What does time and dose -dependent and habituation mean?

Time and dose -dependent is aka dose–response relationship, or exposure–response relationship. It describes the biochemical change in activity of an enzyme caused by differing levels of exposures (or doses) to a system after a defined exposure time. This relationship in rarely linear. A dose or exposure might up-regulate in a short time frame, but over time the overall activity eventually deceases. This phenomenon can be influenced by habituation/desensitization in the case of neurotransmitters or some medications. It is also related to hormesis, which is the process of a beneficial effect from exposure to low doses of an agent that, in larger doses, is otherwise toxic or lethal when given at higher doses.