Midterm paper

MODULE 10 LO5 Digestive Functions of Liver, Gallbladder and Pancreas Dr. Lisa Brinn [email protected]

click here for video link

Liver • Largest visceral organ • More than 200 different functions • Essential metabolic and synthetic services

A. Metabolic regulation B. Hematological regulation C. Bile synthesis and secretion

• Other functions: v Storage of glycogen and lipid reserves v Maintenance of normal blood glucose, amino acid, and fatty acid

concentrations v Inactivation of toxins v Storage of iron reserves v Synthesis of the inactive hormone angiotensinogen

Liver Anatomy

Superior view

Inferior view

Anterior view

Liver Histological Organization Liver Lobule

Posterior view Anterior view

A. Metabolic Regulation • Represents a central clearinghouse • Regulates levels of:

v Carbohydrates v Lipids v Amino acids

• Hepatic portal system → liver • Hepatocytes

v Monitor circulating levels of metabolites v Adjust if necessary v Removal of toxins

o Inactivated o Stored o Excreted

v Absorption and storage of fat-soluble vitamins

B. Hematological Regulation • Largest blood reservoir in body

v Receives 25% of CO • Kupffer cells

v RBCs o Old and damaged cells get removed

v Removal of: o Cellular debris o Pathogens

• Hepatocytes v Synthesize plasma proteins

o Blood osmotic concentration o Nutrient transport o Clotting and complement systems

C. Bile Synthesis and Secretion • Synthesized

v Hepatocytes • Stored

v Gallbladder • Excreted

v Duodenum • Composition:

v Water v Ions v Bilirubin v Bile salts + lipids in chyme = break down into fatty acids → absorption

Dilution and buffering of acids in chyme

Gallbladder

Inferior view

• Functions v Bile storage (cystic duct) v Bile modification

o Water is absorbed o Concentration of bile salts and other components

• Bile ejection v Cholecystokinin

o Presence of: Ø Lipids Ø Proteins ↓ Ø Relaxation of sphincter of Oddi Ø Gallbladder contraction

Lab Models

Inferior view

Posterior view

Posterior view

Pancreas Anterior view

• Lies posterior to the stomach • Pancreatic acini

v Secrete pancreatic juice o Water + ions + pancreatic digestive enzymes

• Pancreatic enzymes v Lipases – digest lipids v Carbohydrase – digest sugars and starches v Nucleases – attach nucleic acids v Proteolytic enzymes – break proteins apart

o Proteinases – large protein complexes o Peptidases - small peptide chains → amino acids

• Regulation of Pancreatic Secretion v Hormonal instructions from duodenum

o Secretin – acidic chyme Ø Triggers → buffers

o CCK – chyme in stomach and duodenum Ø Triggers → pancreatic juice