Topic 55 - Production, functions and regulation of the bile

Question 1

Words to include in bile production

Answer 1

• Gall bladder
• NaCl
• Water
• NaHCO₃^-
• Parenchyma cells of the liver
  
  • Bile salts
  • Cholesterol
  • Phospholipids
  • Bile pigment
• Epithelial cells of the bile canaliculi
• Micelles
  
  • Bile salts
  • Cholesterol
  • Lecithin
    
    • Amphiphatic (hydrophilic + hydrophobic)
• Bile pigment
• Electrolytes (HCO₃^.)

Question 2

Words to include in bile acids

Answer 2

• Cholesterol
• Primary bile acids
  
  • Cholc acids
  • Chenodeoxycholic acid
• Secondary bile acid
  
  • Deoxycholic acid
  • Litocholic acid
• Taurine
  
  • Taurocholic acid
• Glycine
  
  • Glycocholic acid

Question 3

Words to include in functions of the bile

Answer 3

• Emulsifying fat (secretory)
• Metabolic end-product (excretory)
• Antibodies (excretory)
• Enterohepatic circulation
  
  • Ileum
  • Hepatocytes
  • Conjugate
  • Bile
  • Jejunum
  • Liver
  • Bile acid synthesis

Question 4

Words to include in regulation of bile secretion

Answer 4

• Gall bladder
  
  • Na⁺
  • Cl^-
  • HCO₃^-
  • Bladder bile
• N. vagus
  
  • Parasympathetic
• Secretin
  
  • Buffer
• CCK (cholecystokinin)
  
  • Gall bladder
  • Sphincter
  • Gall release
  • Emulsifyes
• Bile salts
  
  • Cholesterol

Question 5

Topics to include in the essay

Answer 5

1. Bile production
   
   • Storage of bile
   • Components of bile
   • Bile acids
2. Functions of the bile
   
   • Enterohepatic circulation
3. Regulation of bile secretion

Question 6

Bile production

Storage and emptying

Answer 6

• Bile is stored in the gall-bladder
• It can be condensed by reabsorbing NaCl, water and NaHCO₃^-
• Produced continuosly
  
  • Car: Bile emptying is periodical due to food-intake just 1-2 times a day
  • Eq: constantly evacuated to the duodenum (due to ø gall bladder)

Question 7

Bile production

Which cells produces bile?

Answer 7

• Parenchyma cells of the liver
  
  • Secrete:
    
    • Bile salts
    • Cholesterol
    • Phospholipids
    • Bile pigment
• Epithelial cells of the bile canaliculi
  
  • Responsible for the electrolyte content of the bile (Na⁺, K⁺, Cl^-, HCO₃^-)

Question 8

Bile production

Components of bile

Answer 8

• Bile salts
  
  • ​Conjugated bile acids form salts = bile salts
• Cholesterol​
• Lechitin
  
  • ​Amphiphatic (hydrophilic + hydrophobic)
• Bile pigment
• Electrolytes (HCO₃^-)
• Bile salts, cholesterol and lechitin form micelles

Question 9

Bile production

Bile acids

Answer 9

• Bile acids are synthesized from cholesterol, and forms up to 50% of the dry mass of bile
• Primary bile acids:
  
  • Cholic acids
  • Chenodeoxycholic acid
• Secondary bile acids:
  
  • Deoxycholic acid (from cholic acid)
  • Litocholic acid (from chenodeoxycholic acid)
• Primary bile acids can be conjugated with taurine and glycine in the liver cells
  
  • Glycocholic acid
  • Taurocholic acid
• Primary bile acids are dehydroxylated and deconjugated by bacteria in the terminal end of ileum, and secondary bile acids are generated → enters the enterohepatic circulation

Question 10

Functions of bile

Role of bile

Answer 10

• Bile salts take part in emulsifying fat (secretory)
• Metabolic end-products and antibodies (excretory)

Question 11

Functions of bile

Enterohepatic circulation

Answer 11

• 95-98% of bile salts are absorbed in the ileum
  
  • Gets into the liver via the v. Porta
  • Hepatocytes take them up → conjugate them again, or hydrolyses the secondary bile acids and secrete them into the bile
• A smaller portion (5%) is absorbed passively from the jejunum
• Bile salt transported to the liver by the enterohepatic circulation inhibit the bile acid synthesis from cholesterol → repression mechanism

Question 12

Regulation of bile secretion

Answer 12

• Gall bladder (ø eq)
  
  • Liver-bile is stored and concentraded (due to absorption of Na⁺, Cl^- and HCO₃^-)
  • Result: bladder-bile (with concentrated bile components)
• N. vagus
  
  • Parasympathetic effect of n. vagus → gall bladder cotract
• Secretin
  
  • Stimulates secretion of bile to the intestine
  • Main role: buffering the acetic intestinal content
• CCK (cholecystokinin)
  
  • High lipid content of chime stimulates CCK production → gall bladder contract and sphicter relax → increased gall release
• Bile salts
  
  • Inhibit synthesis of bile acids from cholesterol

Question 13

Interspecies production of bile

1. Highest production
2. Lowest production

Answer 13

• Highest: horse (5-6 l/day)
• Lowest:
  
  1. Chicken
  2. Cat