Master in Sexology and Psychosexual Counseling. For More Info WhastApp- 9604715783/9359863878. Parasympathetic Nervous system is responsible for the erection in males and for lubrication in females. The parasympathetic fibers originate in the 2nd, 3nd, 4th sacral segments of spinal cord to form a single nerve on each side. Stimulation of these nerves (NERVI Erigentes) leads to dilation of arterioles filling up the penis with blood, producing erection of the penis. The veins have valves which prevent the blood from leaving penis.