Sexual response cycle There are two physical changes the body must under go if a women is to experience orgasm. The first is "vascongestion," the pooling of blood in the breasts and genitals. The second is "Myotonia" or "neuromuscular tension," the build up of energy in the nerve endings and muscles of the entire body. The physiologic mechanism of clitoral stimulation involves the release of nitric oxide (NO) in the female genital tissue during sexual activity. (NO) then activates the enzyme guantylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP) producing smooth muscle relaxation, and allowing increase of blood flow. Timothy J. Maher. Ph. D. regarding L-Arginine, continuing education module. New Hope Institute.