Question

The assimilation of fats includes
(1) micelle formation
(2) secretion of chylomicrons
(3) emulsification of fat
(4) absorption of fat by enterocytes
Which sequence best describes the correct temporal order of these events?

• A. 3, 4, 1, 2
• B. 3, 1, 4, 2
• C. 3, 1, 2, 4
• D. 3, 2, 4, 1

Answer 1

The correct option is B 3, 1, 4, 2

Fat entering the small intestine is first emulsified into smaller globules by bile released from the gallbladder.
Pancreatic lipase in conjunction with the co-enzyme lipase then digests the fat (which is mostly triglycerides) into monoglycerides and free fatty acids; these substances then become surrounded by bile salts to form water-soluble aggregates called micelles.
When a micelle makes contact with an enterocyte of the intestinal wall, the monoglycerides and free fatty acids diffuse directly through the cell membrane into the enterocyte; triglycerides are too large to be absorbed.
Inside the enterocyte, the monoglycerides and free fatty acids form new triglyceride molecules that are subsequently packaged by the Golgi apparatus into chylomicrons. The chylomicrons exocytose at the basolateral membrane of the enterocyte and enter a lymphatic capillary (central lacteal) in the villus.