Final answer:
When sexual desire builds as a person engages in sexual activity, it is referred to as the sexual response cycle, which includes the excitement phase followed by the plateau phase, leading up to orgasm.
Step-by-step explanation:
The term for the building of sexual desire when a person engages in sexual activity is known as the sexual response cycle. This cycle is typically divided into four phases: excitement, plateau, orgasm, and resolution. During the excitement phase, there is a significant increase in sexual arousal marked by physiological changes like erection and lubrication. As arousal continues and intensifies during the plateau phase, this is often where the buildup of sexual tension occurs, leading to the next phase.
Both the excitement and plateau phases are integral in increasing sexual desire and are a normal part of the sexual response during intercourse. These stages result in various physiological changes that prepare the body for potential orgasm. Understanding this cycle can provide insight into the dynamics of sexual activity and individual sexual health.