Which hormone is responsible for the process of ovulation?

Appeared in: Bihar CHO -2019

Explanation

Luteinizing Hormone (LH) is the hormone directly responsible for triggering ovulation.
About two days before ovulation, the secretion of LH from the anterior pituitary gland increases dramatically, creating what is known as the 'LH surge'.
This surge causes the final maturation of the ovarian follicle, leading to its rupture and the release of the ovum (egg).
Without this preovulatory surge of LH, ovulation will not occur, even if FSH levels are high.

Option A: FSH's primary role is to stimulate the growth and development of ovarian follicles during the follicular phase (the first half of the menstrual cycle). It does not directly trigger the release of the egg.
Option C: ACTH (Adrenocorticotropic Hormone) is involved in the body's stress response. It stimulates the adrenal glands to produce cortisol and is not involved in the regulation of the menstrual cycle or ovulation.
Option D: This option is incorrect because ACTH has no role in ovulation. While both FSH and LH are crucial for the overall process, only LH is the direct trigger.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of the female reproductive cycle as background academic context rather than a clinical decision trigger.
Ovulation predictor kits (OPKs) sold over-the-counter work by detecting the LH surge in urine, helping individuals identify their most fertile window.
In fertility treatments, a medication called human chorionic gonadotropin (hCG) is often used as a 'trigger shot'. hCG is structurally similar to LH and binds to the same receptors, effectively mimicking the natural LH surge to induce ovulation.
What if a patient has Polycystic Ovary Syndrome (PCOS)? In many cases of PCOS, there is a persistently high level of LH relative to FSH. This hormonal imbalance prevents the development of a dominant follicle and the characteristic LH surge, leading to anovulation (lack of ovulation) and infertility.

How to Approach the Question

First, identify the core physiological process asked in the question, which is 'ovulation'.
Next, recall the key hormones involved in the female reproductive cycle: GnRH, FSH, LH, estrogen, and progesterone.
Differentiate the specific primary function of each hormone. Remember that FSH is for 'Follicle' growth and LH is for 'Luteinizing' or triggering ovulation.
Consider the other options. ACTH is related to the adrenal gland and stress, so it can be eliminated as irrelevant to the reproductive cycle.
Based on this differentiation, conclude that the LH surge is the specific event that triggers ovulation.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 35-37

E6 Medicine Harrison 22e Part 2 p. 895-897

E6 Pharmacology Katzung 16e p. 1049-1051

Practise the full Bihar CHO -2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.