Reproductive Physiology Practice Questions

Q: Which of the following organs secretes zinc in large amount in man?

Prostate. ***Prostate*** - The **prostate gland** is a major source of zinc in seminal fluid, where it plays a critical role in **sperm maturation**, motility, and capacitation. - High zinc concentrations are found in prostatic secretions, contributing significantly to the overall zinc content of **semen**. *Epididymis* - The epididymis is primarily involved in the **maturation and storage of sperm**, rather than the secretion of large amounts of zinc. - While it has some zinc, its contribution to the total seminal zinc is much less significant compared to the prostate. *Vas* - The **vas deferens** transports sperm from the epididymis to the ejaculatory duct and does not primarily secrete zinc. - Its main function is **sperm transport**, not the production or secretion of seminal fluid components like zinc. *Seminal vesicle* - The **seminal vesicles** produce a significant portion of the seminal fluid, rich in fructose and prostaglandins, but they are not the primary source of zinc. - Their secretions provide energy for sperm and contribute to semen volume, while zinc is largely from the prostate.

Q: The principal steroid secreted by testes is

Testosterone. ***Testosterone*** - **Testosterone** is the primary **androgen** secreted by the **Leydig cells** in the testes, responsible for male sexual development and characteristics. - It plays crucial roles in **spermatogenesis**, muscle growth, bone density, and libido. *Dehydroepiandrosterone* - **Dehydroepiandrosterone (DHEA)** is a steroid hormone produced mainly by the **adrenal glands**, with a small amount also produced in the gonads. - While it is a precursor to other hormones, it is not the principal steroid secreted by the testes. *Dihydrotestosterone* - **Dihydrotestosterone (DHT)** is a more potent androgen that is converted from **testosterone** in target tissues by the enzyme **5-alpha-reductase**. - It is responsible for many androgenic effects but is not directly secreted by the testes in significant amounts. *Androstenedione* - **Androstenedione** is also an **androgen precursor** produced by both the adrenal glands and the gonads. - It can be converted into **testosterone** or **estrogen**, but it is not the main steroid secreted by the testes.

Q: The mammary gland is an estrogen-responsive organ. Which statement is NOT true about estrogen or the mammary gland?

Estrogen promotes growth of the lobules and acini. ***Estrogen promotes growth of the lobules and acini*** - This statement is **FALSE**. Estrogen primarily stimulates the **growth of the ductal system** in the mammary gland. - The development of **lobules and acini** (glandular tissue where milk is produced) is predominantly driven by **progesterone**, in cooperation with estrogen, not solely by estrogen. *Estrogen promotes growth of the duct system* - This is a **TRUE** statement. Estrogen is the primary hormone responsible for the **proliferation and elongation of the mammary ducts** during puberty and pregnancy. - It increases the number of epithelial cells within the ducts, preparing the gland for future milk production. *Estrogen is produced in the placenta* - This is a **TRUE** statement. During **pregnancy**, the placenta becomes a major site of estrogen production, particularly **estriol**, ensuring uterine growth and mammary gland development. - This placental estrogen production is critical for maintaining pregnancy and preparing the body for lactation. *Estrogen is produced primarily by the ovary* - This is a **TRUE** statement. In **premenopausal women**, the **ovaries** are the primary source of estrogen, particularly **estradiol**, which regulates the menstrual cycle and reproductive health. - After menopause, other tissues like adipose tissue become more significant for estrogen production through the conversion of androgens.

Q: Positive feedback action of estrogen for inducing luteinizing hormone surge is associated with which of the following steroid hormone ratios in peripheral circulation?

High estrogen : low progesterone. ***High estrogen : low progesterone*** - A sustained period of **high estrogen** levels, produced by the developing follicle, is crucial for triggering the **LH surge** through positive feedback. - At this pre-ovulatory stage, **progesterone levels remain relatively low**, as significant progesterone production only begins after ovulation from the corpus luteum. *High estrogen : high progesterone* - While high estrogen is required for the LH surge, **high progesterone levels** would typically occur *after* ovulation, suppressing LH rather than inducing its surge. - High progesterone usually exerts negative feedback on the hypothalamus and pituitary, preventing an LH surge. *Low estrogen : high progesterone* - **Low estrogen** levels are insufficient to exert the positive feedback necessary for an LH surge. - **High progesterone** during this phase would also inhibit GnRH and LH secretion. *Low estrogen : low progesterone* - Neither low estrogen nor low progesterone levels are conducive to the LH surge; this combination often characterizes the **early follicular phase** or the **late luteal phase/menstruation**, where ovarian activity is minimal. - The LH surge requires a specific hormonal milieu involving elevated estrogen.

Q: Nutrition to sperms is provided by:

Fructose. ***Fructose*** - **Fructose** is the primary sugar present in seminal fluid, providing the main energy source for **sperm motility**. - The seminal vesicles produce a fluid rich in fructose, which is crucial for energizing sperm during their journey through the female reproductive tract. *Glucose* - While glucose is a common energy source, it is not the **primary or most abundant sugar** specifically provided for sperm nutrition in seminal fluid. - Sperm primarily utilize fructose for their energy needs due to its high concentration in the **seminal vesicles' secretions**. *Galactose* - **Galactose** is a monosaccharide, but it is not a significant component of seminal fluid and does not serve as a primary nutrient for sperm. - It is typically metabolized by the liver and is not found in high concentrations in bodily fluids for direct energy provision to cells like sperm. *Starch* - **Starch** is a complex carbohydrate (polysaccharide) found in plant-based foods, not a simple sugar found in bodily fluids. - It needs to be broken down into monosaccharides (like glucose) for absorption and cannot be directly utilized by sperm for energy.

Q: Increased LH secretion just before ovulation is due to

Positive feed-back by estrogen. ***Positive feed-back by estrogen*** - The surge in **estrogen** from the dominant follicle during the late follicular phase stimulates the hypothalamus and anterior pituitary. - This high level of estrogen switches from negative to **positive feedback**, leading to a dramatic increase in **GnRH** and subsequently **LH** secretion. *Positive feed-back by FSH* - While **FSH** plays a role in follicular development, its primary function is to stimulate estrogen production, not directly trigger the LH surge via positive feedback. - FSH levels actually decline during the late follicular phase as estrogen levels rise, before a small secondary surge alongside LH. *Positive feed-back by progesterone* - **Progesterone** levels are low before ovulation and begin to rise significantly only after the **LH surge** and ovulation, secreted primarily by the corpus luteum. - While progesterone can contribute to a further LH surge in some contexts, it is not the primary initiator of the pre-ovulatory LH surge. *Positive feed-back by relaxin* - **Relaxin** is primarily involved in relaxing pelvic ligaments and softening the cervix, especially during pregnancy. - It does not play a role in the **positive feedback mechanism** that triggers the pre-ovulatory LH surge.

Q: Which of the following structures has the function of capacitation?

Female reproductive tract. ***Female reproductive tract*** - **Capacitation** is a biochemical process that occurs in the **female reproductive tract** (primarily the fallopian tubes and uterus), enabling sperm to gain the ability to fertilize an egg. - This process involves the removal of **cholesterol and glycoproteins** from the sperm head membrane, which modifies its motility and prepares it for the **acrosome reaction**. - Capacitation typically takes **5-6 hours** and is essential for successful fertilization. *Male reproductive tract* - The male reproductive tract produces and stores sperm, but it is **not the site where capacitation occurs**. - Sperm are immature and unable to fertilize an egg when they leave the male reproductive tract. - Sperm only gain fertilizing capacity after exposure to the female reproductive tract environment. *Vas deferens* - The vas deferens is a tube that transports sperm from the epididymis to the ejaculatory duct. - It is a part of the male reproductive tract and does **not contribute to capacitation**. *Capillary* - Capillaries are tiny blood vessels involved in nutrient and waste exchange, entirely unrelated to sperm function or capacitation. - This option is biologically implausible in the context of reproduction.

Q: Gonadotropin levels decline to prepubertal levels by age

6 month to 1 year of age.. ***6 months to 1 year of age*** * Following the **"mini-puberty" of infancy** (where gonadotropin levels surge in the first few months of life), LH and FSH levels progressively decline and typically reach **prepubertal nadir levels by 6-12 months of age**. * This represents the completion of the transitional decline from the neonatal gonadotropin surge to the quiescent prepubertal state. * Most current pediatric endocrinology references cite this timeframe as when gonadotropin levels stabilize at their lowest prepubertal values. *1 year to 2 years of age* * By this age, gonadotropin levels have **already declined** to prepubertal levels and are in a sustained quiescent phase. * This period represents the **maintenance** of low gonadotropin levels rather than the active decline period from infancy. * The initial nadir is typically reached earlier, during the first year of life. *2 years to 3 years of age* * Gonadotropin levels remain at prepubertal nadir during this period, having completed their decline much earlier. * This is part of the prolonged prepubertal quiescence that continues until pubertal activation begins years later. *3 years to 4 years of age* * Similar to 2-3 years, this represents a period of sustained **prepubertal quiescence** with stable low gonadotropin levels. * The decline from neonatal levels occurred years earlier, typically within the first year of life.

Q: Sperm acquires motility in:

Epididymis. ***Correct Answer: Epididymis*** - Sperm mature and acquire **motility** and the ability to fertilize an egg during their transit through the epididymis. - This process is known as **sperm maturation** or **epididymal maturation**, involving changes in sperm ultrastructure, metabolism, and surface molecules. - The epididymis also serves as the primary site for **sperm storage**. *Incorrect: Seminal vesicle* - The seminal vesicles produce a fluid rich in **fructose** (energy for sperm), prostaglandins, and clotting proteins, which contributes to semen volume but does not impart motility. - Seminal vesicles are **glands that secrete fluid**; they do not store sperm. *Incorrect: Ejaculatory duct* - The ejaculatory ducts are formed by the union of the vas deferens and the seminal vesicle ducts; their primary role is to **transport sperm** and seminal fluid into the urethra during ejaculation. - Sperm already possess motility by the time they reach this duct from the epididymis. *Incorrect: Testes* - Sperm are produced in the **seminiferous tubules** of the testes through a process called spermatogenesis. - Newly formed spermatozoa in the testes are **non-motile** and unable to fertilize an ovum.

Question 1

Which of the following organs secretes zinc in large amount in man?

Accepted Answer

Prostate

Answer

Epididymis

Answer

Vas

Answer

Seminal vesicle

Question 2

The principal steroid secreted by testes is

Accepted Answer

Testosterone

Answer

Dehydroepiandrosterone

Answer

Dihydrotestosterone

Answer

Androstenedione

Question 3

By which mechanism do LH and FSH primarily return to baseline levels after ovulation?

Accepted Answer

Negative feedback on gonadotropin-releasing hormone (GnRH) by progesterone

Answer

Negative feedback on GnRH from testosterone

Answer

LH surge

Answer

Negative feedback on GnRH by estradiol

Question 4

The mammary gland is an estrogen-responsive organ. Which statement is NOT true about estrogen or the mammary gland?

Accepted Answer

Estrogen promotes growth of the lobules and acini

Answer

Estrogen promotes growth of the duct system

Answer

Estrogen is produced in the placenta

Answer

Estrogen is produced primarily by the ovary

Question 5

Positive feedback action of estrogen for inducing luteinizing hormone surge is associated with which of the following steroid hormone ratios in peripheral circulation?

Accepted Answer

High estrogen : low progesterone

Answer

High estrogen : high progesterone

Answer

Low estrogen : high progesterone

Answer

Low estrogen : low progesterone

Question 6

Nutrition to sperms is provided by:

Accepted Answer

Fructose

Answer

Glucose

Answer

Galactose

Answer

Starch

Question 7

Increased LH secretion just before ovulation is due to

Accepted Answer

Positive feed-back by estrogen

Answer

Positive feed-back by FSH

Answer

Positive feed-back by progesterone

Answer

Positive feed-back by relaxin

Question 8

Which of the following structures has the function of capacitation?

Accepted Answer

Female reproductive tract

Answer

Male reproductive tract

Answer

Vas deferens

Answer

Capillary

Question 9

Gonadotropin levels decline to prepubertal levels by age

Accepted Answer

6 month to 1 year of age.

Answer

3 years to 4 years of age.

Answer

1 year to 2 years of age.

Answer

2 years to 3 years of age.

Question 10

Sperm acquires motility in:

Accepted Answer

Epididymis

Answer

Seminal vesicle

Answer

Ejaculatory duct

Answer

Testes

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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