In a way, you could view T3 as being the “fuel” that fires the metabolism, whereas thyroxine (T4) is merely the “pump” that delivers said fuel effectively into the system.
An enger Manéier kënnt Dir T3 als "Brennstoff" gesinn, dat den Metabolismus brong ass, während Thyroxin (T4) just d'"Pomp" ass, déi de Brennstoff effektiv an d'System liefert.