Reproductive Physiology Practice Questions

Q: Breastfeeding often stimulates which of the following?

Prolactin initiation. **Explanation:** The act of breastfeeding (suckling) triggers a neuroendocrine reflex known as the **Suckling Reflex**. When an infant suckles, sensory impulses travel from the nipple to the hypothalamus. This results in two primary actions: the inhibition of Dopamine (Prolactin Inhibiting Factor) and the stimulation of Prolactin release from the anterior pituitary. **Prolactin** is the primary hormone responsible for the **initiation and maintenance of milk production** (lactogenesis). **Analysis of Options:** * **Option C (Correct):** Suckling is the strongest physiological stimulus for prolactin secretion. It ensures a continuous supply of milk for the next feed. * **Options A & B (Incorrect):** Breastfeeding does not stimulate FSH or LH. In fact, high levels of Prolactin exert a negative feedback effect on the hypothalamus, inhibiting the pulsatile release of **GnRH** (Gonadotropin-Releasing Hormone). * **Option D (Incorrect):** While breastfeeding does lead to the suppression of FSH and LH (leading to lactational amenorrhea), the *primary* and most direct stimulatory effect of the suckling reflex is the initiation of Prolactin and Oxytocin. Between "initiation" and "suppression," the physiological "stimulation" specifically refers to the hormone being released. **NEET-PG High-Yield Pearls:** * **Prolactin:** Responsible for milk **production** (Anterior Pituitary). * **Oxytocin:** Responsible for milk **ejection** (Milk let-down reflex; Posterior Pituitary). * **Lactational Amenorrhea:** Elevated prolactin inhibits GnRH, which suppresses the LH surge, acting as a natural (but not 100% reliable) form of contraception. * **Dopamine Antagonists:** Drugs like Metoclopramide can increase prolactin levels (galactorrhea) because they block the inhibitory effect of dopamine.

Q: What is the major estrogen in normal adult women?

Estradiol. **Explanation:** In normal, non-pregnant adult women of reproductive age, **Estradiol (E2)** is the predominant and most potent circulating estrogen. It is primarily secreted by the granulosa cells of the ovarian follicles under the influence of FSH. Its potency is approximately 12 times that of estrone and 80 times that of estriol, making it the major driver of the female reproductive cycle and secondary sexual characteristics. **Analysis of Options:** * **Option A (Estradiol - E2):** Correct. It is the major estrogen during the reproductive years. * **Option B (Estrone - E1):** This is the predominant estrogen in **postmenopausal** women. It is weaker than estradiol and is primarily formed through the peripheral aromatization of androstenedione in adipose tissue. * **Option C (Estriol - E3):** This is the predominant estrogen during **pregnancy**. It is produced by the placenta using precursors (16-OH DHEAS) from the fetal liver and adrenal glands. It is the least potent of the three estrogens. * **Option D:** Incorrect, as Estradiol is the established major estrogen. **High-Yield NEET-PG Pearls:** 1. **Potency Order:** Estradiol (E2) > Estrone (E1) > Estriol (E3). (Mnemonic: **2 > 1 > 3**) 2. **Source:** The "Two-Cell, Two-Gonadotropin" theory explains its synthesis: LH stimulates Theca cells to produce androgens, which FSH then helps Granulosa cells convert into Estradiol via the enzyme **aromatase**. 3. **Clinical Marker:** Serum Estriol levels are used in the "Triple/Quadruple Screen" to monitor fetal well-being; low levels may indicate placental insufficiency or fetal anomalies.

Q: The karyotype in testicular feminising syndrome is?

XY. **Explanation:** **Testicular Feminization Syndrome**, now more commonly known as **Androgen Insensitivity Syndrome (AIS)**, is a condition where an individual is genetically male but phenotypically female. 1. **Why XY is Correct:** In AIS, the individual has a **46, XY karyotype**. The underlying pathology is a mutation in the **androgen receptor gene** (located on the X chromosome). Although the testes develop normally (due to the SRY gene) and secrete testosterone, the peripheral tissues cannot respond to it. Consequently, the external genitalia develop along female lines. However, because the testes still secrete **Müllerian Inhibiting Substance (MIS)**, internal female structures (uterus, fallopian tubes, upper vagina) are absent. 2. **Why Other Options are Incorrect:** * **XX:** This is a normal female karyotype. In cases of virilization (like Congenital Adrenal Hyperplasia), an XX individual may appear male, but this is the opposite of AIS. * **XXY:** This is the karyotype for **Klinefelter Syndrome**. These individuals have a male phenotype, small firm testes, and infertility, but they do not exhibit the complete feminization seen in AIS. * **XXXY:** This is a rare variant of Klinefelter Syndrome with more severe intellectual disability and physical abnormalities. **High-Yield Clinical Pearls for NEET-PG:** * **Phenotype:** Tall, attractive female with a "blind-ending vagina" and absent uterus. * **Pubic/Axillary Hair:** Characteristically **absent or scanty** (due to androgen resistance). * **Gonads:** Undescended testes are present (often in the inguinal canal or labia majora). These must be removed after puberty to prevent **gonadoblastoma/dysgerminoma**. * **Hormonal Profile:** High Testosterone, High LH, and normal to high Estrogen (via peripheral conversion).

Q: What is the increasing order of potency of estrogens (least potent to most potent)?

Estriol (E3), Estrone (E1), Estradiol (E2). **Explanation:** The potency of estrogens is determined by their affinity for estrogen receptors (ER-α and ER-β) and the duration of the receptor-hormone complex activation. 1. **Estradiol (E2):** The most potent and primary estrogen in non-pregnant females of reproductive age. It is produced mainly by the granulosa cells of the ovaries. 2. **Estrone (E1):** Possesses intermediate potency (about 1/10th of E2). It is the predominant estrogen post-menopause, derived primarily from the peripheral conversion of androstenedione in adipose tissue. 3. **Estriol (E3):** The least potent estrogen (about 1/100th of E2). It is produced in significant quantities only during pregnancy by the syncytiotrophoblast of the placenta. Therefore, the increasing order of potency is **Estriol (E3) < Estrone (E1) < Estradiol (E2)**. **Analysis of Incorrect Options:** * **Options A & B:** Incorrectly place Estrone or Estriol as more potent than Estradiol. * **Option D:** Incorrectly suggests Estradiol is the least potent, whereas it is the most biologically active form. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Potency:** **"E3 < E1 < E2"** (Count the syllables/numbers: 3 is the weakest, 2 is the strongest). * **Source of E3:** Estriol is a marker of fetal well-being; its synthesis requires the fetal liver and adrenal glands (DHEAS) and the placenta. * **PCOS Connection:** In Polycystic Ovary Syndrome, there is an increased **E1:E2 ratio** due to the peripheral conversion of androgens in adipose tissue. * **Menopause:** Estrone (E1) becomes the dominant circulating estrogen.

Q: A 26-year-old woman with a 32-day menstrual cycle, who is planning for conception, regularly checks her body temperature orally each morning before rising. She observes an increase in her body temperature on the 18th day of her menstrual cycle. What hormone causes this temperature increase?

Progesterone. **Explanation:** The correct answer is **Progesterone**. **Underlying Medical Concept:** In a normal menstrual cycle, the Basal Body Temperature (BBT) follows a biphasic pattern. During the follicular phase, temperatures are lower. Following ovulation, the ruptured follicle transforms into the **corpus luteum**, which secretes high levels of **progesterone**. Progesterone acts directly on the **hypothalamic thermoregulatory center**, increasing the set-point and causing a rise in body temperature by approximately 0.5°F to 1.0°F (0.3°C to 0.6°C). In this patient with a 32-day cycle, ovulation typically occurs around Day 18 (32 minus 14 days of the fixed luteal phase), correlating with the observed temperature spike. **Analysis of Incorrect Options:** * **A. Estradiol:** Estrogen levels peak just before ovulation. Estrogen actually has a mild "thermolyitc" (cooling) effect and is responsible for the lower temperatures seen in the follicular phase. * **C & D. LH and FSH Peaks:** These gonadotropins peak approximately 10–12 hours before ovulation. While they trigger the process that leads to the formation of the corpus luteum, they do not have a direct pyrogenic effect on the hypothalamus. **High-Yield Clinical Pearls for NEET-PG:** * **Fixed Luteal Phase:** Regardless of cycle length, the luteal phase is almost always constant at **14 days**. To calculate the day of ovulation, subtract 14 from the total cycle length. * **Thermogenic Effect:** Progesterone is the only hormone responsible for the biphasic BBT curve. This is a retrospective indicator that ovulation has occurred. * **Pregnancy Indicator:** If the BBT remains elevated for more than 18 consecutive days after the shift, it is a highly specific early sign of pregnancy.

Q: What hormone(s) does the corpus luteum secrete?

Both estrogens and progesterone. ### Explanation The **corpus luteum** is a temporary endocrine structure formed from the ovarian follicle after ovulation. Its primary function is to prepare the endometrium for potential implantation. **1. Why Option C is Correct:** After the LH (Luteinizing Hormone) surge triggers ovulation, the remaining granulosa and theca cells undergo **luteinization**. * **Granulosa lutein cells** primarily secrete large amounts of **progesterone**. * **Theca lutein cells** (and granulosa cells via aromatization) secrete **estrogen** (mainly estradiol). While progesterone is the dominant hormone of the luteal phase, the corpus luteum must secrete both to maintain the secretory endometrium. **2. Why Other Options are Incorrect:** * **Option A:** While the corpus luteum does secrete estrogen, selecting this alone ignores the massive production of progesterone, which is the hallmark of the luteal phase. * **Option B:** Progesterone is the "hormone of pregnancy," but the corpus luteum is not a single-hormone gland. It continues to produce estrogen to suppress further FSH release and support endometrial growth. **3. High-Yield Clinical Pearls for NEET-PG:** * **Life Span:** If fertilization does not occur, the corpus luteum degenerates into the **corpus albicans** after approximately 12–14 days due to a drop in LH. * **Rescue by hCG:** If pregnancy occurs, **hCG** (Human Chorionic Gonadotropin) from the syncytiotrophoblast "rescues" the corpus luteum, maintaining it for the first 8–10 weeks until the **luteal-placental shift** occurs. * **Inhibin A:** The corpus luteum also secretes **Inhibin A**, which further inhibits FSH secretion during the luteal phase. * **Relaxin:** It also produces relaxin, which helps in softening the cervix and relaxing pelvic ligaments during pregnancy.

Q: In the mother, suckling leads to which of the following responses?

Increase of hypothalamic prolactin. ### Explanation The act of suckling initiates a neuroendocrine reflex (the **Ferguson reflex** or milk-ejection reflex) that is crucial for lactation. **Why the correct answer is right:** When an infant suckles, tactile receptors on the nipple send afferent signals to the hypothalamus. This stimulus leads to a significant **increase in the synthesis and release of Prolactin** from the anterior pituitary. While the question mentions "hypothalamic prolactin," it refers to the hypothalamic-pituitary axis response where the hypothalamus suppresses its inhibitory control (dopamine), leading to a surge in prolactin levels to stimulate milk production in the mammary alveoli. **Analysis of Incorrect Options:** * **A. Decrease of oxytocin:** Incorrect. Suckling actually **increases** oxytocin release from the posterior pituitary. Oxytocin causes contraction of myoepithelial cells (milk let-down reflex). * **B. Increase of prolactin-inhibiting factor (PIF):** Incorrect. PIF is synonymous with Dopamine. Suckling **inhibits** the release of PIF/Dopamine to allow prolactin levels to rise. * **C. Increase of hypothalamic dopamine:** Incorrect. Dopamine acts as the primary inhibitor of prolactin. For lactation to occur, hypothalamic dopamine secretion must **decrease**. **NEET-PG High-Yield Pearls:** * **Prolactin vs. Oxytocin:** Prolactin is for milk **production** (Alveoli); Oxytocin is for milk **ejection** (Myoepithelial cells). * **Lactational Amenorrhea:** High prolactin levels during suckling inhibit **GnRH pulsatility**, leading to decreased LH/FSH and temporary infertility. * **Dopamine Antagonists:** Drugs like Metoclopramide can cause galactorrhea because they inhibit dopamine, thereby increasing prolactin.

Q: A young woman is given daily injections of a substance beginning on the sixteenth day of her normal menstrual cycle and continuing for 3 weeks. As long as the injections continue, she does not menstruate. The injected substance could be which of the following?

hCG. **Explanation:** The correct answer is **hCG (Human Chorionic Gonadotropin)**. **Why hCG is correct:** In a normal 28-day menstrual cycle, the corpus luteum begins to degenerate around day 24–26 due to a lack of luteotropic support, leading to a drop in progesterone and estrogen, which triggers menstruation. hCG is a glycoprotein hormone that is structurally and functionally similar to **LH (Luteinizing Hormone)**. When administered starting on day 16 (the early luteal phase), hCG "rescues" the corpus luteum, preventing its involution. This maintains high levels of progesterone and estrogen, which keeps the endometrium in the secretory phase and prevents menstruation. This mimics the physiological process of early pregnancy. **Why the other options are incorrect:** * **FSH:** Primarily functions to stimulate follicular development in the early follicular phase. It does not maintain the corpus luteum or prevent the withdrawal of progesterone. * **Inhibitor of progesterone’s actions:** Progesterone is essential for maintaining the endometrium. Inhibiting its action (e.g., Mifepristone) would induce menstruation or uterine bleeding, not prevent it. * **PGE2 inhibitor:** While prostaglandins are involved in uterine contractions and dysmenorrhea, inhibiting them does not prevent the hormonal withdrawal (progesterone drop) that causes the sloughing of the functional layer of the endometrium. **High-Yield NEET-PG Pearls:** * **Luteal Rescue:** hCG is the signal for "maternal recognition of pregnancy." * **Source:** hCG is secreted by the **syncytiotrophoblast**. * **Structure:** hCG shares a common **alpha subunit** with TSH, FSH, and LH; its specificity is determined by the **beta subunit**. * **Clinical Use:** hCG injections are used in clinical practice for ovulation induction and to support the luteal phase in infertility treatments.

Q: The phase of the ovarian cycle can be correlated with all of the following EXCEPT:

Estrous cycle. The ovarian cycle (comprising the follicular and luteal phases) is a physiological process specific to primates, including humans. The correct answer is **D. Estrous cycle**, as it is a distinct reproductive cycle found in non-primate mammals. ### Why "Estrous Cycle" is the Correct Answer: The **Estrous cycle** occurs in animals like dogs, cows, and rodents. Unlike the human menstrual cycle, where the endometrium is shed (menstruation), the endometrium in the estrous cycle is reabsorbed if fertilization does not occur. Furthermore, females are only sexually receptive during the "estrus" (heat) phase, whereas human females can be receptive throughout the cycle. Therefore, the ovarian cycle of a human cannot be correlated with an estrous cycle. ### Why the Other Options are Incorrect: * **A. Endometrial sampling:** The endometrium undergoes predictable changes (proliferative vs. secretory) in response to ovarian steroids (estrogen and progesterone). A biopsy can accurately date the phase of the ovarian cycle. * **B. Vaginal cytology:** The vaginal epithelium is sensitive to hormones. High estrogen (follicular phase) causes an increase in **superficial cells** (high Karyopyknotic Index), while progesterone (luteal phase) increases **intermediate cells**. * **C. Blood hormonal levels:** Measuring FSH, LH, Estradiol, and Progesterone provides a direct correlation. For example, high Progesterone (>3 ng/mL) definitively indicates the luteal phase (post-ovulation). ### NEET-PG High-Yield Pearls: * **Karyopyknotic Index (KI):** The percentage of superficial cells in a vaginal smear; it peaks at ovulation due to maximum estrogen. * **Fern Test:** Estrogen causes cervical mucus to "fern"; Progesterone (luteal phase) disappears this pattern. * **Spinnbarkeit Effect:** Maximum elasticity of cervical mucus occurs just before ovulation (follicular phase).

Question 1

Breastfeeding often stimulates which of the following?

Accepted Answer

Prolactin initiation

Answer

FSH

Answer

LH

Answer

Suppression of FSH

Question 2

What is the major estrogen in normal adult women?

Accepted Answer

Estradiol

Answer

Estrone

Answer

Estriol

Answer

None of the above

Question 3

The karyotype in testicular feminising syndrome is?

Accepted Answer

XY

Answer

XX

Answer

XXY

Answer

XXXY

Question 4

What is the increasing order of potency of estrogens (least potent to most potent)?

Accepted Answer

Estriol (E3), Estrone (E1), Estradiol (E2)

Answer

Estrone (E1), Estriol (E3), Estradiol (E2)

Answer

Estrone (E1), Estradiol (E2), Estriol (E3)

Answer

Estradiol (E2), Estrone (E1), Estriol (E3)

Question 5

A 26-year-old woman with a 32-day menstrual cycle, who is planning for conception, regularly checks her body temperature orally each morning before rising. She observes an increase in her body temperature on the 18th day of her menstrual cycle. What hormone causes this temperature increase?

Accepted Answer

Progesterone

Answer

Estradiol

Answer

LH peak

Answer

FSH peak

Question 6

What hormone(s) does the corpus luteum secrete?

Accepted Answer

Both estrogens and progesterone

Answer

Estrogens

Answer

Progesterone

Answer

None of the above

Question 7

In the mother, suckling leads to which of the following responses?

Accepted Answer

Increase of hypothalamic prolactin

Answer

Decrease of oxytocin

Answer

Increase of prolactin-inhibiting factor

Answer

Increase of hypothalamic dopamine

Question 8

A young woman is given daily injections of a substance beginning on the sixteenth day of her normal menstrual cycle and continuing for 3 weeks. As long as the injections continue, she does not menstruate. The injected substance could be which of the following?

Accepted Answer

hCG

Answer

FSH

Answer

An inhibitor of progesterone's actions

Answer

A PGE2 inhibitor

Question 9

Masculine or feminine features most directly depend on which of the following?

Accepted Answer

Serum testosterone levels

Answer

Amygdala

Answer

Genetic makeup

Answer

Hypothalamic outflow

Question 10

The phase of the ovarian cycle can be correlated with all of the following EXCEPT:

Accepted Answer

Estrous cycle

Answer

Endometrial sampling

Answer

Vaginal cytology

Answer

Blood hormonal levels

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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