Reproductive Physiology Practice Questions

Q: Ovulation is due to surge of:

LH. **Explanation:** The correct answer is **LH (Luteinizing Hormone)**. **Mechanism of Ovulation:** Ovulation is primarily triggered by the **LH surge**. In the late follicular phase, rising levels of Estrogen (secreted by the dominant Graafian follicle) exert a **positive feedback** effect on the anterior pituitary once a threshold level (>200 pg/mL for ~48 hours) is reached. This results in a massive release of LH. The LH surge initiates the final maturation of the oocyte, stimulates the production of proteolytic enzymes (like collagenase) to weaken the follicular wall, and induces the rupture of the follicle, releasing the secondary oocyte. **Analysis of Incorrect Options:** * **FSH (Follicle Stimulating Hormone):** While there is a simultaneous FSH surge (due to GnRH stimulation), its primary role is the recruitment and growth of ovarian follicles. It is not the primary trigger for the rupture of the follicle. * **Prolactin:** High levels of prolactin actually *inhibit* ovulation by suppressing GnRH secretion, which is why hyperprolactinemia often leads to amenorrhea and infertility. * **TSH (Thyroid Stimulating Hormone):** TSH regulates thyroid function. While thyroid disorders can affect the menstrual cycle, TSH has no direct role in the acute process of ovulation. **High-Yield NEET-PG Pearls:** * **Timing:** Ovulation occurs approximately **24–36 hours after the LH surge** begins and **10–12 hours after the LH peak**. * **Meiosis:** The LH surge triggers the completion of **Meiosis I** (converting the primary oocyte to a secondary oocyte) and arrests the cell in **Metaphase of Meiosis II**. * **Predictor:** Measuring urinary LH levels is the most reliable clinical method for predicting the timing of ovulation in fertility monitoring.

Q: Hormones FSH and LH of the anterior pituitary gland act on which of the following?

Both testis and ovaries. ### Explanation **Core Concept: The Hypothalamic-Pituitary-Gonadal (HPG) Axis** FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone) are collectively known as **gonadotropins**. They are synthesized and secreted by the gonadotroph cells of the anterior pituitary in response to GnRH from the hypothalamus. Their primary physiological role is to regulate the function of the **gonads** (both testes and ovaries), making Option C the correct answer. **Mechanism of Action:** * **In Females (Ovaries):** FSH stimulates the growth of ovarian follicles and the activity of aromatase (converting androgens to estrogens). LH triggers ovulation and maintains the corpus luteum for progesterone production. * **In Males (Testis):** FSH acts on **Sertoli cells** to support spermatogenesis. LH acts on **Leydig cells** to stimulate testosterone production. **Analysis of Incorrect Options:** * **Options A & B:** These are incorrect because gonadotropins are not sex-specific; they are essential for reproductive function in both males and females. * **Option D:** The adrenal cortex is primarily regulated by **ACTH** (Adrenocorticotropic Hormone) for cortisol production and the Renin-Angiotensin-Aldosterone System (RAAS) for mineralocorticoids. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Male Action:** **L**H acts on **L**eydig cells (Testosterone); **S**FSH acts on **S**ertoli cells (Spermatogenesis). * **Two-Cell, Two-Gonadotropin Theory:** In the ovary, LH stimulates Theca cells (Androstenedione production), while FSH stimulates Granulosa cells (Conversion to Estradiol). * **Inhibin:** Produced by Sertoli cells (males) and Granulosa cells (females), it provides negative feedback specifically to **FSH**, not LH. * **Pulsatility:** GnRH must be secreted in a pulsatile manner; continuous infusion paradoxically suppresses FSH and LH (the basis for GnRH agonist therapy in prostate cancer and endometriosis).

Q: Which of the following is NOT a feature of inhibin?

Stimulates FSH secretion. **Explanation:** **Inhibin** is a glycoprotein hormone that plays a critical role in the negative feedback regulation of the hypothalamic-pituitary-gonadal axis. **Why Option C is the correct answer (The "NOT" feature):** The primary physiological function of inhibin is to **selectively inhibit** the secretion of **Follicle-Stimulating Hormone (FSH)** from the anterior pituitary. It does not stimulate FSH. This feedback loop is essential for regulating follicular development in females and spermatogenesis in males. **Analysis of other options:** * **Option A:** Inhibin is indeed a **non-steroidal, water-soluble glycoprotein** composed of an alpha and a beta subunit ($\alpha\beta$). * **Option B:** In females, it is primarily secreted by the **granulosa cells** of the developing antral follicles and the **Graafian follicle**. In males, it is secreted by the **Sertoli cells**. * **Option D:** In **Polycystic Ovarian Disease (PCOD/PCOS)**, there is an increased number of small antral follicles. This leads to **elevated levels of Inhibin-B**, which contributes to the characteristic suppression of FSH seen in these patients (leading to a high LH:FSH ratio). **High-Yield Clinical Pearls for NEET-PG:** * **Inhibin A vs. B:** Inhibin **B** is the primary form in the follicular phase (marker of ovarian reserve), while Inhibin **A** peaks in the luteal phase (secreted by the corpus luteum). * **Tumor Marker:** Inhibin is a highly specific tumor marker for **Granulosa Cell Tumors** of the ovary. * **Triple/Quadruple Test:** Inhibin A is measured during the second trimester of pregnancy; **elevated levels** are associated with an increased risk of **Down Syndrome (Trisomy 21)**. * **Activin:** A related protein (beta-beta dimer) that performs the opposite function—it **stimulates** FSH secretion.

Q: Sertoli cells have receptors for which of the following hormones?

Follicle stimulating hormone. **Explanation:** The correct answer is **Follicle Stimulating Hormone (FSH)**. Sertoli cells, often called "nurse cells," are located within the seminiferous tubules and are essential for spermatogenesis. **1. Why FSH is correct:** Sertoli cells are the primary targets for FSH in the male reproductive system. When FSH binds to its G-protein coupled receptors on the Sertoli cell membrane, it stimulates the production of **Androgen Binding Protein (ABP)**, which maintains high local testosterone levels, and **Inhibin**, which provides negative feedback to the anterior pituitary. FSH also promotes the synthesis of nutrients and growth factors required for the maturation of germ cells. **2. Why other options are incorrect:** * **Inhibin:** This is a hormone **produced by** Sertoli cells, not one they have receptors for. It acts on the anterior pituitary to specifically inhibit FSH secretion. * **Luteinizing Hormone (LH):** LH receptors are located on **Leydig cells** (interstitial cells), where LH stimulates the production of testosterone. A common mnemonic is **L**H acts on **L**eydig cells. * **Melatonin:** While melatonin can influence the hypothalamic-pituitary-gonadal axis (typically inhibitory), Sertoli cells are not its primary physiological target in the context of direct hormonal regulation of spermatogenesis. **Clinical Pearls for NEET-PG:** * **Blood-Testis Barrier:** Formed by tight junctions between adjacent Sertoli cells; it protects developing sperm from the immune system. * **Müllerian Inhibiting Substance (MIS):** Also secreted by Sertoli cells in the fetus to cause regression of Müllerian ducts. * **Spermiation:** The process of releasing mature spermatozoa from Sertoli cells into the lumen of seminiferous tubules. * **Hormonal Control:** Spermatogenesis requires both **FSH** (acting on Sertoli cells) and **Testosterone** (produced by Leydig cells under LH influence).

Q: What is the normal pH range of amniotic fluid?

7.4 to 7.6. **Explanation:** The correct answer is **C (7.4 to 7.6)**. Amniotic fluid is a dynamic medium that surrounds the fetus, serving protective and metabolic functions. In a normal pregnancy, amniotic fluid is **slightly alkaline**, with a pH ranging from 7.0 to 7.5, typically stabilizing between **7.4 and 7.6**. This alkalinity is primarily due to the composition of the fluid, which includes fetal urine (which becomes less acidic as the kidneys mature) and secretions from the fetal respiratory tract and umbilical cord. **Analysis of Options:** * **Options A and D (6.7 to 6.9):** These values are acidic. Amniotic fluid is not normally acidic. In fact, the alkaline nature of amniotic fluid is a key diagnostic feature used to distinguish it from vaginal secretions (which are acidic, pH 3.8–4.5) during a Nitrazine test for the rupture of membranes. * **Option B (8.1 to 8.3):** This range is too basic. While the fluid is alkaline, it does not reach such high levels under physiological conditions. **Clinical Pearls for NEET-PG:** 1. **Nitrazine Test:** This is a high-yield clinical application. When amniotic fluid (pH >7.0) leaks into the vagina, it turns Nitrazine paper from yellow to **blue**. 2. **Fern Test:** Due to the high concentration of sodium chloride, amniotic fluid creates a "ferning" pattern when dried on a slide, confirming the Rupture of Membranes (ROM). 3. **Volume Dynamics:** Amniotic fluid volume peaks at approximately **800–1000 ml at 34–36 weeks** and decreases to about 600 ml at term (40 weeks). 4. **Specific Gravity:** It has a low specific gravity, approximately **1.008 to 1.010**.

Q: What is the action of oxytocin, except?

Contraction of the lower uterine segment. ### Explanation Oxytocin is a peptide hormone synthesized in the **paraventricular nucleus** of the hypothalamus and secreted by the posterior pituitary. Its primary role is to stimulate smooth muscle contraction in specific reproductive tissues. **Why Option D is the Correct Answer:** During labor, oxytocin promotes **fundal dominance**. It causes strong, rhythmic contractions of the **upper segment** of the uterus (the fundus and body) while simultaneously causing the **lower uterine segment to relax and thin out**. This physiological gradient is essential to push the fetus downward and allow the cervix to dilate. If the lower segment contracted along with the upper segment, the fetus would be trapped, and the cervix would not dilate. **Analysis of Incorrect Options:** * **Option A (Increased contractility):** Oxytocin increases the force and frequency of uterine contractions by increasing intracellular calcium and stimulating prostaglandin synthesis. * **Option B & C (Myoepithelial cells/Milk ejection):** Oxytocin causes the contraction of **myoepithelial cells** surrounding the mammary alveoli. This forces milk into the larger ducts and out through the nipple, a process known as the **Milk Ejection Reflex** (or "let-down" reflex). **High-Yield Clinical Pearls for NEET-PG:** * **Ferguson Reflex:** A neuroendocrine reflex where vaginal/cervical stretching triggers oxytocin release, creating a positive feedback loop during labor. * **Receptor Regulation:** Estrogen **upregulates** oxytocin receptors (increasing sensitivity at term), while progesterone **downregulates** them. * **Clinical Use:** Synthetic oxytocin (Pitocin) is the drug of choice for **Induction of Labor** and the prevention/treatment of **Postpartum Hemorrhage (PPH)**. * **Side Effect:** At high doses, oxytocin has an **ADH-like effect**, which can lead to water intoxication and hyponatremia.

Q: Which of the following can be used to evaluate ovulation?

Cervical mucous. **Explanation:** The correct answer is **Cervical mucous**. Evaluation of cervical mucus is a reliable clinical indicator of the ovulatory phase due to the influence of fluctuating ovarian hormones. 1. **Why Cervical Mucous is Correct:** Under the influence of high **estrogen** levels just before ovulation, the cervical mucus undergoes characteristic changes to facilitate sperm transport. It becomes **profuse, thin, watery, and alkaline**. Two specific tests evaluate this: * **Spinnbarkeit Effect:** The mucus becomes highly elastic and can be stretched into a long thread (usually >6 cm). * **Ferning Pattern:** When dried on a slide, the high sodium chloride content causes the mucus to crystallize in a "fern-like" pattern. Post-ovulation, progesterone makes the mucus thick, tacky, and cellular, abolishing these features. 2. **Why Other Options are Incorrect:** * **Cervical Colour:** Changes in cervical color (e.g., **Chadwick’s sign**, where the cervix turns bluish) are signs of increased vascularity associated with **pregnancy**, not ovulation. * **Cervical Dilation and Effacement:** These are clinical parameters used to assess the progress of **labor**. While minor softening occurs during ovulation, dilation and effacement are not standard or reliable methods for evaluating the ovulatory cycle. **High-Yield Clinical Pearls for NEET-PG:** * **Best indicator of ovulation:** Mid-luteal phase **Serum Progesterone** levels (>3 ng/ml). * **Gold standard for timing ovulation:** Serial Transvaginal Ultrasound (TVS) to monitor follicular disappearance. * **LH Surge:** Occurs 24–36 hours before ovulation; it is the basis for home ovulation predictor kits. * **Basal Body Temperature (BBT):** Increases by 0.5–1.0°F after ovulation due to the thermogenic effect of progesterone.

Q: If the corpus luteum is functioning, its endocrine function is initiated by the influence of which of the following hormones?

LH. **Explanation:** The **Corpus Luteum (CL)** is a temporary endocrine structure formed from the remnants of the Graafian follicle after ovulation. Its primary function is the secretion of progesterone and estrogen to maintain the endometrial lining for potential implantation. **Why LH is the Correct Answer:** The initiation and maintenance of the corpus luteum are strictly dependent on **Luteinizing Hormone (LH)**. Following the LH surge, which triggers ovulation, the remaining granulosa and theca cells undergo "luteinization." LH stimulates these cells to increase their expression of steroidogenic enzymes, effectively turning the follicle into a progesterone-producing factory. Without the continuous trophic support of LH (or hCG in pregnancy), the corpus luteum would undergo luteolysis (degeneration). **Why Other Options are Incorrect:** * **FSH (Follicle Stimulating Hormone):** While FSH is crucial for the recruitment and growth of follicles during the follicular phase, it does not initiate the endocrine function of the corpus luteum. * **GnRH (Gonadotropin-Releasing Hormone):** GnRH is the upstream hypothalamic hormone that stimulates the release of LH and FSH from the anterior pituitary. It does not act directly on the ovary to initiate luteal function. **High-Yield Clinical Pearls for NEET-PG:** * **Luteal Phase Length:** The lifespan of the corpus luteum is remarkably constant at approximately **14 days** in a non-pregnant cycle. * **Rescue of Corpus Luteum:** If fertilization occurs, **hCG** (Human Chorionic Gonadotropin), which is an analog of LH, binds to LH receptors to "rescue" the corpus luteum, maintaining progesterone production until the placenta takes over (the **luteal-placental shift** at 7–9 weeks). * **Hormone Secretion:** The corpus luteum secretes **Progesterone** (predominant), Estrogen, and **Inhibin A**.

Question 1

When there is no fertilization of the ovum, the endometrial cells undergo apoptosis because:

Accepted Answer

The involution of the corpus luteum causes estradiol and progesterone levels to fall dramatically.

Answer

LH levels rise after ovulation.

Answer

Estradiol levels are not involved in the LH surge phenomenon.

Answer

Estradiol inhibits the induction of the progesterone receptor in the endometrium.

Question 2

Ovulation is due to surge of:

Accepted Answer

LH

Answer

FSH

Answer

Prolactin

Answer

TSH

Question 3

Hormones FSH and LH of the anterior pituitary gland act on which of the following?

Accepted Answer

Both testis and ovaries

Answer

Testis but not ovaries

Answer

Ovaries but not testis

Answer

Adrenal cortex

Question 4

Which of the following is NOT a feature of inhibin?

Accepted Answer

Stimulates FSH secretion

Answer

Non-steroidal water-soluble protein

Answer

Secreted by Graafian follicle

Answer

Increased secretion of inhibin occurs in polycystic ovarian disease

Question 5

Arrange the steps of spermatogenesis in the sequence of their formation.

Accepted Answer

Spermatogonium > Spermatocyte > Spermatid > Spermatozoa

Answer

Spermatocyte > Spermatogonium > Spermatid > Spermatozoa

Answer

Spermatogonium > Spermatocyte > Spermatozoa > Spermatid

Answer

Spermatozoa > Spermatogonium > Spermatocyte > Spermatid

Question 6

Sertoli cells have receptors for which of the following hormones?

Accepted Answer

Follicle stimulating hormone

Answer

Inhibin

Answer

Luteinizing hormone

Answer

Melatonin

Question 7

What is the normal pH range of amniotic fluid?

Accepted Answer

7.4 to 7.6

Answer

6.8 to 6.9

Answer

8.1 to 8.3

Answer

6.7 to 6.8

Question 8

What is the action of oxytocin, except?

Accepted Answer

Contraction of the lower uterine segment

Answer

Increased contractility of the uterus

Answer

Contraction of myoepithelial cells

Answer

Milk ejection

Question 9

Which of the following can be used to evaluate ovulation?

Accepted Answer

Cervical mucous

Answer

Cervical colour

Answer

Cervical dilation

Answer

Cervical effacement

Question 10

If the corpus luteum is functioning, its endocrine function is initiated by the influence of which of the following hormones?

Accepted Answer

LH

Answer

FSH

Answer

GnRH

Answer

All of the above

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

On this page

Practice by Chapter

Want unlimited practice?