The orgasm

There are four phases to an orgasm according to Masters and Johnson they are:

Excitement
Men experience testies increase in size and elevate, erection
Women experience lubrication, erection of clitoris, breast increase in size and elevate
Both experience myotonia, increased heart rate and blood pressure

Plateau - this phase precedes the orgasmic phase
Men experience testies elevate into position for ejaculation and the coupers gland secretes a few drops of fluid prior to ejaculation, this fluid can be fertile.
Women experience uterus increases and elevates, vaginal barrel contracts, clitoris withdraws

Orgasmic
Men have you stages in this phase -
Stage 1. contractions gather together semantic fluid to urethral bulb at the base of the penis
Stage 2. Relax sphincter and the man has now reached a period of inevitability
Women experience 3 to 15 contractions leading to the release of deep muscular tension
Both experience body spasms, increase of heart rate and breathing

Resolution
Men experience two stages in this phase as well
Stage 1. After one minute of orgasm there is a return of blood.
Stage 2. Return of the rest of the blood this stage takes several minutes
Women experience a return of all their blood
Both experience myotonia releasing

For men there is still a refractory period that the length of depends on the age and health of the man