Answer to Question 1
Although some fatty acids are cleaved from the glycerol backbones in the mouth and stomach by lingual and gastric lipases, respectively, fatty acids need to be chemically cleaved from those still attached to glycerol. To accomplish this, lipid-containing chyme stimulates cells in the small intestine to release the hormone secretin, which in turn stimulates the pancreas to release pancreatic juice containing the enzyme pancreatic lipase. Secretin, a hormone made by enterocytes lining the small intestine, also signals the release of sodium bicarbonate and proteases from the pancreas. Pancreatic lipase completes triglyceride digestion by cleaving the remaining fatty acids from their glycerol molecules. In general, two of the three fatty acids are removed from the triglyceride molecules, producing a monoglyceride and two free (unbound) fatty acids. The final products of lipid digestion (fatty acids, glycerol, and monoglycerides) are then taken up into the intestinal cells and circulated to the rest of the body. This process requires special handling because many of these substances are hydrophobic, while both the interiors of the intestinal cells and the circulatory system are hydrophilic. Once again, it is the amphipathic property of phospholipids that makes absorption possible.
Answer to Question 2
D
Atherosclerosis. (a) A sectioned coronary artery that exhibits an accumulation of fatty plaque, whic
the fatty acid molecules expose the smallest possible hydrophobic surface area
Structures of the ionized forms of some representative fatty acids (part 2)
The activation of pancreatic zymogens
Regulation of fatty acid synthesis in animal cells
Pancreatic Islets