Biliary Tract Obstruction

Synthesis: Bile salts are steroid molecules synthesized by hepatocytes.
Primary Bile Salts:
- Cholic acid and chenodeoxycholic acid are the primary bile salts in humans.
- These account for approximately 80% of the bile salts produced.
Conjugation:
- Primary bile salts are conjugated with either taurine or glycine.
Secondary Bile Salts:
- In the intestine, primary bile salts can undergo bacterial alteration to form secondary bile salts:
  - Deoxycholate
  - Lithocholate
Function:
- The primary purpose of bile salts is to solubilize lipids and facilitate their absorption in the intestine.

Origin: Bile acids are synthesized from cholesterol.
Pathways:
- Classic Pathway:
  - Leads to the formation of cholic acid.
  - This is the predominant pathway of bile acid synthesis in humans.
- Alternative Pathway:
  - Results in the synthesis of chenodeoxycholic acid.
Bile Acid Pool:
- 60% to 70% of the bile acid pool consists of cholic acid and its metabolite deoxycholic acid.
- Chenodeoxycholic acid is less commonly found in human bile compared to cholic acid.

(Source: Blumgart, 6th edition, page 124)

Question: Which of the following lesions is not commonly associated with Type I biliary tract obstruction?

Options: a) Choledocholithiasis

b) Carcinoma of gallbladder

c) Cholangiocarcinoma

d) Common bile duct ligation

Answer: a) Choledocholithiasis

Explanation:

Type I Biliary Tract Obstruction is typically caused by conditions leading to complete obstruction of the bile duct. Common lesions include:
- Carcinoma of the gallbladder (Option B)
- Cholangiocarcinoma (Option C)
- Common bile duct ligation (Option D)
Choledocholithiasis (Option A), which refers to the presence of stones in the common bile duct, is more commonly associated with Type II: Intermittent Obstruction, rather than complete obstruction.

Correct Answer: A) Choledocholithiasis

Question: Which of the following is not a pathophysiological alteration associated with obstructive jaundice?

Options: a) Decrease synthesis of albumin and clotting factors

b) Decrease capacity to excrete drugs through bile

c) Increase Kupffer function clearance

d) Decrease renal function

Answer: c) Increase Kupffer function clearance

Explanation:

Option A (Decrease synthesis of albumin and clotting factors): Obstructive jaundice leads to a decrease in the synthetic function of hepatocytes, including the production of albumin and clotting factors.
Option B (Decrease capacity to excrete drugs through bile): In obstructive jaundice, there is a reduced capacity to excrete drugs that are normally secreted into bile, such as antibiotics.
Option C (Increase Kupffer function clearance): This statement is not true. Obstructive jaundice actually decreases the function of Kupffer cells, reducing their ability to clear bacteria and endotoxins, and impairing immune function.
Option D (Decrease renal function): Renal function can be compromised in obstructive jaundice due to factors like hypovolemia, bile salt effects, and endotoxemia.

Correct Answer: C) Increase Kupffer function clearance

These changes weaken immune defense, increasing susceptibility to infections.

(Source: Blumgart, 6th edition, page 129)