Reproductive Physiology Practice Questions

Q: Which of the following is true about obstructive azoospermia?

Normal FSH and normal LH. In reproductive physiology, azoospermia is classified into two main types: **Pre-testicular/Testicular (Non-obstructive)** and **Post-testicular (Obstructive)**. ### **Explanation of the Correct Answer** In **Obstructive Azoospermia**, the hypothalamic-pituitary-testicular axis is intact, and spermatogenesis (sperm production) within the testes is typically normal. The absence of sperm in the ejaculate is due to a physical blockage in the ductal system (e.g., vas deferens, epididymis). * Since the Sertoli cells are functioning normally, they produce **Inhibin B**, which keeps **FSH** levels within the normal range via negative feedback. * Since the Leydig cells are unaffected, testosterone production is normal, maintaining **LH** levels within the normal range. ### **Analysis of Incorrect Options** * **Option A, C, & D:** These patterns represent **Non-obstructive Azoospermia** (Primary Testicular Failure). When the testes fail to produce sperm or testosterone, the lack of negative feedback (low Inhibin B and low Testosterone) causes the pituitary to secrete compensatory high levels of FSH and LH. Specifically, an isolated **raised FSH** is the most sensitive marker of impaired spermatogenesis. ### **High-Yield Clinical Pearls for NEET-PG** * **Most common cause of Obstructive Azoospermia:** Congenital Bilateral Absence of Vas Deferens (CBAVD), often associated with **CFTR gene mutations** (Cystic Fibrosis). * **Diagnostic Marker:** In obstructive cases, the **testicular size** is usually normal, whereas in non-obstructive cases, the testes are often small and soft. * **Fructose Test:** If the obstruction is at the level of the ejaculatory ducts or there is seminal vesicle agenesis, the semen analysis will show **low volume, acidic pH, and absent fructose**.

Q: Which of the following parameters is NOT increased during pregnancy?

Vital capacity. **Explanation:** In pregnancy, significant physiological adaptations occur to meet the metabolic demands of the fetus. However, **Vital Capacity (VC)** remains **unchanged** or may show a negligible increase. While the growing uterus elevates the diaphragm by approximately 4 cm, there is a compensatory increase in the transverse and anteroposterior diameters of the thoracic cage due to the relaxation of ligamentous attachments (mediated by the hormone Relaxin). This ensures that the total volume of air that can be forcibly exhaled after a maximum inhalation remains stable. **Analysis of Options:** * **B. Blood Volume:** Increases significantly (up to 40–50%) to support placental perfusion. Plasma volume increases more than red cell mass, leading to "physiological anemia of pregnancy." * **C. Extracellular Fluid (ECF):** There is a marked increase in ECF due to sodium and water retention (mediated by the RAAS pathway and estrogen), contributing to the physiological edema often seen in the lower limbs. * **D. Weight:** An average weight gain of 11–12 kg is expected, attributed to the fetus, placenta, amniotic fluid, increased uterine/breast size, and expanded fluid volumes. **High-Yield NEET-PG Pearls:** * **Tidal Volume (TV):** Increases by ~40% (the most significant change in respiratory parameters). * **Functional Residual Capacity (FRC):** Decreases by ~20% due to the elevation of the diaphragm. * **Respiratory Rate:** Remains largely **unchanged**, but Minute Ventilation increases due to the rise in TV. * **State of Ventilation:** Pregnancy is a state of **chronic mild hyperventilation**, leading to respiratory alkalosis with renal compensation (decreased $PCO_2$).

Q: Inhibin is secreted by which of the following cells?

Granulosa cell. **Explanation:** **Inhibin** is a glycoprotein hormone that plays a critical role in the negative feedback regulation of the hypothalamic-pituitary-gonadal axis. Its primary function is the **selective inhibition of Follicle-Stimulating Hormone (FSH)** secretion from the anterior pituitary. 1. **Why Granulosa Cells are correct:** In females, Inhibin (specifically Inhibin B) is synthesized and secreted by the **Granulosa cells** of the developing ovarian follicles. As the follicle grows under the influence of FSH, these cells produce more Inhibin, which then feeds back to the pituitary to suppress FSH, preventing the over-stimulation of multiple follicles. (Note: In males, the functional equivalent is the **Sertoli cell**). 2. **Why other options are incorrect:** * **Theca cells:** These cells primarily produce androgens (androstenedione) under the influence of LH, which are then converted to estrogens by granulosa cells. * **Corpus luteum:** While the corpus luteum does secrete **Inhibin A** (along with progesterone and estrogen) during the luteal phase, the classic and primary source of Inhibin in the follicular phase and the most common answer for this physiological concept is the Granulosa cell. * **Decidua:** This is the modified mucosal lining of the uterus during pregnancy; it is involved in maternal-fetal exchange and hormone production (like prolactin), but not the primary secretion of Inhibin. **High-Yield Clinical Pearls for NEET-PG:** * **Inhibin B:** Marker of **ovarian reserve**; produced by small antral follicles. * **Inhibin A:** Produced by the **dominant follicle** and the **Corpus Luteum**. * **Tumor Marker:** Inhibin is a highly specific tumor marker for **Granulosa Cell Tumors** of the ovary. * **Dual Action:** While Inhibin suppresses FSH, **Activin** (also from granulosa cells) stimulates FSH secretion.

Q: A young woman enters puberty with approximately 40,000 primary oocytes in her ovary. About how many of these primary oocytes will be ovulated over the entire reproductive life of the woman?

480. **Explanation:** The correct answer is **480 (Option C)**. This calculation is based on the duration of a woman's reproductive lifespan and the physiology of the menstrual cycle. **1. Why the Correct Answer is Right:** A woman’s reproductive life typically spans from **menarche** (onset of menstruation, ~12 years) to **menopause** (cessation of menstruation, ~52 years), lasting approximately **40 years**. * **Calculation:** 40 years × 12 months/year = **480 cycles**. * Since usually only one dominant follicle matures and releases an oocyte (ovulation) per cycle, roughly 400 to 500 oocytes are ovulated in a lifetime. The remaining 99.9% of the oocytes present at puberty undergo a degenerative process called **atresia**. **2. Why Incorrect Options are Wrong:** * **Options A & B (40,000 and 35,000):** These numbers represent the pool of available oocytes at puberty, not the number ovulated. Most oocytes are "wasted" through atresia regardless of whether a woman is pregnant, on oral contraceptives, or anovulatory. * **Option D (48):** This is mathematically too low, representing only about 4 years of reproductive life. **3. High-Yield NEET-PG Clinical Pearls:** * **Oocyte Count Timeline:** * **Peak:** 7 million at 20 weeks of gestation (fetal life). * **At Birth:** 1–2 million. * **At Puberty:** 300,000 to 400,000 (though the question uses 40,000 as a specific premise, the logic remains the same). * **Meiotic Arrest:** Primary oocytes are arrested in the **Prophase of Meiosis I (Dictyotene stage)** until ovulation. Secondary oocytes are arrested in **Metaphase of Meiosis II** until fertilization. * **Atresia:** This is an apoptotic process that is independent of FSH/LH levels during prepubertal years but becomes regulated by gonadotropins after puberty.

Q: What is the primary source of human chorionic gonadotropin (HCG)?

Syncytiotrophoblast. **Explanation:** The primary source of **Human Chorionic Gonadotropin (hCG)** is the **Syncytiotrophoblast**, the outer, multinucleated layer of the trophoblast that invades the uterine wall. 1. **Why Syncytiotrophoblast is correct:** Shortly after implantation (around day 8 post-fertilization), the syncytiotrophoblast begins secreting hCG. This hormone is crucial for maintaining the **corpus luteum**, ensuring the continued secretion of progesterone to support the pregnancy until the placenta takes over steroidogenesis (the luteal-placental shift). 2. **Why other options are incorrect:** * **Cytotrophoblast:** This is the inner, single-cell layer of the trophoblast. While it acts as a precursor to the syncytiotrophoblast, its primary endocrine product is **CRH (Corticotropin-Releasing Hormone)** and GnRH, not hCG. * **Langhan’s layer:** This is simply another name for the **Cytotrophoblast**. These cells are prominent in early pregnancy but thin out as gestation progresses. * **Chorionic villi:** While the villi as a whole produce hormones, the term refers to the entire structural unit (comprising the syncytium, cytotrophoblast, and mesoderm). The specific cellular source within the villi is the syncytiotrophoblast. **High-Yield Clinical Pearls for NEET-PG:** * **Doubling Time:** In early pregnancy, hCG levels double every **48–72 hours**. * **Peak Levels:** hCG levels peak at **8–10 weeks** of gestation and then decline to a lower plateau. * **Structure:** hCG is a glycoprotein with two subunits. The **$\alpha$-subunit** is identical to LH, FSH, and TSH; the **$\beta$-subunit** is unique and is what pregnancy tests detect. * **Clinical Marker:** Pathologically high levels are seen in **Hydatidiform mole** and **Choriocarcinoma**, while low levels for gestational age may indicate an ectopic pregnancy or impending abortion.

Q: During intrauterine life, which of the following organs is not dependent upon the placenta?

Lung. Explanation: In fetal life, the **placenta** serves as the primary organ for gas exchange, nutrient uptake, and waste elimination [1]. The correct answer is the **Lung** because, during intrauterine development, the lungs are non-functional for respiration [3]. They are filled with fluid, and the pulmonary vascular resistance is high, shunting most blood away from the lungs via the ductus arteriosus [4]. Oxygenation occurs entirely at the placenta; therefore, the fetus does not depend on the lungs for survival in utero. Analysis of Options: * **Liver (Incorrect):** While the placenta performs many metabolic functions, the fetal liver is vital for hematopoiesis (starting at 6 weeks) and the synthesis of coagulation factors and albumin. It receives the highest concentration of oxygenated blood via the umbilical vein [2]. * **Kidney (Incorrect):** Although the placenta handles waste excretion, the fetal kidneys are essential for producing **amniotic fluid** (starting around week 10-12). Renal agenesis leads to oligohydramnios and Potter sequence, proving the fetus's dependence on renal function for normal development. * **Brain (Incorrect):** The fetal brain is highly dependent on the placenta for a continuous supply of glucose and oxygen. The fetal circulation is specifically designed (via the foramen ovale) to shunt the most oxygenated blood toward the carotid arteries to support rapid cephalic development [4]. High-Yield Clinical Pearls for NEET-PG: * **Fetal Circulation:** The **Umbilical Vein** carries the most oxygenated blood ($SaO_2 \approx 80\%$), while the **Umbilical Arteries** carry the least [2]. * **First Breath:** At birth, the expansion of the lungs decreases pulmonary vascular resistance, leading to the closure of fetal shunts (Ductus Arteriosus, Foramen Ovale). * **Amniotic Fluid:** In the second half of pregnancy, fetal urine is the major contributor to amniotic fluid volume.

Q: From where does a growing fetus derive its energy?

Carbohydrates. **Explanation:** The primary and preferred source of energy for a growing fetus is **Carbohydrates**, specifically **Glucose**. Glucose is the only major nutrient that crosses the placenta via **facilitated diffusion** (through GLUT-1 and GLUT-3 transporters) in significant quantities to meet the high metabolic demands of the developing brain and tissues. While the fetus can synthesize its own glycogen and fat, it depends almost entirely on the maternal glucose supply for its immediate oxidative metabolism. **Why other options are incorrect:** * **Amino acids:** While amino acids are actively transported across the placenta, they are primarily used as building blocks for **protein synthesis** and tissue growth rather than as a primary energy source. * **Lipids:** Free fatty acids cross the placenta in limited amounts. While they are essential for brain development (DHA/EPA) and the formation of cell membranes, the fetus has a limited capacity for beta-oxidation, making lipids a secondary energy source compared to glucose. * **Minerals:** Minerals (like Calcium and Iron) are essential cofactors for enzymatic reactions and structural development (bone mineralization) but do not provide caloric energy. **NEET-PG High-Yield Pearls:** * **GLUT-1** is the primary glucose transporter in the human placenta. * **Fetal Insulin:** The fetus secretes its own insulin starting from the end of the first trimester; maternal insulin does **not** cross the placenta. * **Warburg-like Effect:** Fetal tissues often exhibit high rates of glycolysis even in the presence of oxygen to support rapid biosynthesis. * **Ketone Bodies:** These can cross the placenta and serve as an alternative fuel source only during periods of maternal starvation or prolonged fasting.

Q: What stimulates prolactin production, which in turn stimulates breast milk production?

Progesterone levels decrease following placental delivery.. **Explanation:** The correct answer is **B. Progesterone levels decrease following placental delivery.** **Mechanism:** During pregnancy, high levels of **estrogen and progesterone** (primarily from the placenta) stimulate breast ductal and alveolar development. However, these same hormones—specifically progesterone—exert a potent inhibitory effect on the anterior pituitary’s response to prolactin. They essentially "block" prolactin from initiating milk synthesis. Upon delivery of the placenta, the sudden withdrawal of progesterone removes this inhibition. This "progesterone withdrawal" allows prolactin to act unopposed on the mammary glands, triggering **lactogenesis II** (the onset of copious milk secretion). **Analysis of Incorrect Options:** * **Option A:** Acinar cells produce colostrum (Lactogenesis I) during the late stages of pregnancy, but this occurs *before* the massive surge in mature milk production triggered by prolactin post-delivery. * **Option C:** The letdown reflex (milk ejection) is mediated by **Oxytocin** in response to suckling. While it is essential for milk delivery, it does not stimulate the *production* of milk; that is the role of prolactin. * **Option D:** Progesterone levels do not increase after delivery; they plummet because the primary source (the placenta) has been removed. **NEET-PG High-Yield Pearls:** * **Prolactin:** Produced by lactotrophs in the anterior pituitary; responsible for milk **production** (synthesis). * **Oxytocin:** Produced in the hypothalamus (stored in the posterior pituitary); responsible for milk **ejection** (letdown). * **Prolactin Inhibitory Factor (PIF):** This is actually **Dopamine**. Drugs that antagonize dopamine (e.g., Metoclopramide) can cause galactorrhea. * **Suckling Reflex:** Suckling inhibits dopamine release, thereby increasing prolactin levels to ensure continued milk production.

Question 1

Which of the following is true about obstructive azoospermia?

Accepted Answer

Normal FSH and normal LH

Answer

FSH and LH are increased

Answer

LH is raised and FSH is normal

Answer

FSH is raised and LH is normal

Question 2

Which of the following parameters is NOT increased during pregnancy?

Accepted Answer

Vital capacity

Answer

Blood volume

Answer

Extracellular fluid

Answer

Weight

Question 3

Inhibin is secreted by which of the following cells?

Accepted Answer

Granulosa cell

Answer

Theca cell

Answer

Corpus luteum

Answer

Decidua

Question 4

A young woman enters puberty with approximately 40,000 primary oocytes in her ovary. About how many of these primary oocytes will be ovulated over the entire reproductive life of the woman?

Accepted Answer

480

Answer

40,000

Answer

35,000

Answer

48

Question 5

In evaluating the menstrual cycle, which statement is true?

Accepted Answer

Ovulation follows a surge in LH.

Answer

Estrogen secretion predominates during the week prior to menstruation.

Answer

Progesterone predominates the first week after menstruation.

Answer

FSH is released at midcycle.

Question 6

What is the primary source of human chorionic gonadotropin (HCG)?

Accepted Answer

Syncytiotrophoblast

Answer

Cytotrophoblast

Answer

Langhan's layer

Answer

Chorionic villi

Question 7

Which of the following is NOT related to granulosa cells?

Accepted Answer

In the first half of the cycle, it has no steroidogenic function

Answer

It has no blood supply

Answer

Granulosa cells produce activin and inhibin

Answer

Estrogen stimulates the proliferation of granulosa cells

Question 8

During intrauterine life, which of the following organs is not dependent upon the placenta?

Accepted Answer

Lung

Answer

Liver

Answer

Kidney

Answer

Brain

Question 9

From where does a growing fetus derive its energy?

Accepted Answer

Carbohydrates

Answer

Amino acids

Answer

Lipids

Answer

Minerals

Question 10

What stimulates prolactin production, which in turn stimulates breast milk production?

Accepted Answer

Progesterone levels decrease following placental delivery.

Answer

Acinar cells begin producing colostrum.

Answer

The letdown reflex occurs.

Answer

Progesterone levels increase following placental delivery.

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

On this page

Practice by Chapter

Want unlimited practice?