Reproductive System and Hormonal Control (3B) Practice Test

In a study of pulsatile gonadotropin regulation, healthy adult volunteers received a continuous (nonpulsatile) intravenous infusion of gonadotropin-releasing hormone (GnRH) for 72 hours. Serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured before infusion and at 72 hours. Participants reported no change in sleep or caloric intake during the protocol. The investigators propose that the observed gonadotropin pattern reflects a specific principle of hormonal regulation in the hypothalamic–pituitary–gonadal axis.

Which outcome is most consistent with hormonal feedback and signaling dynamics under these conditions?

A reproductive physiology lab monitors hormone profiles in participants across a single menstrual cycle. In a subset, estradiol rises to a sustained high level for ~48 hours, followed by a sharp rise in LH and subsequent ovulation. The investigators emphasize that the direction of feedback depends on the magnitude and duration of steroid signaling.

Which statement best describes the hormonal regulation illustrated?