Liver and Biliary System

Question 1

1. Where is the transpyloric plane?

2. what does it transect?

Answer 1

1. line found half way between the sternal notch and the pubic symphysis (approx one hands width below xiphoid process)
2. pylorus, pancreatic neck, duodenal-jejunal flexture and hila of kidneys

Question 2

1. which regions are the liver found in?
2. what does the liver lie behind?
3. what does the liver lie inferior to?

Answer 2

1. upper right quadrant
   right hypochondriac/epigastric
2. costal margin
3. diaphragm

Question 3

1. How does the bare area and falciform ligament form during development?
2. what connects the liver to the stomach?
3. what ligament surrounds the bare area?

Answer 3

1. liver is initially attached to the abdominal walls by the dorsal mesogastrum and ventral mesogastrum.
   The foregut rotates to move the liver into its location. As it does so, the liver obliterates the ventral peritoneum which forms the bare area. It is still attached to the anterior abdominal wall by the ventral mesogastrum, whoch forms the falciform ligament in the adult.
2. lesser omentum
3. coronary ligament

Question 4

1. what is the blood supply of the liver?
2. describe the difference between the anatomical and physiological lobes of the liver
3. what is the lymphatic drainage of the liver?

Answer 4

1. hepatic artery proper (which divides into the L and R hepatic arteries as it enters the liver
   hepatic portal vein, carrying nutrient rich blood from the intestines
   hepatic vein - carries blood back to the heart
2. anatomically, the ligament of teres separates the left and right lobes. The caudate and quadrate lobes are anatomically part of the right lobe
   physiologically, the branch of the left hepatic artery supplies the caudate and quadrate lobes, making it physiologically part of the left lobe
3. anterior surface drains into phrenic lymph nodes. Posterior surface drains into hepatic lymph nodes

Question 5

1. what is the subphrenic recess?
2. what is the hepatorenal recess?
3. what is the clinical significance of the hepatorenal recess?

Answer 5

1. the gap between the liver and the abdominal wall/diaphragm
2. gap between liver and kidney that only exists on the LHS
3. this is the deepest part of the body when a patient is supine. Injury to any part of the abdominal cavity can lead down to the pouch of Morrison (aka hepatorenal recess), thus fluid can accumulate here

Question 6

ANTERIOR SURFACE OF LIVER

1. what ligament divides the liver into L and R lobes?
2. what is the ligamentum teres?
3. what does the falciform ligament split into superiorly?
4. which lobe is bigger?

POSTERIOR SURFACE

5. which lobe is superior and inferior?
6. which ligament surrounds the bare area? What is the function of this ligament?

INFERIOR SURFACE

7. the fissure for what ligament can be found inferiorly?
8. Which structures form the portal triad?

Answer 6

1. falciform ligament
2. embryological derivative of foetal circulation. Continuation of falciform ligament inferiorly
3. coronary ligament
4. right
5. caudate superior; quadrate inferior
6. coronary ligament. Attaches the liver to the diaphragm
7. ligament venosum
8. Hepatic artery proper, hepatic portal vein and common bile duct

Question 7

1. what is the role of the pancreas?
   a) exocrine
   b) endocrine
2. Name the 3 parts of the pancreas
3. what shape is the ucinate process? What is it anatomically associated with?
4. what does the pancreatic duct join with and where does it enter the intestine?
5. what is the arterial supply of the pancreas?

Answer 7

1a) secretion of digestive enzymes
1b) blood sugar control and metabolism

2. head, body, tail
3. hook shape. It hooks around the superior mesenteric vessels
4. joins with the common bile duct to form the hepatopancreatic ampulla of vater which enters the duodenum at the major duodenal papilla
5. gastroduodenal artery, splenic artery and superior mesenteric artery

Question 8

1. what is the spleen closely associated with?
2. is it normally palpable?
3. what is the function of the spleen?
4. what is the embryonic origin of the spleen?
5. what region is the spleen found in?
6. what is its diaphragmatic surface associated with?
7. what is its visceral surface associated with?
8. what is the arterial supply of the spleen?

Answer 8

1. stomach and tail of pancreas
2. no
3. filter and store RBCs. Secondary Lymphoid Tissue
4. mesodermal
5. left hypochondriac
6. diaphragm and ribs 9-11
7. stomach, colic flexture of the large intestine and right kidney.
8. splenic artery

Question 9

1. on what surface of the liver does the gall bladder lie?
2. what are the 4 regions of the gall bladder?
3. what is its function?
4. Describe the biliary tree

Answer 9

1. posterior
2. fundus, body, neck and cystic duct
3. to store and concentrate bile
4. right and left hepatic ducts anastomose to form the common hepatic duct
   common hepatic duct and cystic duct of gall bladder anastomose to form the common bile duct
   common bile duct anastomises with the pancreatic duct.

Question 10

1. what are hepatic laminae?
2. what are bile canaliculi?
3. what are hepatic sinusoids?

Answer 10

1. arrangements of hepatocytes that are 1 cell thick, bordered on each side by a hepatic sinusoid
2. small ducts between hepatocytes that collect bile.
3. highly permeable capillaries between rows of hepatocytes. They recieve blood from the hepatic artery and hepatic portal vein, and converge on the central vein which drains into the IVC

Question 11

Describe the 6 major functions of the liver

Answer 11

1. carbohydrate metabolism
2. lipid metabolism
3. protein metabolism
4. breakdown of erythrocytes
5. catabolism of hormones, toxins, alcohol and drugs
6. production of bile

Question 12

Describe the 3 processes that the liver performs to maintain glucose homeostasis

Answer 12

1. GLYCOGENESIS - formation of glycogen (and triglycerides) which is stored in the liver
2. GLUCONEOGENESIS - production of new glucose from amino acids, triglycerides and lactic acid
3. GLYCOGENOLYSIS - breakdown of glycogen

Question 13

1. Name the 5 roles that the liver performs relating to lipid metabolism
2. how is cholesterol synthesised?

Answer 13

1. storage of triglycerides
   metabolism of fatty acids to produce ATP
   synthesis of lipoprotiens
   synthesis of fatty acids and cholesterol
   synthesis of bile salts from cholesterol
2. from Acetyl CoA. HMG-CoA acts on acetyl CoA. This enzyme is inhibited by statins.

Question 14

How does the liver have a role in protein metabolism? (2)

Answer 14

• synthesis of most plasma proteins
• urea formation - hepatocytes deaminate amino acids so that they can be used to make ATP. This results in ammonia which is toxic, thus converted to urea

Question 15

1. what are the specialist macrophages that break down erythrocytes in the liver?
2. how is Haemoglobin broken down?

Answer 15

1. Kupffer Cells
2. broken down into globin and haem.
   globin is broken down further into amino acids
   haem is broken down into iron and billirubin, which is secreted with bile

Question 16

1. What do phase 1 catabolism reactions involve?

2. what do phase 2 catabolism reactions involve?

Answer 16

1. cytochrome P450 enzymes

2. conjugation with glucuronide

Question 17

Name 4 components of bile

Answer 17

1. bile salts - produced from cholesterol
2. cholesterol and phospholipids
3. bilirubin - breakdown product of haem
4. proteins, fatty acids and ions

Question 18

1. what are lipoproteins?
2. how do the following transport fats?
   a) chylomicrons
   b) VLDLs
   c) LDLs
   d) HDLs

Answer 18

1. spherical particles composed of proteins and fats. They function to transport lipids in the blood

2a) from intestine, around the body
2b) transport triglycerides synthesised in liver to adipose tissue for storage
2c) transport cholesterol from liver for use in the body
2d) remove excess cholesterol from body and transport it to liver for elimination

Question 19

1. What is prehepatic jaundice caused by?
2. what is hepatic jaundice caused by?
3. what is post-hepatic jaundice caused by?
4. is bilirubin present or absent from the urine in the above types of jaundice?

Answer 19

1. increased breakdown of RBCs
2. liver disease such as hepatitis or hepatoma
3. obstruction of gall bladder/bile duct
4. absent in pre-hepatic and hepatic jaundice. present in post-hepatic jaundice

Question 20

1. Name the 4 substances examined in liver function tests and why they are used

Answer 20

1. alanine aminotransferase (ALT)
2. Asperate Aminotransferase (AST)
   * both are enzymes present in the cytosol of hepatocytes. Raised levels indicate hepatocyte death
3. albumin - normally synthesised by the liver; less albumin will be synthesised by diseased livers
4. Pro-thrombin time - liver is responsible for synthesising clotting factors; diseased livers will synthesise less clotting factors therefore clotting time will be increased

Question 21

1. what are the primary bile acids and how are they produced?
2. How are the primary bile salts produced?
3. How are the secondary bile salts produced?
4. Name 4 functions of bile

Answer 21

1. cholic acid and chenodeoxycholic acid. They are synthesised from cholesterol in the liver
2. in the liver, bile acids are conjugated with glycine or taurine, to produce the bile salts
3. Secondary bile acids are produced by fermentation in the intestine. They are reabsorbed and transported back to the liver where they are conjugated once again with glycine and taurine
4. • neutralisation of stomach acid
     - immune role (carries IgA)
     - emulsification
     - route of excretion for bilirubin

Question 22

1. what is the name given to collectively to the cells that produce billirubin from haem?
2. what organs make up this system?
3. Describe the pathway of billirubin production and elimination

Answer 22

1. reticuloendothelial system
2. liver and spleen
3. haem is converted to billiverdin (by haem oxygenase) and then unconjugated billirubin (by bilirubin reductase)
   unconjugated bilirubin travels in blood bound to albumin. It is removed from circulation via hepatic sinusoids
   glucuronyl bilirubin transferase conjugates bilirubin. Conjugated bilirubin is secreted into bile
   in intestine, conjugated bilirubin is broken down into urobilinogen
   urobilinogen is either broken down further into secrobilin or reabsorbed into blood and excreted in urine as urobilin.

Question 23

1. What is cholelithiasis?
2. what is choledocholithiasis?
3. what leads to the production of gall stones?
4. which group of people are at risk and why?
5. describe 4 signs of choledocholithiasis

Answer 23

1. presence of gall stones in the gall bladder
2. presence of gall stones in the bile duct
3. crystalisation of cholesterol, if bile contains excessive cholesterol or insufficient bile salts
4. females (fat, forty, fertile)
   - cholesterol is a precursor for oestrogen; high levels of oestrogen require high levels of cholesterol, making cholesterol supersaturation of bile more likely
5. conjugated bilirubin in urine (as very little bile can enter the duodenum, causing a backlog)
   dark urine
   jaundice
   clear coloured stool

Question 24

Describe how the following act as lipid lowering drugs:

1. statins
2. fibrates
3. bile binding resins
4. Ezetimibe

Answer 24

1. competitively antagonise HMG-CoA, the enzyme that is involved in cholesterol biosynthesis
2. increase the transcription of genes encoding lipoprotein lipase, thus acting to reduce the amount of circulating VLDLs and LDLs
3. sequester bile acids in the small intestine. As a result, there is increased bile excretion, and forces the liver to produce more bile acids from cholesterole
4. inhibits the absorption of cholesterol from the duodenum