Reproductive Physiology — MCQs
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What accompanies sloughing of the endometrium during the menstrual cycle in a normal woman?
The primary reason that the female phenotype develops in an XY male is:
Ovarian follicles produce increased amounts of Estrogen and inhibin during which phase?
What is the average blood loss during normal menstruation?
Post ovulation, what is the characteristic of the cervical mucus?
Sperm are released during ejaculation from which structure?
Androgen binding protein is secreted by which cells?
Which hormone is responsible for lactation?
Which of the following are physiological changes of pregnancy?
Ovulation in a female with a 38-day cycle occurs on which day?
Reproductive Physiology Indian Medical PG Practice Questions and MCQs
Question 81: What accompanies sloughing of the endometrium during the menstrual cycle in a normal woman?
- A. An increase in progesterone
- B. The luteinizing hormone (LH) surge
- C. A decrease in both progesterone and estrogen (Correct Answer)
- D. An increase in estradiol
Explanation: **Explanation:** The menstrual cycle is governed by the rhythmic fluctuation of ovarian hormones. Menstruation (sloughing of the endometrium) occurs at the end of the luteal phase due to the **involution of the corpus luteum**. **Why the correct answer is right:** In a non-pregnant cycle, the corpus luteum degenerates approximately 14 days after ovulation. Since the corpus luteum is the primary source of **progesterone and estrogen** during the secretory phase, its regression leads to a precipitous drop in these hormones. This withdrawal causes: 1. Spasms of the spiral arteries. 2. Endometrial ischemia and necrosis. 3. Release of lysosomal enzymes, leading to the shedding of the *stratum functionalis*. **Analysis of Incorrect Options:** * **Option A & D:** An increase in progesterone or estradiol (estrogen) would stabilize the endometrium. Progesterone is known as the "hormone of pregnancy" because it maintains the endometrial lining; its withdrawal is the specific trigger for menstruation. * **Option B:** The **LH surge** occurs mid-cycle (approximately 24–36 hours before ovulation). It triggers the release of the oocyte, not the shedding of the lining. **NEET-PG High-Yield Pearls:** * **Day 1** of the cycle is defined as the first day of menstrual bleeding. * **Progesterone withdrawal** is the most critical factor for the initiation of menstruation. * The **Luteal Phase** is constant (14 days), whereas the Follicular Phase varies in length. * **Spiral arteries** are the specific vessels that undergo vasoconstriction leading to endometrial sloughing.
Question 82: The primary reason that the female phenotype develops in an XY male is:
- A. The secretion of progesterone
- B. Adrenal insufficiency
- C. The lack of testosterone action (Correct Answer)
- D. Increased inhibin secretion
Explanation: ### Explanation The default pathway of sexual differentiation in humans is **female**. For a male phenotype to develop, specific active signals are required from the Y chromosome. **1. Why "Lack of testosterone action" is correct:** In an XY individual, the *SRY* gene on the Y chromosome triggers the bipotential gonads to develop into testes. The testes then secrete two critical hormones: * **Müllerian Inhibiting Substance (MIS/AMH):** Causes regression of the paramesonephric (Müllerian) ducts (internal female structures). * **Testosterone:** Stimulates the development of Wolffian ducts into internal male structures and, via conversion to Dihydrotestosterone (DHT), promotes external male genitalia. If there is a **lack of testosterone action** (e.g., **Androgen Insensitivity Syndrome**), the body cannot respond to male hormones. Despite having testes and MIS (which prevents internal female organs), the external genitalia default to the female phenotype. **2. Why the other options are incorrect:** * **A & D:** Progesterone and Inhibin do not play a primary role in sex determination or the differentiation of external genitalia. * **B:** Adrenal insufficiency (like Addison’s) affects salt/water balance and cortisol but does not cause a female phenotype in an XY male. Conversely, Congenital Adrenal Hyperplasia (CAH) causes *virilization* in XX females, not feminization in XY males. **3. Clinical Pearls for NEET-PG:** * **Androgen Insensitivity Syndrome (AIS):** Genotype 46,XY; Phenotype Female. Key features: Blind-ending vagina, absent uterus (due to MIS), and undescended testes (often presenting as inguinal hernias). * **Swyer Syndrome:** 46,XY with *SRY* mutation; results in streak gonads and presence of a uterus (because no MIS is produced). * **Müllerian Duct:** Forms Fallopian tubes, Uterus, and upper 1/3 of the Vagina. * **Wolffian Duct:** Forms Epididymis, Vas deferens, and Seminal vesicles (**SEED**: Seminal vesicle, Epididymis, Ejaculatory duct, Ductous deferens).
Question 83: Ovarian follicles produce increased amounts of Estrogen and inhibin during which phase?
- A. Early follicular phase
- B. Mid follicular phase (Correct Answer)
- C. Late follicular phase
- D. Early luteal phase
Explanation: **Explanation:** The correct answer is **Mid follicular phase**. This phase is characterized by the selection and growth of the dominant follicle, which becomes the primary source of ovarian hormones. 1. **Why Mid follicular phase is correct:** During this stage (roughly days 7–10), the granulosa cells of the developing follicles (under the influence of FSH) significantly increase the expression of the enzyme **aromatase**. This leads to a surge in **Estrogen** production. Simultaneously, these granulosa cells secrete **Inhibin B**. The rising levels of both Estrogen and Inhibin B exert negative feedback on the anterior pituitary to decrease FSH secretion, a crucial step in selecting the dominant follicle while others undergo atresia. 2. **Why other options are incorrect:** * **Early follicular phase:** Hormone levels are at their lowest as the corpus luteum has just regressed. FSH is just beginning to rise to recruit a new cohort of follicles. * **Late follicular phase:** While Estrogen peaks here, it triggers the LH surge. Inhibin levels remain high, but the "increase" and the critical feedback mechanism that defines the follicular dynamics are established in the mid-phase. * **Early luteal phase:** This phase is dominated by the corpus luteum, which produces high amounts of **Progesterone** and **Inhibin A**, rather than the follicular production of Estrogen and Inhibin B. **High-Yield NEET-PG Pearls:** * **Inhibin B** is the marker of the follicular phase (produced by granulosa cells). * **Inhibin A** is the marker of the luteal phase (produced by the corpus luteum). * **Estrogen Feedback:** Low/Moderate Estrogen (Mid-follicular) = Negative feedback on FSH/LH. High Estrogen for >48 hours (Late-follicular) = Positive feedback leading to the LH surge.
Question 84: What is the average blood loss during normal menstruation?
- A. 50 ml (Correct Answer)
- B. 80 ml
- C. 100 ml
- D. 120 ml
Explanation: **Explanation:** The average blood loss during a normal menstrual cycle is approximately **35 to 50 ml**. While the range can vary between 10 ml and 80 ml, 50 ml is considered the standard physiological mean in most medical textbooks (including Ganong and Guyton). * **Option A (50 ml):** This is the correct average. Menstrual fluid consists of roughly 50% blood and 50% serous fluid, cervical mucus, and endometrial debris. * **Option B (80 ml):** This is the **upper limit** of normal. Blood loss exceeding 80 ml per cycle is clinically defined as **Menorrhagia** (Heavy Menstrual Bleeding), which often leads to iron deficiency anemia. * **Options C & D (100 ml and 120 ml):** These values are well above the physiological average and are considered pathological, indicating underlying conditions such as fibroids, adenomyosis, or coagulopathies. **High-Yield Clinical Pearls for NEET-PG:** 1. **Duration:** Normal menstruation lasts 3–7 days; the cycle length is typically 28 ± 7 days. 2. **Clotting:** Normal menstrual blood **does not clot** because of the presence of **plasmin** (fibrinolysin) released from the endometrial tissue. The presence of large clots usually indicates excessive bleeding (menorrhagia). 3. **Hormonal Trigger:** Menstruation is primarily caused by the sudden **withdrawal of Progesterone** (and Estrogen) following the involution of the Corpus Luteum. 4. **Iron Loss:** An average loss of 50 ml of blood results in the loss of approximately 0.5 to 1.0 mg of iron per day over the cycle.
Question 85: Post ovulation, what is the characteristic of the cervical mucus?
- A. Shows ferning pattern on drying
- B. Is thick and less permeable (Correct Answer)
- C. Is thin and cellular
- D. Is thin and alkaline
Explanation: **Explanation:** The characteristics of cervical mucus are primarily governed by the cyclical changes in ovarian hormones—**Estrogen** and **Progesterone**. **1. Why the correct answer is right:** Post-ovulation, the **Luteal Phase** begins, dominated by **Progesterone** secreted by the corpus luteum. Progesterone acts on the cervical glands to produce mucus that is **thick, viscid, and cellular**. This change serves a physiological purpose: it creates a "mucus plug" that is **less permeable** to sperm, effectively closing the cervix to further sperm penetration once fertilization has likely occurred or the fertile window has passed. **2. Analysis of Incorrect Options:** * **Option A (Ferning pattern):** Ferning occurs due to high sodium chloride content under the influence of **Estrogen** (pre-ovulatory phase). Progesterone inhibits this, leading to a "non-ferning" or granular pattern post-ovulation. * **Option C & D (Thin and alkaline):** These are features of the **Pre-ovulatory (Follicular) phase**. High estrogen levels make the mucus thin, watery, alkaline, and rich in mucin, which facilitates sperm transport. **3. High-Yield Clinical Pearls for NEET-PG:** * **Spinnbarkeit Phenomenon:** Refers to the "stretchability" of cervical mucus. It is maximum (10–12 cm) just before ovulation (Estrogen effect) and disappears post-ovulation (Progesterone effect). * **Billings Method:** A natural family planning method where a woman monitors these mucus changes to identify her fertile window. * **Cervical Score (Insler Score):** Used to assess ovulation; a high score indicates thin, clear, stretchy mucus (Estrogen dominance), while a low score indicates thick, opaque mucus (Progesterone dominance).
Question 86: Sperm are released during ejaculation from which structure?
- A. Seminal vesicles
- B. Epididymis (Correct Answer)
- C. Testes
- D. Prostate
Explanation: **Explanation:** The correct answer is **Epididymis**. While sperm are produced in the testes, they are stored and undergo functional maturation in the epididymis. During the process of emission and ejaculation, forceful sympathetic contractions of the smooth muscles in the **tail (cauda) of the epididymis** and the vas deferens propel the stored sperm into the ejaculatory ducts. **Analysis of Options:** * **Seminal Vesicles (A):** These glands do not store sperm. They contribute approximately 60-70% of the total ejaculate volume, providing fructose (energy source), prostaglandins, and fibrinogen. * **Testes (C):** The testes are the site of **spermatogenesis** (production) within the seminiferous tubules. However, sperm here are immotile and are transported to the epididymis via the efferent ductules; they are not directly released from the testes during ejaculation. * **Prostate (D):** The prostate gland secretes a thin, milky, alkaline fluid (about 20-30% of ejaculate) that neutralizes vaginal acidity and contains clotting enzymes and fibrinolysin. It does not store or release sperm. **NEET-PG High-Yield Pearls:** * **Sperm Maturation:** Sperm acquire motility and the ability to fertilize (decapacitation factors) specifically in the epididymis. * **Storage:** The majority of sperm are stored in the **cauda (tail) epididymis** and the proximal vas deferens, where they can remain viable for several weeks. * **Ejaculation Pathway:** Epididymis → Vas deferens → Ejaculatory duct → Prostatic urethra → Penile urethra. * **Fructose Test:** Since fructose is only produced by seminal vesicles, its absence in semen (azoospermia) suggests a blockage or congenital absence of the vas deferens/seminal vesicles.
Question 87: Androgen binding protein is secreted by which cells?
- A. Pituitary
- B. Liver
- C. Sertoli cells (Correct Answer)
- D. Leydig cells
Explanation: **Explanation:** **1. Why Sertoli cells are correct:** Androgen Binding Protein (ABP) is a glycoprotein synthesized and secreted by the **Sertoli cells** of the testes. Its primary function is to bind to testosterone, dihydrotestosterone (DHT), and 17β-estradiol. By binding testosterone, ABP ensures that the local concentration of this hormone remains high within the seminiferous tubules (up to 100 times higher than in systemic circulation). This high concentration is absolutely essential for the process of **spermatogenesis**. The production of ABP by Sertoli cells is stimulated by **Follicle-Stimulating Hormone (FSH)**. **2. Why the other options are incorrect:** * **Pituitary:** The anterior pituitary secretes gonadotropins (FSH and LH) which regulate the testes, but it does not produce ABP. * **Liver:** The liver produces **Sex Hormone-Binding Globulin (SHBG)**. While SHBG is chemically similar to ABP, it functions to transport steroids in the systemic blood, whereas ABP acts locally in the male reproductive tract. * **Leydig cells:** These cells are located in the interstitium and are responsible for the synthesis of **Testosterone** under the influence of Luteinizing Hormone (LH). They do not secrete ABP. **3. High-Yield Facts for NEET-PG:** * **Blood-Testis Barrier:** Formed by tight junctions between Sertoli cells; ABP helps maintain the chemical environment within this barrier. * **Inhibin B:** Also secreted by Sertoli cells, it provides negative feedback to the anterior pituitary to inhibit FSH. * **Blood-Testis Marker:** ABP can be used as a marker of Sertoli cell function. * **Mnemonic:** **S**ertoli cells **S**upport **S**permatogenesis and secrete **S**ubstances like ABP and Inhibin.
Question 88: Which hormone is responsible for lactation?
- A. Prolactin (Correct Answer)
- B. FSH
- C. LH
- D. Progesterone
Explanation: **Explanation:** **Prolactin (Option A)** is the correct answer because it is the primary hormone responsible for the **production (synthesis) of milk** within the mammary glands. Produced by the lactotrophs of the anterior pituitary, prolactin levels rise significantly during pregnancy, but its effect is inhibited by high levels of estrogen and progesterone. Post-delivery, the sudden drop in these steroid hormones allows prolactin to initiate and maintain milk secretion (lactogenesis). **Why other options are incorrect:** * **FSH (Follicle Stimulating Hormone) & LH (Luteinizing Hormone):** These are gonadotropins responsible for follicular development and ovulation, respectively. During lactation, high prolactin levels actually inhibit the release of GnRH, leading to "lactational amenorrhea." * **Progesterone:** While it promotes the development of the alveoli in the breast during pregnancy, it is a potent **inhibitor** of milk production. Lactation only begins once progesterone levels fall after the expulsion of the placenta. **NEET-PG High-Yield Pearls:** 1. **Production vs. Ejection:** Prolactin is for milk **production** (Anterior Pituitary), whereas Oxytocin is for milk **ejection/let-down reflex** (Posterior Pituitary). 2. **Regulation:** Prolactin is the only anterior pituitary hormone under tonic **inhibition** by Dopamine (Prolactin Inhibiting Hormone). 3. **Suckling Stimulus:** The strongest stimulus for prolactin release is suckling, which inhibits dopamine release in the hypothalamus. 4. **Clinical Correlation:** Hyperprolactinemia (e.g., due to a Prolactinoma) causes galactorrhea and infertility.
Question 89: Which of the following are physiological changes of pregnancy?
- A. Insulin levels increase and increased Basal Metabolic Rate (BMR) (Correct Answer)
- B. Insulin levels increase and hypothyroidism
- C. Increased Basal Metabolic Rate (BMR) and hypothyroidism
- D. Growth Hormone (GH) decreases and increased Basal Metabolic Rate (BMR)
Explanation: **Explanation:** Pregnancy is a state of significant metabolic and endocrine adaptation to support fetal growth and development. **1. Why Option A is Correct:** * **Insulin Levels:** Pregnancy is characterized by **progressive insulin resistance** (primarily due to Human Placental Lactogen, Progesterone, and Cortisol). To compensate and maintain euglycemia, the maternal pancreas undergoes beta-cell hyperplasia, leading to **increased fasting and postprandial insulin levels**. * **Basal Metabolic Rate (BMR):** The BMR increases significantly (by approximately **15–20%**) during pregnancy. This is driven by the increased oxygen demands of the growing fetus, the placenta, and the expansion of maternal cardiac and respiratory workloads. **2. Why Other Options are Incorrect:** * **Hypothyroidism (Options B & C):** Pregnancy is actually a **hyperthyroid-like state**, not hypothyroid. Estrogen increases Thyroid Binding Globulin (TBG), leading to higher total T3 and T4 levels. Additionally, hCG (which shares a sub-unit with TSH) weakly stimulates the thyroid gland. * **Growth Hormone (Option D):** While pituitary GH secretion decreases due to feedback inhibition, **Placental Growth Hormone** increases significantly, becoming the dominant GH variant in the maternal circulation by the second trimester. **High-Yield NEET-PG Pearls:** * **Diabetogenic State:** Pregnancy is often described as a "state of accelerated starvation" during fasting and "postprandial hyperglycemia" to ensure a continuous glucose supply to the fetus. * **Hematology:** Plasma volume increases (50%) more than Red Cell Mass (20-30%), leading to **physiological anemia**. * **Respiratory:** Progesterone acts as a respiratory stimulant, increasing tidal volume and causing a state of **chronic respiratory alkalosis** (compensated).
Question 90: Ovulation in a female with a 38-day cycle occurs on which day?
- A. 14th day
- B. 8th day
- C. 24th day (Correct Answer)
- D. 30th day
Explanation: **Explanation:** The key to solving this question lies in understanding the phases of the menstrual cycle. A menstrual cycle is divided into two main phases: the **Follicular (Proliferative) phase** and the **Luteal (Secretory) phase**. 1. **The Constant Luteal Phase:** In a healthy menstrual cycle, the duration of the luteal phase is remarkably constant, lasting **14 days**. This is because the lifespan of the corpus luteum is fixed unless pregnancy occurs. 2. **The Variable Follicular Phase:** The total length of the cycle varies between individuals primarily due to variations in the length of the follicular phase. 3. **Calculation:** To determine the day of ovulation, one must subtract the constant luteal phase (14 days) from the total cycle length. * *Calculation:* 38 days (Total Cycle) – 14 days (Luteal Phase) = **24th day**. **Analysis of Incorrect Options:** * **Option A (14th day):** This is only correct for a "textbook" 28-day cycle (28 – 14 = 14). It is a common misconception that ovulation always occurs on day 14. * **Option B (8th day):** This would occur in an abnormally short cycle of 22 days. * **Option D (30th day):** This would imply a luteal phase of only 8 days, which is clinically associated with "Luteal Phase Deficiency" and infertility. **NEET-PG High-Yield Pearls:** * **Ovulation Trigger:** The LH surge is the immediate trigger for ovulation, occurring approximately 24–36 hours before the egg is released. * **Mittelschmerz Sign:** Unilateral lower abdominal pain experienced by some women during ovulation due to peritoneal irritation by follicular fluid/blood. * **Spinnbarkeit Effect:** Under the influence of estrogen just before ovulation, cervical mucus becomes thin, stretchy, and clear (resembling egg white). * **Basal Body Temperature (BBT):** Progesterone causes a slight rise (0.5–1.0°F) in BBT *after* ovulation has occurred.
Practice by Chapter
Male Reproductive Physiology
Practice Questions
Spermatogenesis and Sperm Function
Practice Questions
Female Reproductive Physiology
Practice Questions
Menstrual Cycle
Practice Questions
Ovulation and Fertilization
Practice Questions
Physiology of Pregnancy
Practice Questions
Parturition
Practice Questions
Lactation
Practice Questions
Sexual Differentiation and Development
Practice Questions
Reproductive Aging
Practice Questions
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