Session 6 - Liver, Biliary Tree + Pancreas

Question 1

How is the acidic nature of the chyme leaving the stomach corrected?

Answer 1

• HCO3- secreted by pancreas, liver and duodenal mucosa
• neutralises acidic chyme
• the HCO3- is produced during the production of stomach acid

Question 2

How is the hypertonic nature of chyme leaving the stomach corrected?

Answer 2

Osmotic movement of water into the duodenum across its wall

Question 3

What components make up the bile acid dependent part of bile?

Answer 3

• Bile acids (salts)
• Cholesterol
• Bile pigments (bilirubin)

Question 4

What makes up the bile acid independent part of bile?

Answer 4

Alkaline juice

Question 5

Describe the functional unit of the liver

Answer 5

• Loubule surrounding a central vein
• Hexagonal shape with Portal triad vessels at each point
• Blood from vein and artery flows towards central vein
• Bile formed in canaliculi flows towards periphery into bile ducts

Question 6

What effect does CCK have on the gall bladder?

Answer 6

Causes it to contract, releasing bile into duodenum in response to gastric emptying

Question 7

What causes the release of alkali front he liver and pancreas?

Answer 7

Secretin

Question 8

Where can bile acids be reabsorbed?

Why is this important?

Answer 8

Terminal Ileum
By this point the bile acids have done there job in ensuring absorption of fats and the reabsorption means that we don’t have to make as much as most are recycled

Question 9

Name some secretions of the exocrine pancreas

Answer 9

Trypsinogen 
Chymotrypsin 
Elastase 
Carboxypeptidase 
Amylases 
Lipases

Question 10

How are the acinar cells of the pancreas stimulated?

Answer 10

• stimulated by CCK
• released from duodenal cells
• these are stimulated by hypertonicity, fats and small peptides

Question 11

How are the ductal cells of the pancreas stimulated?

Answer 11

• Stimulated by secretin
• which is released from jejunal cells
• which are stimulated in response to a low pH

Question 12

Describe the process that causes large fat globules to from chylomicrons

Answer 12

• bile acids emulsify fats into small micelles
• this increases SA for lipase action (cleave FA from glycerol)
• micelles move into unstirred layer where FAs are slowly released into epithelial cells
• once in cells they are reconstituted as TAGs + re-expelled into the GI

Question 13

By which system are fats absorbed in the GI tract?

Answer 13

The lymphatic system

Question 14

Describe Steatorrhoea

Answer 14

• if bile acids or lipases are not secreted fat will appear in faeces
• stools will be pale, float and smell foul