By which route do chylomicrons reach the bloodstream after leaving an intestinal epithelial cell?
ABlood capillaries, then the hepatic portal vein
BBile canaliculi, then the common bile duct
CLacteals, then the thoracic duct and a vein
DIntestinal glands, then the hepatic artery
Answer & Solution
Correct answer: C. Lacteals, then the thoracic duct and a vein
1. Free fatty acids and monoacylglycerides entering the epithelial cell are rebuilt into triglycerides.
2. Those triglycerides are wrapped with phospholipids, cholesterol and a protein coat to form a chylomicron.
3. A chylomicron is too big to cross the basement membrane of a blood capillary.
4. It enters the large pores of a lacteal instead, and the lacteals join to form lymphatic vessels.
5. The lymphatic vessels empty through the thoracic duct into the subclavian vein.
6. The hepatic portal route is the one taken by sugars, amino acids and short-chain fatty acids.
7. Bile canaliculi carry bile away from hepatocytes and never carry absorbed nutrients.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 23 "The Digestive System", section 23.7 Chemical Digestion and Absorption: A Closer Look_
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