1. penile erection produced by stimulation of the male genitalia.

2. vaginal secretion and lubrication and swelling of the clitoris produced by stimulation of the female genitalia.

3. the reflex activity involved in orgasm.

4. components of sexual behavior, such as the cremasteric reflex, that are not under direct control of the higher brain levels and may be stimulated through spinal or bulbar neural connections.