The term sexual cycle refers to the reproductive cycle. In human females, the sexual cycle, which begins at puberty and ends with menopause, is based on the cyclic development and release of the ovum (egg) by the ovaries. Each cycle lasts approximately 28 days and has two phases--the follicular phase, which begins with the first day of the menstrual cycle (menses is Latin for month) and continues until ovulation; and the luteal phase, which follows ovulation. Sexual--or reproductive--cycles are regulated by sex hormones, the release of which is controlled by the hypothalamus and pituitary gland. Although stress and illness can sometimes disrupt the cycle, the only normal interruption of a woman's sexual cycle is pregnancy.

During the follicular phase, luteinizing hormones (LH) and follicle stimulating hormones (FSH) released by the pituitary gland encourage follicles--an envelope of special cells encasing each individual oocyte housed in the ovaries--to secrete...