L6 Liver Physiology, Bile and Jaundice

Question 1

Functions of the Liver?

Answer 1

Removal/Detoxification and First Pass metabolism of Orally Administered Drugs

Storage:

• Glycogen
• Triglycerides
• Iron, Copper
• Fat Soluble Vitamins

Synthesis of:

• Albumin
• Transport Proteins
• Coagulation Factors
• Protease Inhibitors (Anti-Trypsin/Anti-Thrombin)
• Bile

Question 2

Blood supply to liver?

Why is this?

Answer 2

Majority from Hepatic Portal Vein (75%)

Hepatic Artery (25%)

Portal vein oxygenation can decrease with increasing GIT activity & O2 demand, Hepatic Supply much more consistent

Question 3

Capilary Beds of Liver?

Answer 3

Capillary Bed 1 drains contents of the intestinal tract through the Portal Vein to the liver

Capillary Bed 2 consists of Sinusoids within the liver

Question 4

Cell of liver responsible for bile secretion and motility?

Answer 4

Cholangiocytes

Question 4

Cell of liver responsible for structure?

Answer 4

Reticuloendothelial cells

Question 5

Liver Macrophages?

Answer 5

Kupffer cells

Question 6

Significance of Endothelial cells of the liver?

Answer 6

They are Fenestrated

Question 7

Most abundant cell of liver?

Answer 7

Hepatocytes

Question 8

Structural unit of the liver?

Answer 8

Hepatic Lobule

Center: Central Vein/Hepatic Vein

Apices:

• Hepatic Portal Vein
• Hepatic Artery
• Bile Duct

Question 9

Functional Unit of the Liver?

Answer 9

Hepatic Acinus

Question 10

Roles of Each Zone of the Hepatic Acinus?

Answer 10

Zone 1 most oxygenated – Oxidative functions

• Gluconeogenesis
• Oxidation of fatty acids

Zone 2– intermediate zone

Zone 3- least well oxygenated

• Glycolysis
• Lipogenesis
• P450 enzyme mediated detoxification

Question 11

When glucagon promotes glycogenolysis, glycogen in __________ will be consumed first

Answer 11

When glucagon promotes glycogenolysis, glycogen in Zone 1 will be consumed first

Question 12

Functions of Bile?

Answer 12

Emulsification of Lipids (Increased Surface area for lipases)

Hormonal Action (GPBA => Perisaltic Control)

Elimination of Waste (Bilirubin congugagted in liver and becomes part of bile)

Question 13

Aqueous component of gall bladder secretion is contributed by ___________________

Answer 13

Aqueous component contributed by bile duct epithelial cells

Question 14

Cholic Acid and Chenodeoxycholic Acid are synthesized by hepatocytes from ___________.

_____________________of bile acids by intestinal bacteria generates Secondary bile acids.

• Cholic Acid => ______________
• Chenodeoxycholic Acid => __________________

Answer 14

Cholic Acid and Chenodeoxycholic Acid are synthesized by hepatocytes from Cholesterol

De-hydroxylation of bile acids by intestinal bacteria generates Secondary bile acids

• Cholic Acid => Deoxycholic Acid
• Chenodeoxycholic Acid => Lithocholic Acid

Question 15

What is found abundantly in Bear Bile but only produced in small amounts in the human colon?

Answer 15

Urso-Deoxycholic Acid (UDCA) has a role in aiding: Liver diseases, Neurodegenerative diseases, Inhibitors of apoptosis

Question 16

Bile enters the duodenum via the ________________

This is the same exit point for __________________

Answer 16

Bile enters the duodenum via the sphincter of Oddi

This is the same exit point for pancreatic secretions

Question 17

___________________of bile acids recovers ~ 90% of the bile acids per cycle

Answer 17

Enterohepatic re-circulation of bile acids recovers ~ 90% of the bile acids per cycle

Question 18

What alters Bile Acid Solubility?

Answer 18

Hydroxylation and Conjugation

• Conjugation increases the water solubility of bile salts rendering them relatively impermeable to the duodenum-> accumulation in the lumen

Question 19

Bile acids are re-absorbed in the _____________ via specific transporters

Answer 19

Bile acids are re-absorbed in the terminal ileum via specific transporters

Question 20

What causes Gall Stones?

Answer 20

Dysregulation of proportions of Cholesterol, phospholipids, and bile salts => Gall Stones!!

Question 21

Consequences of Gall Bladder Removal?

Answer 21

Bile is still produced by the liver however it is more diluted as not concentrated by the gall bladder anymore=> Steatorrhea

Question 22

Removal of Bilirubin?

Answer 22

Bilirubin is a waste product from Heme degradation. It is conjugated in the liver => becomes a component of bile=> degraded in the gut => breakdown products removed in feces

Question 23

Serum Bilirubin for classification of Jaundice?

Answer 23

Unconjugated Serum Bilirubin > 2 mg% is Jaundice

Question 24

Classifications of Jaundice?

Answer 24

Prehepatic: Hemolysis (ie. Malaryis) RBCs excessively broken down => excess heme=Excess bilirubin

Hepatic: Hepatitis, Alcoholic Liver Syndrome (Damage to the liver from alcohol/steroids)

Post hepatic: Interruption of bile drainage (ie. Gallstones)

Question 25

Regulation of Bile Secretion and Gall Bladder Contraction?

Answer 25

Gastric phase: Vagus stimulated by gastric distension => GB emptying

Intestinal phase

• Presence of acid in duodenum => Secretin => Ductal epithelial cells produce bicarb-rich secretion
• Presence of fat in the duodenum => CCK => Stimulation of contraction of GB