Famed sex researchers William H. Masters and Virgižnia E. Johnson were the first to identify the human sexual response cycle. The cycle consists of four phases: excitement, plateau, orgasm, and resolution. But full sexual response is not limited to intercourse, as there are many similar things that happen to your body during oral sex, masturbation, and fantasy as what occurs during vaginal intercourse.
Oral sex, especially, is an important part of many relationships. Oral can range from an act of foreplay to the main event. Couples whose sexual relationship is exclusively oral will tell you that they most definitely experience the four phases of sexual response as well as all of the body changes related to sexually stimulating activities.
It's important to recognize the way your body responds and changes to sexual arousal. The experts at the University of California, Santa Barbara agree that knowledge and understanding of the changes that your body undergoes during a sexual encounter can help "enhance your sexual experiences, deepen your relationship with a partner, or resolve the origins of a sexual problem."
You may have been too distracted to notice the ways in which your body physically responds to receiving oral sex, but if keep your eyes and senses alert next time, you may just notice some of these things happening to you.