Italian term (edited): vive attraverso un’attività fisiologica ed biochimica

Alternative: Hair is sustained through physiological and biochemical activity.
Alternative 2: Hair lives through physiological and biochemical processes.
(These are ways which a specialist might express the author's thought.)
Note 1: In general, you might not elect to say "hair lives" because only part of the hair is alive, namely the intradermal hair follicle. Most of the hair, though perhaps not the part most relevant to the author's discussion, is dead.
Note 2: "factors" is not bad, but it is not a translation of the author's thought, rather it is a gloss over that thought. I particularly do not like "factors" because it over-generalizes the author's quite specific statement. We as translators should not re-write an author without a good reason.