Reproductive Physiology Practice Questions

Q: Which one of the following is true regarding normal menstrual physiology?

Ovulation occurs after 12 hours of LH peak. ***Ovulation occurs after 12 hours of LH peak*** - Ovulation typically occurs approximately **10-12 hours after the luteinizing hormone (LH) peak** and about 34-36 hours after the initial rise in LH. This delay allows for the final maturation of the oocyte. - The **LH surge** is the crucial hormonal signal that triggers the ovulation process in the mature follicle. *Ovulation occurs after 48 hours of LH surge* - This statement is incorrect as **ovulation occurs much sooner** after the LH surge, typically within 34-36 hours from the onset of the surge, and 10-12 hours after its peak. - A 48-hour delay would mean the oocyte would likely be past its optimal viability for fertilization. *Oestradiol levels peak at 48 hours prior to ovulation* - **Estradiol levels peak approximately 24-36 hours before ovulation**, not 48 hours. This peak in estradiol is what triggers the surge in LH. - The timing of the estradiol peak is crucial in initiating the positive feedback loop that leads to the LH surge. *LH surge duration is typically 12-24 hours* - The **LH surge typically lasts for about 48 hours**, not 12-24 hours. A surge of this duration ensures sufficient time for the final maturation of the oocyte and the process of follicular rupture. - The prolonged nature of the LH surge is essential for the completion of meiosis I in the oocyte and the weakening of the follicular wall.

Q: The amount of iron lost per 28 day cycle in menstruating women is

15.5 mg. ***15.5 mg*** - The typical **iron loss** during a 28-day menstrual cycle in menstruating women is approximately **15-28 mg**, with an average of about **15.5 mg**. - This calculation is based on average menstrual blood loss of **30-40 mL per cycle** and iron content of approximately **0.5 mg per mL of blood**. - This physiological iron loss explains why menstruating women have **higher iron requirements** (18 mg/day) compared to men (8 mg/day). - If dietary iron intake is insufficient to compensate for this loss, **iron deficiency anemia** can develop over time. *5.5 mg* - This value significantly **underestimates** the actual iron loss during menstruation. - Such a low amount would not explain the increased iron requirements in menstruating women. - This does not align with measured menstrual blood loss volumes. *8.5 mg* - This value is still **lower than the typical physiological range** of iron loss during menstruation. - While closer than 5.5 mg, it underestimates the actual iron depletion that occurs. *12.5 mg* - This value is **within the lower range** but still below the commonly accepted average. - While individual variations exist, standard teaching emphasizes higher values (15-28 mg range).

Q: A couple presented to OPD with complaint of inability to conceive for the last 3 years. Husband was advised semen analysis. What is the WHO criterion for minimum sperm count per ml in normal semen?

15 million. ***15 million*** - The **WHO 2010 criteria** for normal semen analysis specifies a lower reference limit for sperm concentration as **15 million spermatozoa per mL**. - This count is considered the minimum threshold for **normal fertility potential** according to current international guidelines. *30 million* - While a higher sperm count, **30 million** is not the minimum threshold set by the WHO for normal semen analysis. - A count of 30 million would be considered well within the normal range, but the question specifically asks for the *minimum* criterion. *40 million* - **40 million** is significantly above the minimum sperm concentration required for normal fertility as per WHO guidelines. - This higher count would indicate robust spermatogenesis but is not the lower limit for defining normalcy. *10 million* - A sperm count of **10 million spermatozoa per mL** falls below the **WHO 2010 reference range** for normal sperm concentration. - This value would likely be considered **oligozoospermia** and could indicate reduced fertility potential.

Q: Oxytocin is not responsible for:

Milk production. ***Milk production*** - **Oxytocin** is primarily responsible for the **ejection of milk** from the mammary glands, not its production. - **Prolactin** is the hormone chiefly responsible for **milk synthesis** or production. *Uterine involution* - **Oxytocin** plays a crucial role in **uterine contractions** postpartum, which helps the uterus return to its normal size (involution). - These contractions compress blood vessels, reducing **postpartum hemorrhage**. *After pains* - The contractions stimulated by **oxytocin** after childbirth, essential for uterine involution, are often perceived as **'after pains'**. - These pains are more pronounced in **multiparas** and breastfeeding women due to vigorous oxytocin release. *Milk ejection* - **Oxytocin** causes the contraction of **myoepithelial cells** surrounding the alveoli in the mammary glands. - This contraction leads to the **'let-down reflex,'** forcing milk into the ducts and outward through the nipple.

Q: Which one of the following is true about Basal body temperature? 1. Shows a biphasic pattern during menstrual cycle 2. Rises by 0.3-0.5°C after ovulation due to progesterone 3. Can be used to confirm that ovulation has occurred 4. Remains constant throughout the menstrual cycle Select the correct answer using the code given below:

1, 2 and 3. ***1, 2 and 3*** - Basal Body Temperature (BBT) exhibits a **biphasic pattern** during the menstrual cycle, with a lower temperature in the follicular phase (before ovulation) and a higher temperature in the luteal phase (after ovulation). - The rise in BBT of **0.3-0.5°C** following ovulation is a direct result of increased **progesterone** secretion from the corpus luteum, which has thermogenic properties. - BBT is a **retrospective indicator** that **confirms ovulation has occurred** by showing the sustained temperature elevation, making it useful for tracking ovulation patterns over time. *2, 3 and 4* - This option is incorrect because BBT does **not remain constant** throughout the menstrual cycle; it shows a characteristic **biphasic pattern** with lower temperatures before ovulation and higher temperatures after. *1, 3 and 4* - This option is incorrect because statement 4 is false - BBT does **not remain constant** but rather demonstrates a **biphasic shift** with a temperature rise after ovulation. *All of the above* - This option is incorrect because statement 4 is false - BBT shows a **biphasic pattern**, not a constant temperature throughout the cycle.

Q: Which of the following prevents polyspermy?

Cortical reaction. ***Cortical reaction*** - The **cortical reaction** is the primary mechanism that prevents **polyspermy** following sperm-oocyte fusion. - Upon fusion, **cortical granules** in the oocyte cytoplasm release their contents (including proteases and peroxidases) into the **perivitelline space**. - These enzymes modify the **zona pellucida** proteins, making it impermeable to additional sperm - this modification is called the **zona reaction**. - The cortical reaction represents both the **fast block** (depolarization of oocyte membrane) and **slow block** (zona pellucida hardening) to polyspermy. *Zona reaction* - The **zona reaction** is the biochemical and structural change that occurs in the zona pellucida as a **result** of the cortical reaction. - It involves hardening and altered permeability of the zona pellucida, making it resistant to sperm penetration. - While this is the ultimate barrier to polyspermy, it is a **consequence** rather than the active mechanism - the cortical reaction is the causative event. *Acrosome reaction* - The **acrosome reaction** is essential for fertilization, allowing sperm to penetrate the zona pellucida by releasing hydrolytic enzymes. - It **facilitates** sperm entry rather than preventing additional sperm from binding. - This reaction must occur for the first sperm to fertilize the egg but plays no role in preventing polyspermy. *Capacitation* - **Capacitation** is the physiological maturation of sperm in the female reproductive tract. - It enables sperm to undergo the acrosome reaction and achieve fertilization competence. - It is a preparatory process and has no role in preventing polyspermy.

Q: After ovulation, the oocyte is:

Secondary oocyte arrested in metaphase II. ***Secondary oocyte arrested in metaphase II*** - After ovulation, the **oocyte** has completed **meiosis I** and extruded the **first polar body**, becoming a secondary oocyte. - It then arrests in **metaphase II** and will only complete meiosis II upon fertilization by a sperm. *Primary oocyte arrested in prophase II* - A **primary oocyte** is the stage before meiosis I is completed, and it is arrested in **prophase I** at birth, not prophase II. - Oocytes do not arrest in **prophase II** during normal meiotic development. *Secondary oocyte arrested in prophase II* - While it is a **secondary oocyte** that is ovulated, it is arrested in **metaphase II**, not prophase II. - **Prophase II** is a transient stage that occurs just before metaphase II, and arrest at this stage is not typical for the ovulated oocyte. *Primary oocyte arrested in prophase I* - This describes the state of the oocyte from **fetal development** until just before ovulation. - A **primary oocyte** completes meiosis I only in response to the **LH surge** before ovulation.

Q: Absence or mutation of SRY gene results in ?

Gonadal dysgenesis. ***Gonadal dysgenesis*** - The **SRY gene** (Sex-determining region Y gene) is critical for initiating **male sexual differentiation**; its presence leads to testicular development. - Absence or mutation of the SRY gene prevents proper testicular development, leading to **gonadal dysgenesis**, where the gonads are either absent or rudimentary, often resulting in a **female phenotype** despite a XY genotype. *Hydrocele testis* - This condition involves an accumulation of fluid around the testis, which is typically due to a **patent tunica vaginalis** or fluid imbalance. - It does not directly result from a genetic mutation in the SRY gene affecting initial **gonadal development**. *Undescended testis* - This condition (cryptorchidism) refers to the failure of one or both testes to descend into the scrotum. - While it can have genetic components, it is not a direct consequence of an SRY gene absence or mutation, which primarily affects the **formation of the gonad itself**. *None of the options* - This option is incorrect because **gonadal dysgenesis** is a direct and well-established consequence of SRY gene absence or mutation. - The SRY gene's primary role is to trigger the development of the testis, and its dysfunction leads to profound abnormalities in **gonadal formation**.

Q: Milk production in pregnancy is inhibited by :

High estrogen. ***High estrogen*** - High levels of **estrogen** and progesterone during pregnancy inhibit milk production by blocking the action of **prolactin** on the mammary glands. - After delivery, the sudden drop in these hormones removes the inhibition, allowing prolactin to stimulate **lactogenesis**. *Low luteinizing hormone* - **Luteinizing hormone (LH)** is primarily involved in ovulation and corpus luteum formation, not directly in the inhibition of milk production. - Low LH levels would impact fertility but not have a direct inhibitory effect on lactation. *Low thyroid-stimulating hormone* - **Thyroid-stimulating hormone (TSH)** regulates thyroid function, which can indirectly affect metabolism and overall well-being. - While **hypothyroidism** can impact milk supply, low TSH itself is not a direct inhibitor of milk production. *Human somatomammotropin* - **Human placental lactogen (HPL)**, also known as human chorion somatomammotropin, is produced by the placenta. - It promotes mammary gland development and has weak lactogenic properties but does not inhibit milk production.

Q: Which hormone is primarily responsible for initiating milk production postpartum?

Prolactin. ***Prolactin*** - **Prolactin** is the primary hormone responsible for **milk production (lactogenesis)** by stimulating alveolar epithelial cells in the mammary glands. - Its levels rise significantly after childbirth, especially after the expulsion of the placenta, which leads to a drop in inhibitory hormones like progesterone. *Estrogen* - **Estrogen** plays a role in the **growth and development of the mammary glands** during pregnancy but inhibits milk production during gestation. - High estrogen levels during pregnancy prevent prolactin from fully initiating lactation, and their sharp drop postpartum helps trigger milk synthesis. *Oxytocin* - **Oxytocin** is crucial for **milk ejection (let-down reflex)**, causing myoepithelial cells around the alveoli to contract and release milk. - It does not directly cause milk production but rather aids in the release of milk that has already been synthesized. *Progesterone* - **Progesterone** is essential for the **development of the mammary glands** during pregnancy, contributing to alveolar growth. - High levels of progesterone during pregnancy, along with estrogen, actually **inhibit** the full effect of prolactin, preventing milk production until after birth when these hormone levels drop.

Question 1

Which one of the following is true regarding normal menstrual physiology?

Accepted Answer

Ovulation occurs after 12 hours of LH peak

Answer

Ovulation occurs after 48 hours of LH surge

Answer

Oestradiol levels peak at 48 hours prior to ovulation

Answer

LH surge duration is typically 12-24 hours

Question 2

The amount of iron lost per 28 day cycle in menstruating women is

Accepted Answer

15.5 mg

Answer

8.5 mg

Answer

12.5 mg

Answer

5.5 mg

Question 3

A couple presented to OPD with complaint of inability to conceive for the last 3 years. Husband was advised semen analysis. What is the WHO criterion for minimum sperm count per ml in normal semen?

Accepted Answer

15 million

Answer

30 million

Answer

40 million

Answer

10 million

Question 4

Oxytocin is not responsible for:

Accepted Answer

Milk production

Answer

Uterine involution

Answer

After pains

Answer

Milk ejection

Question 5

Which one of the following is true about Basal body temperature?
1. Shows a biphasic pattern during menstrual cycle
2. Rises by 0.3-0.5°C after ovulation due to progesterone
3. Can be used to confirm that ovulation has occurred
4. Remains constant throughout the menstrual cycle
Select the correct answer using the code given below:

Accepted Answer

1, 2 and 3

Answer

2, 3 and 4

Answer

1, 3 and 4

Answer

All of the above

Question 6

Which of the following prevents polyspermy?

Accepted Answer

Cortical reaction

Answer

Acrosome reaction

Answer

Zona reaction

Answer

Capacitation

Question 7

After ovulation, the oocyte is:

Accepted Answer

Secondary oocyte arrested in metaphase II

Answer

Primary oocyte arrested in prophase II

Answer

Secondary oocyte arrested in prophase II

Answer

Primary oocyte arrested in prophase I

Question 8

Absence or mutation of SRY gene results in ?

Accepted Answer

Gonadal dysgenesis

Answer

Hydrocele testis

Answer

Undescended testis

Answer

None of the options

Question 9

Milk production in pregnancy is inhibited by :

Accepted Answer

High estrogen

Answer

Low luteinizing hormone

Answer

Low thyroid-stimulating hormone

Answer

Human somatomammotropin

Question 10

Which hormone is primarily responsible for initiating milk production postpartum?

Accepted Answer

Prolactin

Answer

Estrogen

Answer

Oxytocin

Answer

Progesterone

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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