Figure 2.

Ketogenesis. Fatty acids undergo the process of β-oxidation in the liver, resulting in the formation of ketone bodies. These are then transported to the blood vessels and then to the neurons where, after conversion to acetyl-CoA, they enter the TCA cycle. The alternative energy source compensates for the smaller contribution of glucose to the ATP yield. (HMG-CoA: 3-hydroxy-3-methyl glutaryl-CoA; HMG-CoA synthetase: 3-hydroxy-3-methyl glutaryl-CoA synthetase; HMG-CoA lyase: 3-hydroxy-3-methyl glutaryl-CoA lyase; ACA: acetoacetate; D-βHB: D-β-hydroxybutyrate; TCA: tricarboxylic acid cycle).