portal artery branch- delivers o2 to hepatocytes

Question 7

What is a hepatic acinus

Answer 7

Functional unit of the liver

Made of 2 1/6 of a lobule, sharing 2 portal triads

Question 8

What are the 3 zones of the acinus

Answer 8

1- High o2 + high toxin risk
2- med 02 + med toxins
3- low o2 + low toxins

Question 9

What are Kupffer cells

Answer 9

Sinusoidal macrophages
Stellate shaped
Phagocytise pathogens+ destroy toxins in portal blood
Secrete cytokines
Abundant
Attached to endothelium

Question 10

Describe the endothelium in the liver

Answer 10

Fenestrated

Wide capillaries so blood moves slowly

Question 11

What are hepatic stellate cells

Answer 11

Quiescent cells
Store vit A
Become fibroblasts when activated by liver damage and deposite collagen
Found in space of disse, below capillary

Question 12

5 points about hepatocytes

Answer 12

Cuboidal
80% of liver mass
Synthesis e.g. albumin, clotting factors
Drug metabolism 
Receive nutrients

Question 13

What’s a cholangiocyte

Answer 13

Secrete bicarbonate and water to form bile

Question 14

What is the structure of a billary tree

Answer 14

biliary tree starts in millions of bile canaliculi These canaliculi then drain into small ductules, which drain into small bile ducts.
Then coalesce into larger bile ducts for each liver segment.
These merge together to form the right and left hepatic ducts, which converge to form the common hepatic duct. Connected to this duct is the cystic duct, which connects the gall bladder.

Question 15

How is the common bile duct formed and where does it go

Answer 15

The merging of the common hepatic duct and the cystic duct forms the common bile duct, which extends towards the duodenum. At its distal end the pancreatic duct joins and the vessel is then called the ampulla of Vater, which opens up into the medial wall of the duodenum at the duodenal papilla.

Question 16

What is the enterohepatic circulation

Answer 16

substances can cycle between the gut and liver by continuous reabsorption in the gut, carriage in portal blood to liver, and hepatocyte secretion into bile canaliculi, to be secreted (in bile) via the common bile duct.

Question 17

Give a good+ bad example of the enterohepatic circulation

Answer 17

recycling of bile salts (sometimes so efficiently that the same salts can be used twice to digest the same meal). This improves the digestion and absorption of fats.

One way the liver processes some drugs is to excrete them via bile (to avoid them going into circulation), and eventually the faeces. However they may get reabsorbed in the small intestine and re-enter the portal circulation cyclically, significantly increasing their half-life.