Physiology of the Liver, Gall Bladder, and Pancreas

Question 1

What are the two main functions of the pancreas?

Answer 1

Endocrine and exocrine (90% exocrine).

Question 2

What are the components of pancreatic fluid?

Answer 2

Aqueous (HCO₃⁻, water) and enzymatic (amylase, lipase, proteases)

Question 3

Which pancreatic enzymes are secreted in active and inactive form?

Answer 3

• Active: Amylase and lipase
• Inactive: Proteases (e.g., trypsinogen).

Question 4

What do acinar and centroacinar cells secrete?

Answer 4

Acinar: enzymes
Centroacinar: water and HCO₃⁻

Question 5

What ions are in pancreatic juice?

Answer 5

Na⁺, Cl⁻, K⁺, and HCO₃⁻

Question 6

What type of cells are absent in the pancreas but present in salivary glands?

Answer 6

Myoepithelial cells

Question 7

What transporter is on the apical membrane and basolateral membrane of duct cells?

Answer 7

• apical: HCO₃⁻/Cl⁻ exchanger and CFTR channel
• basolateral: Na+/K+ ATPase, Na +/H+ exchanger and others

Question 8

What is the net effect of pancreatic secretion?

Answer 8

Secretion of HCO₃⁻ and absorption of H⁺, making venous blood acidic

Question 9

What is the ion composition of low-flow and high-flow pancreatic juice?

Answer 9

• low: Na⁺, K⁺, and Cl⁻
• high: Na +, K+, and HCO3-

Question 10

How is the release of enzymes from the pancreas from digestion in the duodenum triggered?

Answer 10

Peptides, amino acids, fatty acids → CCK → increases intracellular Ca²⁺ of acinar cells → enzyme exocytosis (pancreatic lipase)

Question 11

How are H+ ions in the chyme neutralized by
the pancreas?

Answer 11

H⁺ ions → Secretin → Increases cAMP → secretion of Na⁺ and HCO₃⁻

Question 12

What potentiates CCK action in the pancreas?

Answer 12

Acetylcholine via M3 receptors

Question 13

What condition results from premature enzyme activation?

Answer 13

Pancreatitis

Question 14

What are the 3 phases of pancreatic secretion?

Answer 14

• Cephalic
• Gastric
• Intestinal

Question 15

Which phase contributes most to pancreatic secretion and what inhibits pancreatic secretions from the distal intestines?

Answer 15

• Intestinal phase
• Peptide YY and somatostatin inhibit the distal portion of the intestines

Question 16

What happens to pancreatic ducts in cystic fibrosis?

Answer 16

CFTR defect → thick fluid blocks ducts.

Question 17

What are the effects of pancreatic duct blockage in CF?

Answer 17

Malabsorption, bacterial overgrowth, insufficiency

Question 18

What is enterohepatic circulation?

Answer 18

Liver receives blood via celiac artery and portal vein and makes albumin, urea, cholesterol, bile acids, and detoxifies substances

Question 19

How is bile secreted and how does it reach the duodenum?

Answer 19

Bile flows from hepatocytes through ducts and sphincter of Oddi into the duodenum. CCK relaxes Oddi to release bile

Question 20

How does bile flow change during meals versus between meals?

Answer 20

Flow depends on resistance between gallbladder and Oddi. Bile stored between meals, released during meals.

Question 21

What stimulates gallbladder contraction and sphincter of Oddi relaxation?

Answer 21

• Fat triggers CCK → gallbladder contracts
• VIP and NO relax Oddi
• CCK also stimulates vagal efferents

Question 22

What components make up the biliary system and how is bile recycled?

Answer 22

• Liver, ducts, duodenum, and portal circulation form the system
• Bile salts are synthesized and recycled

Question 23

How do hepatocytes secrete bile acids via dependent and independent pathways?

Answer 23

Dependent: bile salts from recycled or de novo sources draw water
Independent: secretin stimulates HCO₃⁻ and water secretion

Question 24

What is the composition of bile and how is it concentrated?

Answer 24

Mainly bile salts, bilirubin, cholesterol, lecithin. Gallbladder concentrates bile by reabsorbing water/electrolytes.

Question 25

What are primary and secondary bile acids and how are bile salts formed?

Answer 25

- Primary acids: cholic and chenodeoxycholic - Secondary: deoxycholic, lithocholic - Conjugated → bile salts (amphipathic)

Question 26

How do bile salts and micelles aid in fat digestion and vitamin absorption?

Answer 26

Bile salts emulsify fats into micelles for absorption - Needed for absorbing fat-soluble vitamins (A, D, E, K)

Question 27

How are bile salts recycled and what happens if the ileum is removed?

Answer 27

Reabsorbed in the ileum via Na⁺ cotransporters - Ileal resection impairs recycling → steatorrhea

Question 28

What transport systems recover bile salts and how is synthesis regulated?

Answer 28

- 85–97% recovery via OAT system - synthesis adjusted by feedback → key enzyme: cholesterol 7α-hydroxylase.

Question 29

What are the sources and pathways of bile pigment metabolism?

Answer 29

- Biliverdin and bilirubin from hemoglobin - Liver conjugates bilirubin → to urobilinogen → urobilin/stercobilin

Question 30

What causes jaundice and what is kernicterus in infants?

Answer 30

- Excess bilirubin causes yellowing - Infant kernicterus is due to bilirubin crossing immature blood-brain barrier

Question 31

How do gallstones form and what complications can they cause?

Answer 31

- Cholesterol stones form when bile is supersaturated - Gallstones can block ducts → pancreatitis