Stages of physiological arousal during sexual stimulation[ edit ] This Indian Kama sutra illustration, which shows a woman on top of a man, depicts the male erection, which is one of the physiological responses to sexual arousal for men. Sexual activity can be consensual, which means that both or all participants agree to take part and are of the age that they can consent, or it may take place under force or duress, which is often called sexual assault or rape. This figure rises with each grade. People may not be able to detect that their sexual partner has one or more STIs, for example if they are asymptomatic show no symptoms. Teenagers who had their first sexual experience at age 16 revealed a higher well-being than those who were sexually inexperienced or who were first sexually active at a later age of The object of desire can often be shoes, boots, lingerie, clothing, leather or rubber items. The potential for injury or even death that exists while engaging in the partnered versions of these fetishes choking and bondage , respectively becomes drastically increased in the autoerotic case due to the isolation and lack of assistance in the event of a problem. A man's urinary bladder closes to prevent urine from mixing with semen. A person may engage in sexual activity for purely monetary considerations, or to obtain some advantage from either the partner or the activity. In a rural upstate New York community, a cross-sectional study of teenagers was completed in and Sexuality in older age Typically, older men and women maintaining interest in sexual interest and activity could be therapeutic; it is a way of expressing their love and care for one another. National sex surveys given in Finland in the s revealed aging men had a higher incidence of sexual intercourse compared to aging women and that women were more likely to report a lack of sexual desire compared to men. A higher percent of African American and Hispanic adolescents are sexually active than White adolescents. Sexually active life expectancy The frequency of sexual activity might range from zero sexual abstinence to 15 or 20 times a week.