Reproductive Physiology Practice Questions

Q: Which among the following hormones acts on post ovulatory endometrium?

Progesterone. ***Progesterone*** - It is predominantly secreted by the **corpus luteum** during the post-ovulatory phase, inducing the crucial changes of the **secretory endometrium** to facilitate implantation.- Progesterone causes the endometrial glands to become highly **coiled** and secretory, leading to the development of **spiral arteries** and preparing the uterine lining for a fertilized ovum.*Luteinizing hormone* - LH's main role is triggering **ovulation** via the mid-cycle surge and maintaining the function of the **corpus luteum** post-ovulation.- Its primary targets are ovarian cells (theca and corpus luteum), not the direct transformation of the post-ovulatory endometrial structure.*Follicular stimulating hormone* - FSH functions primarily during the preceding **follicular phase**, stimulating the growth of ovarian follicles and inducing **estrogen** synthesis.- Its levels decrease significantly after ovulation, and it has no direct, major trophic effect on the secretory endometrium.*Oestrogen* - **Oestrogen** is the primary hormone responsible for the **proliferative phase** (pre-ovulatory), causing endometrial thickening and repair.- While necessary for endometrial primedness, Oestrogen is superseded by **Progesterone** in dictating the specific glandular and vascular characteristics of the post-ovulatory secretory phase.

Q: Which among the following hormones, in a lactating mother, is responsible for the maintenance and proliferation of milk-secreting breast tissue?

Prolactin. ***Prolactin***- **Prolactin** is the key hormone responsible for establishing and maintaining **lactation** (milk production), and it drives the final proliferation and differentiation of the **alveolar epithelial cells** during the later stages of pregnancy and postpartum state.- While other hormones contribute to overall breast development, Prolactin ensures the functional readiness and continued growth/maintenance of the glandular tissue necessary for milk synthesis.*Oxytocin*- **Oxytocin** is responsible for the **milk ejection reflex** (let-down), causing the contraction of **myoepithelial cells** around the alveoli.- It does not promote the proliferative growth or differentiation of the secretory breast tissue itself.*Estrogen*- **Estrogen** is primarily responsible for the growth and development of the **ductal system** of the breast during puberty and pregnancy.- High levels of estrogen during pregnancy actively **inhibit** the full secretory function of prolactin until after delivery.*Progesterone*- **Progesterone** is crucial for the development of the **lobular-alveolar system** during pregnancy.- Its rapid decline after delivery is essential to remove the inhibitory block, allowing **prolactin** to fully initiate and manage milk secretion in the lactating phase.

Q: Hormone responsible for milk ejection reflex in the image shown?

Oxytocin. ***Oxytocin*** - The image shows a baby breastfeeding, which involves the **suckling reflex**. This reflex triggers the release of oxytocin from the posterior pituitary gland. - Oxytocin is crucial for the **milk ejection reflex** (or let-down reflex), as it causes the contraction of myoepithelial cells surrounding the alveoli in the mammary glands, expelling milk. *TSH* - Thyroid-Stimulating Hormone (TSH) is released from the anterior pituitary and its primary role is to stimulate the **thyroid gland** to produce thyroid hormones. - It is involved in regulating the body's **metabolism** and is not directly responsible for lactation. *GH* - Growth Hormone (GH) is secreted by the anterior pituitary and is essential for overall **somatic growth**, particularly of bones and muscles. - While it contributes to mammary gland development, it does not mediate the immediate process of milk ejection during breastfeeding. *FSH* - Follicle-Stimulating Hormone (FSH) is an anterior pituitary hormone that plays a key role in the reproductive cycle. - It stimulates the growth of **ovarian follicles** in females and **spermatogenesis** in males, and is not involved in lactation.

Q: During spermatogenesis, which of the following hormones inhibits Follicle-Stimulating Hormone (FSH) secretion?

Inhibin. ***Inhibin*** - **Inhibin** is produced by **Sertoli cells** in the seminiferous tubules, acting as a crucial regulator of spermatogenesis. - It specifically targets the anterior pituitary gland to implement a **negative feedback loop**, reducing the secretion of **FSH** (Follicle-Stimulating Hormone) when sperm production levels are adequate. *Testosterone* - **Testosterone** is the primary androgen required for the maintenance and stimulation of spermatogenesis within the seminiferous tubules. - High systemic levels of testosterone primarily inhibit the secretion of **GnRH** (from the hypothalamus) and **LH** (from the pituitary), rather than specifically inhibiting FSH production. *Luteinizing Hormone (LH)* - **LH** acts on the **Leydig cells** in the testes, stimulating them to produce testosterone. - It does not directly inhibit FSH; rather, it is part of the **Hypothalamic-Pituitary-Gonadal (HPG) axis** regulation system. *Estrogen* - While small amounts of **estrogen** are produced in males (via aromatization of testosterone), it does not play a primary role in the negative feedback inhibition of FSH during spermatogenesis. - In males, **inhibin** is the specific hormone that directly targets FSH secretion from the anterior pituitary.

Q: What is the cause of LH (Luteinizing Hormone) surge?

Estradiol. ***Estradiol*** - The cause of LH surge- During the late follicular phase, the dominant follicle secretes increasingly high levels of **Estradiol** (a potent estrogen). When these levels remain high for a prolonged period (typically 48–50 hours) above a critical threshold, it switches from exerting negative feedback to **positive feedback** on the hypothalamus and anterior pituitary. - This positive feedback stimulates a massive release of **GnRH** and, subsequently, a sudden, sharp, increase in **LH** secretion, known as the LH surge, which prepares the dominant follicle for ovulation. *FSH* - FSH is essential for initiating the **follicular development** (growth and maturation of ovarian follicles) preceding the surge, but it is not the direct trigger for the LH surge. - Although FSH levels also rise slightly during the surge (known as the **FSH surge**), this rise is secondary to the primary positive feedback mechanism driven by Estradiol. *Progesterone* - Progesterone levels are typically low during the late follicular phase when the LH surge occurs; its primary rise happens **after ovulation** during the luteal phase. - While Progesterone contributes to the total feedback loop around the surge, it cannot initiate the surge itself, and its main role is preparing the **endometrium** and supporting a potential pregnancy. *LH* - LH (*Luteinizing hormone*) is the hormone whose concentration surges; it is the **effect** of the positive feedback loop, not the underlying cause. - The rise in LH concentration is a direct response of the **anterior pituitary** to the high levels of Estradiol acting upon it.

Q: In a woman with a regular 28-day menstrual cycle, which of the following best describes the typical hormonal profile during days 21 to 25 of the cycle?

High estrogen, high progesterone. ***High estrogen, high progesterone*** - Days 21 to 25 fall within the **mid-to-late luteal phase** of a 28-day cycle, which is dominated by the corpus luteum. - The corpus luteum secretes large amounts of **progesterone** (peak luteal levels) and **moderate-to-high levels of estrogen** (secondary luteal peak). - Both hormones exert **negative feedback** on the hypothalamus and pituitary, leading to suppressed **LH and FSH** levels. - This combination of high progesterone with moderately elevated estrogen is characteristic of a functional corpus luteum during the mid-luteal phase. *Low estrogen, high progesterone, low LH and FSH* - While **LH and FSH** are correctly low due to negative feedback, and **progesterone** is high, describing estrogen as "low" is inaccurate for days 21–25. - During the mid-luteal phase, the corpus luteum produces a **secondary estrogen peak** that is moderate-to-high, not low. - Low estrogen would only occur if the corpus luteum had already regressed, which happens closer to menstruation (days 26–28). *Low estrogen, high progesterone, high LH and FSH* - High levels of **LH and FSH** occur only during the **LH surge** around day 14 (ovulation) or during the **menstrual/early follicular phase** when steroid hormones are low. - The combination of **high progesterone** and **high gonadotropins** does not occur normally in the menstrual cycle, as progesterone and estrogen suppress LH and FSH through negative feedback. *Low estrogen, low progesterone, low LH and FSH* - This hormonal profile is characteristic of the **late follicular phase** before the LH surge, or the very end of the luteal phase when the corpus luteum regresses. - During days 21–25, the **corpus luteum** is still fully functional, maintaining high levels of **progesterone** and moderate-to-high levels of **estrogen**.

Q: Which feedback hormone is marked as $X$ ?

Estrogen/Testosterone. ***Estrogen/Testosterone*** - The diagram illustrates the **hypothalamic-pituitary-gonadal axis**, where GnRH from the hypothalamus stimulates LH and FSH from the anterior pituitary, which in turn act on the gonads. - The hormone marked 'X' represents the **negative feedback** from the gonadal hormones (estrogen in females, testosterone in males) on the anterior pituitary and hypothalamus, inhibiting further release of LH, FSH, and GnRH. *Progesterone* - While progesterone is a gonadal hormone and exerts negative feedback, it is typically involved alongside estrogen in the **luteal phase** of the menstrual cycle, and 'X' represents the general feedback from the primary sex steroids. - In males, progesterone is not the primary feedback hormone. *Inhibin* - Inhibin is a peptide hormone produced by the gonads that primarily exerts **negative feedback on FSH secretion** from the anterior pituitary, not on LH or GnRH to the same extent. - The feedback denoted by 'X' appears to be a **broader inhibitory signal** encompassing both LH and FSH regulation. *Activin* - Activin is a protein complex that generally **stimulates FSH secretion** from the anterior pituitary, playing an antagonistic role to inhibin. - It does not exert negative feedback on the pituitary or hypothalamus, making it an unlikely candidate for 'X'.

Q: Carbohydrate metabolism in normal pregnancy shows :

Fasting hypoglycaemia. ***Fasting hypoglycaemia*** - Due to the **fetus continuously drawing glucose** from the mother's circulation, the mother's glucose levels can fall between meals or during prolonged fasting. - This is exacerbated by the **increased insulin secretion** in early pregnancy and **increased peripheral glucose utilization**. *Decreased plasma glucagon levels* - Plasma **glucagon levels are generally increased** or unchanged in normal pregnancy to counteract the tendency towards hypoglycemia. - Glucagon helps **mobilize glucose from liver stores** to maintain maternal blood glucose levels. *Postprandial hypoglycaemia* - Pregnancy is typically characterized by **postprandial hyperglycemia** due to increased insulin resistance later in pregnancy and a slower insulin response. - The delayed insulin response means that glucose levels can rise higher after a meal before insulin restores them to normal. *Increased sensitivity of insulin receptors in mother* - In normal pregnancy, especially in the **second and third trimesters**, there is a physiologic **decrease in maternal insulin sensitivity**. - This **insulin resistance**, mediated by placental hormones, ensures adequate glucose supply to the fetus.

Question 1

The placenta secretes a hormone that is utilized in the early detection of pregnancy. This hormone is:

Accepted Answer

Human chorionic gonadotropin (hCG)

Answer

Endothelial growth factor (EGF)

Answer

Human chorionic somatotropin (HCS)

Answer

Relaxin

Question 2

Which among the following hormones acts on post ovulatory endometrium?

Accepted Answer

Progesterone

Answer

Follicle stimulating hormone

Answer

Luteinizing hormone

Answer

Oestrogen

Question 3

Which among the following hormones, in a lactating mother, is responsible for the maintenance and proliferation of milk-secreting breast tissue?

Accepted Answer

Prolactin

Answer

Estrogen

Answer

Oxytocin

Answer

Progesterone

Question 4

Hormone responsible for milk ejection reflex in the image shown?

Accepted Answer

Oxytocin

Answer

GH

Answer

TSH

Answer

FSH

Question 5

During spermatogenesis, which of the following hormones inhibits Follicle-Stimulating Hormone (FSH) secretion?

Accepted Answer

Inhibin

Answer

Luteinizing Hormone (LH)

Answer

Testosterone

Answer

Estrogen

Question 6

What is the cause of LH (Luteinizing Hormone) surge?

Accepted Answer

Estradiol

Answer

LH

Answer

Progesterone

Answer

FSH

Question 7

In a woman with a regular 28-day menstrual cycle, which of the following best describes the typical hormonal profile during days 21 to 25 of the cycle?

Accepted Answer

High estrogen, high progesterone

Answer

Low estrogen, high progesterone, high LH and FSH

Answer

Low estrogen, low progesterone, low LH and FSH

Answer

Low estrogen, high progesterone, low LH and FSH

Question 8

Which feedback hormone is marked as $X$ ?

Accepted Answer

Estrogen/Testosterone

Answer

Progesterone

Answer

Inhibin

Answer

Activin

Question 9

Carbohydrate metabolism in normal pregnancy shows :

Accepted Answer

Fasting hypoglycaemia

Answer

Decreased plasma glucagon levels

Answer

Postprandial hypoglycaemia

Answer

Increased sensitivity of insulin receptors in mother

Question 10

Onset of labour is initiated by which of the following?

Accepted Answer

Increased synthesis of myometrial receptors for oxytocin due to effect of oestrogen

Answer

Increased level of progesterone immediately before labour

Answer

Uterine distension

Answer

Increased CRH and ACTH from foetal hypothalamic-pituitary-adrenal axis

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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