Problem 31 - Objective Biology for NEET

Question

induces ovulation of fully mature follicle (Graffian follicles) and maintains the corpus luteum, formed from the remnants of the Graffian follicles after ovulation. (a) FSH (b) ACTH (c) \(\mathrm{LH}\) (d) \(\mathrm{GH}\)

Step-by-Step Solution

Answer

The correct answer is \(\mathrm{LH}\).

Step 1: Identification of FSH

FSH, or Follicle Stimulating Hormone, is a gonadotropin that stimulates the growth and recruitment of immature ovarian follicles in the ovary. But it does not trigger ovulation or maintain the corpus luteum.

Step 2: Identification of ACTH

ACTH, or Adrenocorticotropic hormone, stimulates the adrenal glands to produce cortisol. It is not directly involved in the ovulation process or the maintenance of the corpus luteum.

Step 3: Identification of LH

LH, or Luteinizing Hormone, triggers ovulation and the formation of the corpus luteum from the remnants of the Graffian follicles post-ovulation. This fits the requirements as specified.

Step 4: Identification of GH

GH, or Growth Hormone, is responsible for facilitating cell reproduction and regeneration. It does not have a direct role in ovulation or the maintenance of the corpus luteum.

Key Concepts

Ovulation

Ovulation is a crucial phase in the female reproductive cycle. It occurs when a mature egg is released from the ovary. The process of ovulation is vital for reproduction as it provides the opportunity for fertilization by sperm.

The primary orchestrator of ovulation is the Luteinizing Hormone (LH). LH surges in the middle of the menstrual cycle which then signals the ovary to release a fully developed egg. This burst of LH is often referred to as the "LH surge." The timing of this surge is critical for successful ovulation. Here is what typically happens during ovulation:

• The mature follicle, which has been developing under the influence of the Follicle Stimulating Hormone (FSH), becomes ready.
• The LH surge prompts the release of the egg from the Graafian follicle.
• The egg travels down the fallopian tube toward the uterus.

Ovulation not only sets the stage for potential fertilization but also signals significant hormonal changes in the menstrual cycle.

Corpus Luteum

The corpus luteum plays an essential role in the menstrual cycle following ovulation. Once ovulation occurs, the remnants of the Graafian follicle transform into the corpus luteum.

The primary function of the corpus luteum is to secrete hormones, particularly progesterone and some estrogen. These hormones are crucial because:

• They maintain the uterine lining, making it suitable for potential embryo implantation.
• They help regulate the menstrual cycle and prepare the body for a possible pregnancy.

If pregnancy does not happen, the corpus luteum degenerates after approximately 14 days, leading to a drop in progesterone levels. This decrease triggers the shedding of the uterine lining, known as menstruation. Thus, the presence and function of the corpus luteum are vital for healthy reproductive function and cycle regulation.

Graafian Follicles

Graafian follicles are the fully mature ovarian follicles that have the potential to release an egg during ovulation. Throughout the early phases of the menstrual cycle, these follicles develop and prepare under the influence of FSH.

Here's how the Graafian follicles play out in the reproductive cycle:

• Several immature follicles start to develop, but usually only one reaches full maturity each month.
• As the Graafian follicle matures, it enlarges and fills with fluid, preparing for the impending ovulation.
• On the surge of LH, the fully matured Graafian follicle bursts, releasing the egg.

After the egg is released, the remnants of the burst Graafian follicle transform into the corpus luteum. This transformation marks the transition from the follicular phase of the menstrual cycle to the luteal phase. Understanding Graafian follicles is crucial for comprehending how the female body prepares for possible pregnancy each month.