Glucose is broken down into acetate attached to cofactor A, called acetyl-CoA. It may or may not cycle through the TCA system.
TCA means tri-carboxylic acid. Specifically, it's citric acid. So the TCA cycle is sometimes called the citric acid cycle.
The molecule NADH carries energy to the respiratory system, where it energizes three ATP molecules. If respiration is not possible, it must dump its high energy electron elsewhere, called fermentation. The definition of fermentation is "a final electron acceptor other than oxygen".
