Digestion

Digestion was the process of breaking down food after consumption. As Liz Shaw explained: "Your stomach works to break down the food you eat and extract the goodness from it. The waste is passed into the small intestine." Sometimes in this process, excess acid could be formed and lead to indigestion, which may also result in hiccups. (PROSE: Hiccup in Time)

Historians who had been allowed access to the "Monster Vaults" of the databanks in the Doctor's TARDIS observed that the heads of the Abzorbaloffs' absorbed victims remained alive and conscious within the Abzorbaloff's digestive tract and only when it had completely drained their brains were the heads fully assimilated into its "fleshy corpulence". (PROSE: The Monster Vault)