The ovarian cycle is initiated by:
A. progesterone
B. estrogen
C. endorophins
D. follicle stimulating hormone
Correct Answer: D. follicle stimulating hormone
Explanation
The ovarian cycle is initiated by the hypothalamus, which releases Gonadotropin-Releasing Hormone (GnRH).
Here’s the sequence in detail:
1. Hypothalamus releases GnRH in a pulsatile manner.
2. GnRH stimulates the anterior pituitary gland to secrete Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH).
3. FSH promotes the growth and maturation of ovarian follicles.
4. Growing follicles start producing estrogen, which eventually leads to ovulation.
So, the starting point of the ovarian cycle is the hypothalamus, through its control of pituitary hormones.
Other Options Details
The ovarian cycle is initiated by the hypothalamus.
Here’s a detailed explanation:
1. Hypothalamus: It secretes GnRH (Gonadotropin-releasing hormone) in a pulsatile manner.
2. Anterior Pituitary: GnRH stimulates the anterior pituitary to release FSH (Follicle-stimulating hormone) and LH (Luteinizing hormone).
3. Ovaries: FSH promotes the growth and maturation of ovarian follicles, while LH triggers ovulation and formation of the corpus luteum.
So, the trigger for the ovarian cycle is GnRH secretion by the hypothalamus.
Other Options Details
Here’s a detailed explanation of each option:
A. Progesterone
• Progesterone is a steroid hormone produced mainly by the corpus luteum in the ovary after ovulation.
Functions:
• Prepares the endometrium (lining of the uterus) for implantation of a fertilized egg.
• Maintains early pregnancy.
• Inhibits further ovulation during the luteal phase.
• Helps regulate the menstrual cycle.
B. Estrogen
• Estrogen is a steroid hormone primarily produced by the developing ovarian follicles.
Functions:
• Stimulates growth of the endometrial lining during the follicular/proliferative phase.
• Promotes secondary sexual characteristics like breast development and body hair distribution.
• Regulates FSH and LH through feedback mechanisms.
• Plays a role in bone health and cardiovascular function.
C. Endorphins
Endorphins are peptides produced by the pituitary gland and hypothalamus.
Functions:
• Act as natural painkillers.
• Induce feelings of pleasure or well-being.
• Can influence stress response and mood.
• May play a minor role in reproductive function by modulating hormone release, but not directly involved in the menstrual cycle like estrogen or progesterone.
D. Follicle Stimulating Hormone (FSH)
• FSH is a gonadotropin hormone secreted by the anterior pituitary gland.
Functions:
• Stimulates the growth and maturation of ovarian follicles in females.
• Promotes estrogen production by the developing follicles.
• In males, stimulates spermatogenesis in the testes.
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Writer: Vandita Singh, Lucknow (GS India Nursing Group)