<P> If the first and third chain R and R" are different, then the central carbon atom is a chiral centre, and as a result the triglyceride is chiral . </P> <P> The pancreatic lipase acts at the ester bond, hydrolyzing the bond and "releasing" the fatty acid . In triglyceride form, lipids cannot be absorbed by the duodenum . Fatty acids, monoglycerides (one glycerol, one fatty acid), and some diglycerides are absorbed by the duodenum, once the triglycerides have been broken down . </P> <P> In the intestine, following the secretion of lipases and bile, triglycerides are split into monoacylglycerol and free fatty acids in a process called lipolysis . They are subsequently moved to absorptive enterocyte cells lining the intestines . The triglycerides are rebuilt in the enterocytes from their fragments and packaged together with cholesterol and proteins to form chylomicrons . These are excreted from the cells and collected by the lymph system and transported to the large vessels near the heart before being mixed into the blood . Various tissues can capture the chylomicrons, releasing the triglycerides to be used as a source of energy . Liver cells can synthesize and store triglycerides . When the body requires fatty acids as an energy source, the hormone glucagon signals the breakdown of the triglycerides by hormone - sensitive lipase to release free fatty acids . As the brain cannot utilize fatty acids as an energy source (unless converted to a ketone), the glycerol component of triglycerides can be converted into glucose, via gluconeogenesis by conversion into dihydroxyacetone phosphate and then into glyceraldehyde 3 - phosphate, for brain fuel when it is broken down . Fat cells may also be broken down for that reason if the brain's needs ever outweigh the body's . </P> <P> Triglycerides cannot pass through cell membranes freely . Special enzymes on the walls of blood vessels called lipoprotein lipases must break down triglycerides into free fatty acids and glycerol . Fatty acids can then be taken up by cells via the fatty acid transporter (FAT). </P>

Cells that have the ability to store triglycerides are