Do females need to orgasm?

Ok, so somewhat of a left-field question as a result of a discussion between my g.f and I.

We were discussing masturbation and why people masturbate. I have read that for men there is a natural desire to release seamen out of the body regularly, obviously this is not the case for women.

So as a women, if you don't masturbate for a period of time (say a week for arguements sake), do you feel the need to have an orgasm - like is there that built up pressure down there that makes you want to masturbate for a release?

Sorry for such a strange question