LECTURE 6 (Liver)

Question 1

What are the different functions of the Liver?

Answer 1

• Secretion of bile salts
• Metabolic processing of carbohydrates, proteins and lipids
• Detoxifying or degrading body wastes and hormones
• Synthesising plasma proteins
• Storing glycogen, fats, iron, copper and many vitamins
• Activating Vitamin D
• Secreting the hormones THROMBOPOEITIN, HEPCIDIN and INSULIN-LIKE GROWTH FACTOR-I
• Excreting cholesterol and bilirubin
• Removing bacteria and worn-out red blood cells

Question 2

What are the two types of cells found in the liver?

Answer 2

• Hepatocytes = perform a wide variety of metabolic and secretory tasks
• Kupffer cells = phagocytic activity

Question 3

The liver receives blood from which two sources?

Answer 3

• Hepatic artery = Arterial blood which provides the liver with O2 supply and carries blood-borne metabolites for hepatic processing
• Hepatic portal vein = Venous blood draining the digestive tract

Question 4

Blood leaves the liver via the _________ ______

Answer 4

Hepatic Vein

Question 5

What is the capillary network called that the portal vein breaks up into to permit exchange between the blood and hepatocytes?

Answer 5

Liver sinusoids

Question 6

What does the Hepatic triad consist of?

Answer 6

• Hepatic artery
• Hepatic portal vein
• Bile duct

Question 7

What happens to bile between meals?

Answer 7

The liver continuously secretes bile even between meals -> SPHINCTER OF ODDI prevents bile from entering duodenum except during digestion of meals -> Sphincter is closed -> Bile secreted by liver is diverted back up into GALLBLADDER
-> Bile is stored and concentrated in the gallbladder between meals

Question 8

What are the properties of Bile salts?

Answer 8

• Derivatives of cholesterol
• Actively secreted into bile and eventually enter duodenum
• Reabsorbed into blood by special active-transport mechanisms in the terminal ileum
  [returned by hepatic portal system to liver which re-secretes them into bile = ENTEROHEPATIC CIRCULATION]

Question 9

Why is Colipase secreted along with lipase?

Answer 9

Bile salts increase SA for pancreatic lipase but lipase alone cannot penetrate the layer of bile salts adsorbed on the surface of the small emulsified fat droplets

Question 10

What is the function of Colipase?

Answer 10

Secreted by the pancreas, it displaces some bile salts and lodges at the surface of fat droplets -> Binds to lipase -> Anchors the enzyme to its site of action

Question 11

What is the importance of micelles?

Answer 11

• Water soluble (due to hydrophilic shells)
• Can dissolve water-insoluble substances in their lipid-soluble cores (can transport through water)

Question 12

What is a Choleretic?

Answer 12

Any substance that increases bile secretion

Question 13

What happens when CCK is released?

Answer 13

1) Hormone stimulates contraction of the GALLBLADDER and relaxation of the SPHINCTER OF ODDI
2) Bile is discharged into duodenum -> aids in digestion and absorption of the fat that initiated CCK release

Question 14

What are the different types of Jaundice?

Answer 14

• Pre-hepatic/Hemolytic jaundice = excessive breakdown of RBCs from excessive bilirubin
• Hepatic jaundice = when liver is diseased and cannot deal with normal load of bilirubin
• Post-hepatic/Obstructive jaundice = bile is obstructed -> bilirubin cannot be eliminated in faeces

Question 15

What is Hepatitis?

Answer 15

An inflammatory disease of the liver that results from viral infection, obesity and exposure to toxic agents

Question 16

What is Cirrhosis?

Answer 16

When damaged hepatocytes are permanently replaced by connective tissue