Bile and Biliary system

Question 1

What effect do bile acids in the blood have on the biliary system

Answer 1

Bile acids via blood stimulate parenchymal secretion

Question 2

What effect does secretin in the blood have on the biliary system?

Answer 2

Causes liver ductal secretion

Question 3

What effect does cholecystokinin (CCK) in the blood have on the biliary system?

Answer 3

Gall bladder contraction

Relaxation of the sphincter of Oddi

Question 4

What effect does the vagal stimulation have on the gallbladder

Answer 4

Causes a weak contraction

Question 5

What is the relationship between bile flow and liver blood flow

Answer 5

They are independent, at high pO2.

Bile flow is an active process requiring energy

Question 6

How is biliary pressure affected by blood flow

Answer 6

They are independent

Question 7

What joins to make the common hepatic duct

Answer 7

the right and left hepatic ducts

Question 8

What do the right and left hepatic duct join to form

Answer 8

the common hepatic duct

Question 9

What do the common hepatic duct and the cystic duct join to form

Answer 9

the common bile duct

Question 10

What joins with the common bile dict and where

Answer 10

The pancreatic duct at the sphincter of oddi at the ampulla of vater

Question 11

Why is water reabsorbed in the gallbladder

Answer 11

so bile salts are concentrated

Question 12

Describe the physiology of the reabsorption of water in the gallbladder

Answer 12

Paracellular movt of water by osmotic gradient
Grad. produced by movement of ions into interstitial space
Na+:H+ pump in apical membrane moves protons into lumen and Na+ into cell. Then a 3Na+:2K+ ATPase pump in basolateral membrane brings 3Na+ into interstitial space and 2K+ into cell.
K+ then diffuses back into interstitial space through an ion channel

Chloride ions are pumped in to cell by pump in apical membrane in favour of HCO3- which is pumped out of the cell into the lumen. Then Cl- diffuses out of the cell into the interstitial space.

Question 13

How are glycerol, short and medium chain fatty acids absorbed?

Answer 13

They pass through the enterocyte and enter the blood capillaries due to their small size

Question 14

What happens to emulsion droplets arriving in the duodenum from the stomach?

Answer 14

Pancreatic lipases, biliary bile salts, lecithin and cholesterol adsorb to their surface.

Question 15

What effect does bile salts have on multilamellar micelles

Answer 15

Bile salts transform multilamellar micelles into unilamellar micelles and then into mixed micelles which contain bile salts and mixed lipids

Question 16

Where and how are bile salts reabsorbed?

Answer 16

In the distal ileum by active transport; and passively throughout the small intestine

Question 17

What happens to lipids after they have been absorbed in enterocytes?

Answer 17

They are reesterified and apoproteins are added producing chylomicrons which are exported via lacteals into the lymph

Question 18

Where are apoproteins produced and where are they added to a lipid?

Answer 18

Produced in the RER and added in the SER

Question 19

Where does the lymph flow to get back into circulation after absorption of chylomicrons?

Answer 19

To the thoracic duct to enter the blood via left subclavian vein

Question 20

Why does bile secretion require oxygen

Answer 20

Active process

Question 21

Is bile secretion dependent/independant of biliary blood flow

Answer 21

independent

Question 22

What is the blood conc of bilirubin which may cause jaundice

Answer 22

> 18mg/ml

Question 23

Why can glycerol pass through enterocyte

Answer 23

Small size

Question 24

Why do short and medium chain fatty acids diffuse efficiently into enterocytes

Answer 24

Soluble in extracellular water layer

Question 25

Why do fatty acids leave the micelle near the cell

Answer 25

Low pH @ brush border

Question 26

How do fatty acids which have left micelles get absorbed into the enterocyte

Answer 26

non-ionic diffusion

or collision and incorporation into membrane

Question 27

Describe how bilirubin is handled in the body

Answer 27

Reabsorbed via bilitranslocase or via OATP-1 (Cl- exchange)

Blilrubin then moved to ER where glucaronic acid is added to produce bilirubin-mono/di-gluconaride

Then that is converted to urobiligen (excreted from kidneys as urobilin) and then converted to sterobilin (excreted in faeces)

Question 28

What are the causes of gallstones

Answer 28

Too much reabsorption of water from bile
Too much reabsorption of bile acids from bile
Too much cholesterol in bile
Inflammation of epithelium