The TCA cycle oxidatively decarboxylated pyruvate to carbon dioxide reduced coenzymes and ATP.
Reduced coenzymes may then be used to generate ATP via oxidative phosphorylation in the electron transfer chain.
The TCA cycle also acts as a metabolic hub - many metabolic pathways lead in and out of the cycle so that many compounds may be inter converted via this route. The liver is particularly important as a site at which many nutrients may be converted from one to another.
The TCA cycle can supply many metabolic intermediates.