Liver and the biliary system

Question 1

________ are small biliary channels, between hepatocytes

Answer 1

Bile canaliculi

Question 2

Bile canaliculi drain into_______

list 5

Answer 2

Bile ductules near the portal tract

R and L ducts leave each liver lobe

Common hepatic duct at porta hepatis

Cystic duct connects the Gallbladder to lower end of common bile duct

Drains into small intestine

Question 3

list 4 facts about gallbladder

Answer 3

Small pear-shaped organ attached to the underside of the right lobe

Stores and concentrates XS bile - bile lining epithelial cells absorb salts and water

Storage capacity 35-100 mls

Dietary fats induce the release of cholecystokinin, which triggers gall bladder contraction, expelling bile into intestine

Question 4

_____is the main exocrine secretion of the liver

Answer 4

bile secretion

Question 5

_____is involved in the digestion and absorption of fats

Answer 5

bile

Question 6

_______is a Yellowish-green, viscous, slightly alkaline fluid

Answer 6

bile

Question 7

list 5 components of bile

Answer 7

Water

Bile pigments (bilirubin)

Bile salts (acids)

Phospholipids (mainly lecithin)

Inorganic ions

Question 8

list 6 facts about Bile pigment

Answer 8

Produced by spleen, liver and bone marrow

Excretory products of haem groups

Mainly from breakdown of RBC by kupffer cells

15% from other haems - myoglobin, cytochromes

Haemoglobin broken down to - biliverdin (green/ blue porphyrin) - bilirubin (yellow)

250-300mg bilirubin produced daily

Question 9

Bile pigment (bilirubin) exists in three forms _______,______ and _________

Answer 9

free bilirubin

bound bilirubin and

conjugated bilirubin

Question 10

list 2 facts about Free/bound bilirubin

Answer 10

Lipid soluble, poorly water soluble

Plasma albumin bound, not excretable when bound

Question 11

list 4 facts about Conjugated bilirubin

Answer 11

Conjugated with glucuronic acid - water soluble

Enters intestine, not absorbable from intestine

Hydrolysed by bacteria in terminal ileum

Enterohepatic circulation

Question 12

list 4 facts about cycling processes

Answer 12

A process of absorption, excretion and subsequent reabsorption

A cycling cmpd persists longer in the body than would normally occur

This reduces the overall rate of decline in plasma drug concn

Results in waves in the plasma concn-time profile

Question 13

explain enterohepatic circulation situations (part of cycling processes)

Answer 13

If the drug has been modified by Phase I metabolism before glucuronidation, re-absorption may be blocked. But cycling may occur with Phase I metabolites

Question 14

give a good example of enterohepatic circulation.

Answer 14

in digoxin:

Excreted in the bile as an O-glucuronide

Metabolised back to digoxin by lower GIT bacteria - glucuronic acid is released

Digoxin is reabsorbed

Greater than 75% of the drug re-circulates

Question 15

list 4 facts about bile salts.

Answer 15

Synthesised in hepatocytes from cholesterol

Form salts in solution which aid absorption of fats by emulsification

Activates lipase

Undergoes enterohepatic circulation

Question 16

list 2 primary bile acids.

Answer 16

Cholic acid – reabsorbed

Chenodeoxycholic acid - reabsorbed

Question 17

bile salts are conjugated with _______or______

Answer 17

glycine or taurine

Question 18

Bile salts are Converted to secondary bile acids __________

Answer 18

intestinal bacteria

Question 19

list one secondary bile acids

Answer 19

Deoxycholic acid