The citric acid cycle (Krebs cycle) metabolizes AcetylCoA mainly obtained from pyruvic acid by glycolysis.
1 Citrate 2 Isocitrate 3 α -Cetoglutarate 4 Succinyl CoA 5 Succinate 6 Fumarate 7 Malate 8 Oxaloacetate
For glycolysis see → here For the passage from pyruvate to acetylCoA see → here For details on the role of NAD+ see → here For details on the role of the FAD see → here