When we use the past tense in sentences we refer to past actions that have not yet defined their end, we must take into account the person, gender, number and time indicated in a sentence to conjugate the verb correctly and have coherence with what you want to express yourself.
Las hormonas alteran la actividad celular al estimular o inhibir las características de los procesos celulares de sus celdas objetivo. El estímulo hormonal produce uno o más de los siguientes cambios: