Reproductive Physiology Practice Questions

Q: Stimulation of the nerves of the pelvic parasympathetic plexus results in:

Penile erection. ***Penile erection*** - The **pelvic splanchnic nerves** (parasympathetic) innervate the penile erectile tissues, leading to the release of **nitric oxide**. - **Nitric oxide** causes relaxation of smooth muscle in the arteries supplying the penis, leading to increased blood flow and engorgement of the cavernous spaces, resulting in erection. *Vasoconstriction* - **Vasoconstriction** is primarily mediated by the **sympathetic nervous system** through the release of norepinephrine, causing smooth muscle contraction in blood vessel walls. - The **parasympathetic nervous system** generally promotes vasodilation in specific organs like the penis, rather than widespread vasoconstriction. *Contraction of the genital smooth muscle* - While some genital smooth muscle contraction (e.g., during emission and ejaculation) involves the nervous system, **erection** specifically requires relaxation of vascular smooth muscle. - Contraction of the **bulbospongiosus** and **ischiocavernosus muscles** (skeletal muscles) helps maintain erection and contributes to ejaculation, but this is distinct from direct parasympathetic smooth muscle contraction needed for erection itself. *Constriction of the internal urethral sphincter* - **Constriction of the internal urethral sphincter** is mediated by the **sympathetic nervous system** during ejaculation to prevent retrograde ejaculation into the bladder. - The **parasympathetic nervous system** is primarily involved in bladder emptying (micturition) by relaxing the internal sphincter and contracting the detrusor muscle.

Q: During spermatogenesis, the number of chromosomes reduces to haploid at:

Meiosis-I. ***Meiosis-I*** - **Meiosis I** is known as the **reductional division** because it is during this stage that homologous chromosomes separate, leading to a reduction in the chromosome number from diploid (2n) to haploid (n) in each daughter cell. - This separation ensures that each secondary spermatocyte receives one chromosome from each homologous pair, thus having a **haploid set of chromosomes** (n chromosomes, each with two chromatids). *At mitosis* - **Mitosis** is a process of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, preserving the **diploid number (2n)**. - This process is used for growth and repair, not for reducing the chromosome number to haploid. *Meiosis-II* - **Meiosis II** is an **equational division**, meaning it separates the sister chromatids of the haploid cells formed during Meiosis I, similar to mitosis. - The chromosome number remains haploid (n) throughout Meiosis II; it does not further reduce the chromosome number. *None of the options* - This option is incorrect because **Meiosis-I** specifically serves the function of reducing the chromosome number to haploid during gamete formation.

Q: What hormones are secreted by the corpus luteum?

All of the options. ***All of the options*** - The **corpus luteum** is a temporary endocrine structure that forms from the ruptured follicle after ovulation. - It functions as an **endocrine gland** secreting multiple hormones essential for the luteal phase and early pregnancy. - The corpus luteum secretes **all three hormones listed**: progesterone, estrogen, and inhibin. **Hormonal Secretions of Corpus Luteum:** **Progesterone (Primary hormone)** - The corpus luteum is the **main source** of progesterone during the luteal phase. - Essential for **endometrial preparation** and maintenance of early pregnancy. - Prepares the endometrium for implantation and supports decidualization. **Estrogen (Secondary secretion)** - The corpus luteum continues to secrete **estrogen** in significant amounts during the luteal phase. - Works synergistically with progesterone to maintain the **endometrium**. - Lower levels than follicular phase but still physiologically important. **Inhibin (Regulatory hormone)** - The corpus luteum secretes **inhibin A** during the luteal phase. - Provides **negative feedback** to the anterior pituitary, suppressing FSH secretion. - Prevents recruitment of new follicles during the luteal phase. *Why individual options are incomplete:* - Selecting only "Progesterone," "Estrogen," or "Inhibin" would be factually correct but incomplete, as the question asks "What hormones" (plural), implying all hormones secreted should be identified.

Q: What physiological event occurs during ovulation?

FSH increases steroid synthesis in granulosa cells.. ***FSH increases steroid synthesis in granulosa cells.*** - During the **periovulatory period**, FSH continues to support **estrogen synthesis** in granulosa cells of the dominant follicle. - While FSH levels peak in the **mid-follicular phase**, FSH (along with the LH surge) maintains steroidogenic activity through ovulation. - Among the given options, this represents the most relevant ongoing physiological process during ovulation, though the primary event is follicular rupture and oocyte release. *Completion of the first meiotic division of the oocyte occurs just before ovulation.* - The **LH surge** triggers completion of **meiosis I** approximately **36-38 hours before ovulation**, forming a secondary oocyte and first polar body. - This event occurs **prior to** ovulation, not during it. At ovulation, the **secondary oocyte** (arrested in **metaphase II**) is released. - Meiosis II is only completed if **fertilization** occurs. *Inhibin A levels increase.* - **Inhibin A** levels rise significantly **after ovulation** during the **luteal phase**, produced by the corpus luteum. - Around ovulation, **inhibin B** is more prominent, while inhibin A remains relatively low. *Activin enhances FSH action on granulosa cells.* - **Activin** enhances FSH action throughout the **follicular phase**, promoting follicular growth and estrogen production. - This is a continuous regulatory mechanism, not a specific event occurring during ovulation itself.

Q: During early pregnancy (first trimester), estrogen is primarily secreted by which of the following structures?

Maternal ovary. ***Maternal ovary*** - During **early pregnancy** (first 8-10 weeks), the **corpus luteum** in the maternal ovary is the primary source of **estrogen** and **progesterone**, essential for maintaining the pregnancy until the placenta matures. - The corpus luteum is maintained by **hCG** (human chorionic gonadotropin) secreted by the developing placenta. - After the first trimester, the placenta takes over as the main source of estrogen production. *Fetal ovary* - The **fetal ovary** does not contribute to estrogen production during pregnancy. - The fetal ovary remains undeveloped during gestation and only becomes active after birth during puberty. *Pituitary* - The **pituitary gland** produces **gonadotropins** (LH and FSH) which regulate hormone production, but does not directly secrete estrogen. - During pregnancy, pituitary gonadotropin secretion is actually suppressed due to high levels of placental hormones. *Hypothalamus* - The **hypothalamus** secretes **GnRH** (gonadotropin-releasing hormone) to regulate the pituitary, but does not produce estrogen. - Its role is in the hormonal control cascade, not in direct steroid hormone synthesis.

Q: Ovulation is associated with a sudden rise in the level of which of the following hormones?

LH. ***LH*** - A rapid surge in **luteinizing hormone (LH)**, known as the **LH surge**, is the direct trigger for ovulation. - This **LH surge** stimulates the final maturation of the dominant follicle and its rupture, releasing the ovum. *Prolactin* - **Prolactin** is primarily involved in **milk production** and has no direct role in triggering ovulation. - High levels of **prolactin** can actually inhibit ovulation by suppressing gonadotropin-releasing hormone (GnRH). *Testosterone* - **Testosterone** is an androgen predominantly found in males, and while present in females, it is not responsible for triggering ovulation. - Its primary roles in females include contributing to **libido** and **bone density**. *Oxytocin* - **Oxytocin** plays a crucial role in uterine contractions during labor and milk ejection during breastfeeding. - It does not have a direct role in initiating the process of ovulation.

Q: Adequate steroidogenesis in the corpus luteum depends on serum levels of

LH. ***Correct: LH*** - **Luteinizing Hormone (LH)** is crucial for the **formation and maintenance of the corpus luteum** after ovulation. - LH directly stimulates the corpus luteum to produce **progesterone** and some **estrogen**, a process known as **steroidogenesis**. - LH binds to receptors on luteal cells and is the **primary hormonal driver** of corpus luteum function. *Incorrect: GnRH* - **Gonadotropin-releasing hormone (GnRH)** is released from the hypothalamus and stimulates the anterior pituitary to release FSH and LH. - While essential for the overall reproductive axis, **GnRH does not directly act on the corpus luteum** for steroidogenesis. *Incorrect: FSH* - **Follicle-stimulating hormone (FSH)** is primarily responsible for the growth and development of ovarian follicles during the follicular phase. - While FSH has some synergistic effects, its **direct role in corpus luteum steroidogenesis is minimal** compared to LH. *Incorrect: Oestrogen* - **Estrogen** is a steroid hormone produced by the ovaries, and later by the corpus luteum and placenta. - Estrogen is a **product of steroidogenesis, not its primary driver** in the corpus luteum.

Q: Which of the following C-21 steroid hormones is primarily associated with reproductive health?

Progesterone. ***Progesterone*** - **Progesterone** is a C-21 steroid hormone primarily involved in the **menstrual cycle**, **pregnancy**, and **embryogenesis**, making it crucial for female reproductive health. - It prepares the **endometrium** for the implantation of a fertilized egg and helps maintain pregnancy by preventing uterine contractions. *Cortisol* - **Cortisol** is a **glucocorticoid** primarily involved in stress response, metabolism, and immune function. - While it has broad effects, its main role is not directly associated with reproductive health. *Aldosterone* - **Aldosterone** is a **mineralocorticoid** that regulates **blood pressure** and **electrolyte balance** by controlling sodium and potassium levels. - It plays no direct role in reproductive health. *Corticosterone* - **Corticosterone** is a **glucocorticoid** and a precursor to aldosterone, mainly involved in stress response in some animals, similar to cortisol. - It is not a primary hormone for human reproductive health.

Q: What is the most likely consequence of prolonged testosterone treatment on male fertility?

Azoospermia. ***Azoospermia*** - Prolonged exogenous testosterone administration suppresses the **hypothalamic-pituitary-gonadal (HPG) axis**, leading to decreased **gonadotropin-releasing hormone (GnRH)**, then reduced **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)**. - Reduced FSH is critical for **spermatogenesis** in the seminiferous tubules, causing a severe reduction or complete absence of sperm in the ejaculate, known as azoospermia. *Decreased spermatogenesis* - While testosterone treatment does lead to decreased spermatogenesis, azoospermia represents the most severe and complete form of this reduction, indicating a total absence of sperm. - Spermatogenesis refers to the general process of sperm production, whereas **azoospermia** specifically describes the clinical outcome of no sperm. *Decreased sperm motility* - Poor sperm motility (**asthenozoospermia**) can occur due to various factors, but prolonged exogenous testosterone primarily affects **sperm production** rather than sperm movement. - Although sperm quality might decline, the most pronounced effect is on the **number of sperm** produced, potentially leading to complete absence. *Decreased gonadotropins* - Decreased gonadotropins (LH and FSH) are an **intermediate step** in the cascade, not the most likely direct consequence on sperm. - The suppression of LH and FSH then leads to the more direct testicular effect of reduced sperm production, ultimately culminating in **azoospermia**.

Q: Higher pulse frequency of GnRH is characteristic of which phase of the menstrual cycle?

Late follicular phase. ***Late follicular phase*** - As estrogen levels rise rapidly in the late follicular phase, the **GnRH pulse frequency increases significantly**, leading to the **LH surge** which triggers ovulation. - This higher frequency is crucial for sensitizing the pituitary to GnRH, maximizing LH release. *Early follicular phase* - The early follicular phase is characterized by a **lower frequency of GnRH pulses**, which favors **FSH secretion** to stimulate follicular growth. - As follicles mature, the estrogen feedback gradually increases leading to changes in pulse frequency. *Luteal phase* - During the luteal phase, the presence of **progesterone** exerts a strong negative feedback on the hypothalamus, leading to a **decreased frequency of GnRH pulses**. - This lower frequency helps maintain **LH and FSH at basal levels**, preventing new follicular development. *Menstrual phase* - The menstrual phase represents the beginning of a new cycle, with **GnRH pulse frequency being relatively low**, similar to the early follicular phase, due to low steroid hormone levels. - This low frequency is essential for **FSH support** in recruiting new follicles.

Question 1

Stimulation of the nerves of the pelvic parasympathetic plexus results in:

Accepted Answer

Penile erection

Answer

Contraction of the genital smooth muscle

Answer

Vasoconstriction

Answer

Constriction of the internal urethral sphincter

Question 2

During spermatogenesis, the number of chromosomes reduces to haploid at:

Accepted Answer

Meiosis-I

Answer

At mitosis

Answer

Meiosis-II

Answer

None of the options

Question 3

What hormones are secreted by the corpus luteum?

Accepted Answer

All of the options

Answer

Progesterone

Answer

Estrogen

Answer

Inhibin

Question 4

What physiological event occurs during ovulation?

Accepted Answer

FSH increases steroid synthesis in granulosa cells.

Answer

Inhibin A levels increase.

Answer

Activin enhances FSH action on granulosa cells.

Answer

Completion of the first meiotic division of the oocyte occurs just before ovulation.

Question 5

During early pregnancy (first trimester), estrogen is primarily secreted by which of the following structures?

Accepted Answer

Maternal ovary

Answer

Hypothalamus

Answer

Fetal ovary

Answer

Pituitary

Question 6

Ovulation is associated with a sudden rise in the level of which of the following hormones?

Accepted Answer

LH

Answer

Prolactin

Answer

Testosterone

Answer

Oxytocin

Question 7

Adequate steroidogenesis in the corpus luteum depends on serum levels of

Accepted Answer

LH

Answer

GnRH

Answer

FSH

Answer

Oestrogen

Question 8

Which of the following C-21 steroid hormones is primarily associated with reproductive health?

Accepted Answer

Progesterone

Answer

Corticosterone

Answer

Cortisol

Answer

Aldosterone

Question 9

What is the most likely consequence of prolonged testosterone treatment on male fertility?

Accepted Answer

Azoospermia

Answer

Decreased sperm motility

Answer

Decreased spermatogenesis

Answer

Decreased gonadotropins

Question 10

Higher pulse frequency of GnRH is characteristic of which phase of the menstrual cycle?

Accepted Answer

Late follicular phase

Answer

Luteal phase

Answer

Menstrual phase

Answer

Early follicular phase

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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