102 7.33 Brain Macronutrient Metabolism (91/105) -- Nutrition

102 7.33 Brain Macronutrient Metabolism Fatty acid breakdown does not occur to any great extent in the brain because of the low activity of an enzyme in the beta-oxidation pathway limits the pathway’s activity1. Compared to the extrahepatic tissues as a whole, in the brain the following pathways are not performed or are not important: Glycogen synthesis and breakdown Lactate synthesis Fatty acid synthesis and breakdown Triglyceride synthesis and breakdown Protein synthesis and breakdown These pathways are crossed out on the figure below. Fatty acid breakdown does not occur to any great extent in the brain because low activity of an enzyme in the beta-oxidation pathway limits the activity of this pathway2. By removing those pathways the only pathways left are: Glycolysis Ketone body breakdown Thus, due to its limited metabolic capabilities, the brain needs to receive either glucose or ketone bodies to use as an energy source. References & Links 1. J BIol Chem 262 (27): 13027-13032. 2. http://en.wikipedia.org/wiki/File:CellRespiration.svg