Absorción, digestión y transporte de lípidos

Digestion, Absorption, and Transport of Lipids

In this video, we will discuss the digestion, absorption, and transport of lipids.

Digestion of Lipids

• Lipid digestion begins with the action of lingual and gastric lipases.

• These enzymes hydrolyze triglycerides into free fatty acids and monoglycerides.

• In the duodenum, most lipid digestion occurs through the release of bile salts.

• Cholecystokinin (CCK), a hormone released by duodenal cells, stimulates gallbladder contraction and pancreatic enzyme secretion.

Modification of Lipids in the Duodenum

• Bile salts modify lipids by forming micelles.

• Micelles make lipids more accessible to pancreatic lipase for further digestion.

• Pancreatic lipase hydrolyzes triglycerides into fatty acids, monoglycerides, and glycerol.

• These products diffuse into the intestinal epithelial cells.

Absorption and Transport of Lipid Products

• Inside intestinal epithelial cells, lipid products are reassembled into triglycerides in the smooth endoplasmic reticulum.

• Triglycerides are then packaged into chylomicrons coated with apolipoprotein B48.

• Chylomicrons leave the endoplasmic reticulum and are secreted via Golgi complex to reach the lymphatic vessels.

Transport of Chylomicrons

• Newly formed chylomicrons acquire additional apolipoproteins from high-density lipoproteins (HDL).

• Chylomicrons circulate in blood vessels where they encounter lipoprotein lipase (LPL).

• LPL hydrolyzes triglycerides within chylomicrons, releasing fatty acids and glycerol for storage in adipose tissue.

• Remnants of chylomicrons transfer phospholipids and apolipoproteins to HDL through cholesterol ester transfer protein (CETP).

• The remaining chylomicron remnants are transported to the liver for degradation.

Plasma Lipoproteins

• Very-low-density lipoprotein (VLDL) is synthesized in the liver and transports triglycerides to adipose tissue and muscle.

• Low-density lipoprotein (LDL) serves as a source of cholesterol for various cells.

• High-density lipoprotein (HDL) is synthesized in the liver and small intestine, and it transports cholesterol from peripheral tissues back to the liver.

Reverse Cholesterol Transport

• HDL acquires cholesterol from peripheral tissues and transports it back to the liver.

• In the liver, endogenous cholesterol along with VLDL remnants are used to synthesize LDL particles.

Conclusion

• Lipids undergo digestion, absorption, and transport processes in the body.

• Bile salts aid in lipid modification, while pancreatic enzymes facilitate lipid digestion.

• Chylomicrons transport dietary lipids, while plasma lipoproteins play a role in lipid distribution throughout the body.