People
                interpret  their sexual responses in various ways. Body-response to sexual arousal are identical  whether the
                stimulation comes from  touching, kissing, intercourse,
                masturbation, fantasy, watching a movie, or reading a book. This
                statement does than dancing or playing the violin is "
                only" mechanical because certain parts of the body are
                involved in these activities. Human sexual response is
                multidimensional, with input from feelings and thoughts,
                learning and language, personal and cultural values, and many
                other sources combining  with our biological reflexes to
                create a total experience. 
                To
                understand the complexities of human sexuality, it is helpful to become familiar with the details of sexual physiology
                functions of our sexual anatomy. Learning about the various
                responses of the body during sexual arousals and about  the
                forces that regulate them will increase your awareness of your
                own and your partner's responses and may clarify many 
                misconceptions, myths, and questions about sex. It is also
                important to understand sexual physiology to comprehend many
                sexual disorders. 
                Sources
                Of Sexual Arousal
                When
                people talk about sexual arousal, they frequently say 
                they are " turned on, " revved up" or hot".
                Each phrase likens sexual arousal to an energy system, and as a starting
                point, this comparison is useful. From a scientific perspective,
                sexual  arousal can be defined as a state of activation of
                a complex system of reflexes involving the sex organs and the
                nervous system. The brain itself, the  controlling part of the
                nervous system, operates with electrical and chemical impulses
                wired" to the rest of the body through the spinal cord and
                peripheral nerves. Signals from other parts of the body (like
                the skin, genitals , breasts) are integrated and focused in the
                brain, for  without sexual thoughts, feelings , or images
                sexual response is fragmentary and incomplete. At times, sexual
                arousal  may be largely a cerebral event that is, a
                person may be aroused while no  visible physical changes
                are  occurring elsewhere in the  body. On other 
                occasions genital sensations can be so intense that they block
                out  awareness of almost everything else.
                Sexual
                arousal can occur under a wide variety of circumstances. It may
                be the  result of voluntary actions such as kissing, hugging
                , reading  a sexy book , or going  to an erotic movie.
                Sexual arousal can also be unexpected, unwanted, or event
                alarming. Consider, for instance, the following situations: 
                1. 
                A twelve-year-old  boy gets an erection while taking a shower
                in a crowded all-male locker room at school; 
                2. 
                A female college
                student who is an ardent feminist become sexually aroused while
                watching  a rape scene in a movie; 
                3. 
                A female medical
                student is sexually excited when she examines an elderly male
                patient; 
                4. 
                A male lawyer is sexually aroused by discussions
                with a female client who hires him to help her obtain a divorce.
                These people may be embarrassed or uncomfortable temporarily,
                but unexpected sexual arousal is normal and happens to most of
                us  occasionally. 
                The
                sources of sexual  arousal are also varied. The process of
                getting " turned on"  may be triggered by direct
                physical contact such as a  touch or a kiss, or may be
                activated by a verbal invitation (" let's make love")
                a nonverbal message (" body language"), or a visual
                cue (such as nudity or a particular clothing style). It may also
                spring from fantasies or the most everyday occurrences clothing
                rubbing against the genitals, the  rhythm of a moving
                vehicle, or taking a bath or shower. 
                 Sexual arousal occurs in
                all age groups from infants to the elderly, and it occurs when
                we are asleep as well as when we are awake. Men have about a
                half dozen erections during a night's sleep (the erections
                usually last five to ten minutes), and women have similar
                episodes of vaginal lubrication during sleep. These reflex
                responses our automatically and are not controlled by the specific
                content of dreams. 
                *****
                Evaluating
                Contraceptive Effectiveness
                and Safety