PSC1002/L28 Pancreas & Bile

Question 1

Describe the fluid and electrolyte balance of pancreatic juice. (3)

Answer 1

Wash out enzymes
Alkaline (pH8) to neutralise gastric acid in duodenum
Primary secretion from acinar cells
Modified to HCO3-rich juice by duct cells

Question 2

What is the composition of pancreatic juice?

Answer 2

Enzymes
Fluid & electrolytes

Question 3

Give 3 types of pancreatic enzymes.

Answer 3

Amylolytic
Proteolytic
Lipolytic
Nucleolytic

Question 4

What are pancreatic proteases secreted as?

Answer 4

Zymogens

Question 5

How are zymogens activated?

Answer 5

Enterokinase in intestine
Trypsin can auto-activate

Question 6

What is secreted by acinar cells?

Answer 6

Primary secretion of isotonic NaCl

Question 7

What is secreted by the duct? (2)

Answer 7

HCO3- secretion
Isotonic via apical Cl-/HCO3- exchange & CFTR Cl- channels

Question 8

Describe cystic fibrosis. (5)

Answer 8

Absence of CTFR channels
Lack of fluid secretion
Lack of washout of enzymes
Damage to pancreas
Poor nutrition

Question 9

Describe the release of secretin. (3)

Answer 9

From duodenal S cells
Release stimulated by acid
Increases HCO3- secretion

Question 10

Describe cholecystokinin-Pancreozymin (CCK) release. (4)

Answer 10

From duodenal I cells
Release stimulated by fat and protein
Stimulates gall bladder contraction
Stimulates pancreatic enzyme secretion

Question 11

Describe the purpose of neural (vagus) pancreatic secretion control.

Answer 11

Stimulates both acinar and duct cells

Question 12

Give 2 functions of bile.

Answer 12

Elimination of waste products
Promotion of lipid digestion and absorption

Question 13

Give 3 waste products eliminated in bile.

Answer 13

Cholestrol
Bile pigments
Minerals
Lipophilic drugs and metabolites
Heavy metals

Question 14

Where is bile secreted into?

Answer 14

Canaliculi

Question 15

What do the bile ducts secrete?

Answer 15

HCO3-rich fluid

Question 16

How does bile enter the duodenum?

Answer 16

By common bile duct

Question 17

Describe the composition of bile. (2)

Answer 17

Biliary lipids
Bile pigments

Question 18

What is the function of bile acids?

Answer 18

Keep cholestrol in solution

Question 19

Describe primary bile acids. (2)

Answer 19

Liver synthesis from cholestrol
E.g., cholic acid (cholate)

Question 20

Describe secondary bile acids. (2)

Answer 20

Modification by intestinal bacteria (dehydroxylation)
E.g., deoxycholate

Question 21

Describe conjugation of bile acids. (3)

Answer 21

To amino acids (glycine or taurine)
Increases solubility
E.g., taurocholate

Question 22

Describe enterohepatic circulation of bile acids. (6)

Answer 22

Synthesis of primary bile acids in liver
Secretion into duodenum in bile
Involved in lipid digestion/absorption
Reabsorption in terminal ileum
Recirculation through hepatic portal vein into liver
Taken up by liver and secreted into bile

Question 23

What are bile salts coating lipids called?

Answer 23

Emulsions

Question 24

What is the purpose of emulsification of dietary lipids?

Answer 24

Increases surface area exposed to lipases and promotes digestion

Question 25

Give 2 functions of the gall bladder.

Answer 25

Concentrates bile x20
Absorbs electrolytes and water

Question 26

Give 3 ways in which bile secretion is controlled.

Answer 26

Bile acid-dependent
Ductal
Gall bladder contraction

Question 27

How do gallstones occur? (2)

Answer 27

Inability to keep cholestrol in solution
Super-saturation with cholestrol