Give reasons why lipid molecules are absorbed into the lacteals and not directly into capillaries of villi. ?

Question

Give reasons why lipid molecules are absorbed into the lacteals and not directly into capillaries of villi. ?

Answer 1

Because fatty acids and 2-monoglycerides are soluble in the lipid component of the intestinal membranes, they can diffuse directly into the epithelium without need of carrier molecules. Once inside, the free fatty acids are again complexed to the 2-monoglycerides to reform triglycerides. This occurs in the endoplasmic reticulum and the newly formed triglycerides are invested with a membrane to form a droplet called a chylomicron.

Chylomicrons are released into the lamina propria by exocytosis. Since all other digested products pass to blood vascular capillaries and then to the hepatic portal vein, one might suppose the same to be true for chylomicrons. Such is not the case because the large size of chylomicrons prevents entry through the simple squamous epithelial lining of blood vascular capillaries. Instead, chylomicrons pass into lacteals that are lymphatic capillaries with fenestrated membranes, i.e., membranes with gaps large enough to accommodate the entry of chylomicrons. Chylomicrons pass through the lymphatic system before being dumped into the blood vascular system through the right lymphatic and thoracic ducts.