The Liver and Gallbladder

Question 1

Where does the majority of the blood supply tot he liver come from?

Answer 1

hepatic portal vein

Question 2

What can the liver do to fructose and galactose?

Answer 2

convert to glucose

Question 3

What is transamination?

Answer 3

transfer of an amino group to a keto acid

Question 4

What is deamination?

Answer 4

removal of an amine group (often to form something such as alpha ketoglutarate which can enter the TCA cycle) and ammonium ion NH4+

Question 5

What happens to the ammonia produced by gut bacteria or deamination?

Answer 5

converted to ammonium (NH4+) and then converted to urea in the liver

Question 6

Where are most of the plasma proteins produced?

Answer 6

Liver

Question 7

Name the main components of blood plasma

Answer 7

albumin, globulins, clotting factors and water

Question 8

What does lipid metabolism involve?

Answer 8

breakdown of triacylglycerol to fatty acids and glycerol

Question 9

What happens to the fatty acids produced by TG breakdown?

Answer 9

fatty acids are converted to acetyl CoA which enters respiration (TCA cycle)

Question 10

What happens to the glycerol produced by TG breakdown?

Answer 10

glycerol is converted to glucose in gluconeogenesis

Question 11

What is the effect of insulin on the liver?

Answer 11

Signals the ‘fed-state’ and causes the promotion of glycogenesis and suppresses gluconeogenesis and accelerates glycolysis by encouraging fatty acid synthesis

Question 12

Outline the three phases of drug metabolism

Answer 12

Phase 1 - modification such as hydroxylation by cytochrome p450
Phase 2 - conjugation
Phase 3 - further modification or excretion

Question 13

What are the 4 main things that the liver can store?

Answer 13

Glycogen, vitamins (A, D and B12), cholesterol and iron

Question 14

Why is cholesterol important in our diet?

Answer 14

forms cell membranes, steroid hormones, skin and bile salts

Question 15

How is iron stored in the liver?

Answer 15

Stores apoferritin as ferritin (reversible) and as haemosiderin (insoluble)

Question 16

Describe the components of the biliary tree

Answer 16

The gall bladder is situated posteriorly to the liver and the liver has a hepatic duct, and the gallbladder has a cystic duct which combine to form the common bile duct. which the travels over the pancreas where it then joins the duodenum at the sphincter of oddi

Question 17

Where is bile modified after secretion?

Answer 17

in the hepatocytes by cholangiocytes where bicarbonate is added

Question 18

What stimulates gall bladder contraction to release bile?

Answer 18

CCK detects fatty acids in the lumen of the duodenum and causes gall bladder contraction and relaxation of sphincter of oddi

Question 19

Describe the composition of bile

Answer 19

90% water but has bile salts, bilirubin, cholesterol, fatty acids, common ions and bicarbonate ions

Question 20

Describe the origin, metabolism and excretion of bilirubin

Answer 20

Red blood cell breakdown in the spleen produces bilirubin which is then bound to albumin and transported in the blood and is conjugated to gluronate and egested in the faeces

Question 21

What is jaundice?

Answer 21

yellowing of the skin and sclera due to an excess of bilirubin

Question 22

What happens in liver failure?

Answer 22

hypoglycaemia, impaired clotting, reduced albumin, jaundice and hyperammonaemia