The ovarian cycle is initiated by?

AIIMS Patna NO - 2020

Obstetrics & Gynaecology

Easy

Appeared in: AIIMS Patna NO - 2020

Explanation

The ovarian cycle begins with the follicular phase, which is initiated by a rise in Follicle-Stimulating Hormone (FSH) from the anterior pituitary gland.
FSH stimulates the recruitment and growth of a cohort of immature ovarian follicles.
As the follicles grow under the influence of FSH, they begin to produce oestrogen, but FSH is the initial trigger for this process.
This initial stimulation by FSH is essential for selecting a dominant follicle that will eventually mature and be released during ovulation.

Option A: Progesterone levels are very low at the beginning of the ovarian cycle. Its primary role is in the second half (luteal phase) after ovulation, where it prepares the endometrium for implantation.
Option C: Endorphins are neurotransmitters associated with the body's response to pain and stress. They do not have a primary role in initiating or regulating the hormonal sequence of the ovarian cycle.
Option D: Oestrogen levels are low at the start of the cycle. Oestrogen production increases as a result of follicular growth stimulated by FSH. While crucial for the cycle, it is not the initiator.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of the ovarian cycle as background academic context rather than a clinical decision trigger.
Understanding that FSH initiates the ovarian cycle is fundamental for nurses in fertility counseling. Many fertility treatments involve administering FSH to stimulate follicle development.
Patient education regarding menstrual irregularities often involves explaining the roles of different hormones. A nurse can clarify that issues with FSH secretion can lead to anovulatory cycles or amenorrhea.
What if? If a patient has consistently low FSH levels, the nurse would anticipate that the patient would experience infertility and lack of menstrual cycles (amenorrhea), as follicular development would not be initiated.

How to Approach the Question

First, identify the core of the question: it asks for the hormone that starts or initiates the ovarian cycle.
Recall the sequence of the menstrual cycle, which is divided into the follicular phase and the luteal phase.
Remember that the beginning of the cycle involves the growth of follicles in the ovary.
Consider the function of each hormone listed in the options. FSH stands for Follicle-Stimulating Hormone, and its name directly implies its function.
Eliminate the other options based on their primary roles: Oestrogen rises after follicles start growing, Progesterone is dominant after ovulation, and Endorphins are not part of the primary hormonal axis for reproduction.
Conclude that FSH is the hormone responsible for initiating follicular growth and therefore the ovarian cycle.

Concept Tested & Keywords

Q7qrw5Gt2oHXcbC3N-y6GB

E6 Pharmacology Katzung 16e p. 1122-1124

E6 Medicine Harrison 22e Part 2 p. 1033-1035

E6 Physiology Essentials Sembulingam 10e Part 2 p. 129-131