This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Positive feedback action of estrogen for inducing luteininzing hormone surge is associated with which of the following steroid hormone ratios in peripheral circulation: \nSelect and explain. \nA. High estrogen : low progesterone, B. Low esterogen : high progesterone, C. Low esterogen : low progesterone, D. High esterogen : high progesterone', 'role': 'user'}, {'content': "Answer: A \nExplanation: A i.e. High estrogen, low progesteroneL H surge causes ovulationQ. For ovulation to occur the hormone picture should be high estrogen & low progesteronQEstrogenAt the time of ovulation, ova in the Graffian follicle needs to be well developed, which is accomplished by ' high estrogenQLH secretion is held in check by negative feedback effect of rising plasma estrogen.At 36-48 hours before ovulation estrogen feed back effect becomes positive & initiates a burst of LH secretion (LH surge)QProgesteronProgesteron is secreted by the corpus luteum, which is the remnant of graffian follicles after the ova has been released. Thus progesterone would rise only after ovulationQ.Large doses of progesterone inhibit LH secretion & potentiate the inhibitory effect of estrogen, preventing ovulation", 'role': 'assistant'}]