Humans have no anaerobic respiration. The terminal electron acceptor in respiration is always oxygen, which is reduced at complex IV in the respiratory chain. Alternative electron acceptors are mostly found in bacteria and archaea.
Anaerobic metabolism of glucose to lactate in humans is a fermentation process. It consists of glycolysis, which converts glucose to pyruvate, which in turn is converted to lactate by lactate dehydrogenase. There is no terminal electron acceptor in this case; instead, energy is extracted from glucose by rearranging the molecular structure of the sugar into a more favorable ("low energy") configuration, without any net donation of electrons.