Reproductive Physiology — MCQs

Reproductive Physiology Indian Medical PG Practice Questions and MCQs

Question 401: Sperm remain in the epididymis for ____ days?

A. 25-30 days
B. 5-7 days
C. 2-3 days
D. 12-14 days (Correct Answer)

Explanation: ***12-14 days*** - Sperm typically spends **12-14 days** maturing and being stored in the epididymis. - This time allows for the acquisition of **motility** and **fertilizing capacity**. *25-30 days* - This duration is **too long** for the typical transit and storage time of sperm in the epididymis. - Extended retention might indicate an issue with **ejaculation** or sperm transport. *5-7 days* - This period is **too short** for sperm to fully mature and gain maximal fertilizing capacity within the epididymis. - Sperm would still be relatively immobile and **unfertile** at this point. *2-3 days* - This duration is significantly **too short** for the necessary maturation process to occur in the epididymis. - Sperm would have **very limited motility** and fertilizing ability.

Question 402: Which of the following is not seen in humans?

A. Estrous Cycle (Correct Answer)
B. Menstrual Cycle
C. Ovarian Cycle
D. Endometrial Cycle

Explanation: ***Estrous Cycle*** - The **estrous cycle** is characteristic of most mammals, where females are sexually receptive only during a specific period called **estrus** or "heat." - This cycle typically involves the reabsorption of the **endometrium** if fertilization does not occur, rather than shedding. *Menstrual Cycle* - The **menstrual cycle** is the reproductive cycle found in humans and some other primates, characterized by the monthly shedding of the **endometrium** if pregnancy does not occur. - It involves hormonal fluctuations that prepare the uterus for potential pregnancy and results in **menstruation**. *Ovarian Cycle* - The **ovarian cycle** is a series of events in the human ovary that leads to the maturation of an **oocyte** and its release (ovulation), as well as the formation of the **corpus luteum**. - It is an integral part of the broader menstrual cycle in humans, influencing the **uterine changes**. *Endometrial cycle* - The **endometrial cycle** (or uterine cycle) refers to the cyclical changes occurring in the **endometrium** of the human uterus in response to hormonal fluctuations, primarily estrogen and progesterone. - These changes prepare the uterus for implantation of an **embryo** and culminate in menstruation if pregnancy does not occur.

Question 403: The following changes occur in the urinary system in pregnancy except:

A. Increased RBF
B. Increased GFR
C. Increased activity of ureters (Correct Answer)
D. Hypertrophy of bladder musculature

Explanation: ***Increased activity of ureters*** - Ureters actually experience **decreased peristaltic activity** and **dilation** during pregnancy due to hormonal influences (progesterone) and mechanical compression. - This leads to **urinary stasis** and an increased risk of urinary tract infections, a common complication of pregnancy. *Increased RBF* - **Renal blood flow (RBF)** significantly **increases** during pregnancy, primarily due to vasodilation induced by hormones like relaxin and nitric oxide. - This increase in RBF is essential to accommodate the increased metabolic demands and waste product excretion during pregnancy. *Increased GFR* - **Glomerular filtration rate (GFR)** also **increases** by 30-50% during pregnancy, reflecting the increased RBF and the need to filter a larger volume of plasma. - This elevated GFR can lead to lower serum creatinine and urea levels compared to the non-pregnant state. *Hypertrophy of bladder musculature* - The **bladder musculature undergoes hypertrophy** during pregnancy as a physiological adaptation to accommodate the growing uterus and maintain bladder function. - This hypertrophy helps the bladder withstand increased pressure and prepare for the demands of labor and delivery.

Question 404: How many hours does human sperm remain viable in the female genital tract?

A. 72-96 hrs (Correct Answer)
B. 24-48 hrs
C. 12-24 hrs
D. 6-8 hrs

Explanation: ***72-96 hrs*** - Sperm can survive in the **female reproductive tract** for approximately **3-4 days (72-96 hours)**, which represents the typical maximum viability period. - This extended viability is due to the protective environment and **nutrient supply** within the female tract, particularly in the cervical crypts and fallopian tubes. - This duration represents the **commonly accepted range** for sperm viability in standard medical examinations and determines the fertile window for conception. *24-48 hrs* - While 24-48 hours represents a significant portion of sperm viability, many sperm can remain viable for longer periods, up to 3-4 days under optimal conditions. - This timeframe underestimates the full **fertile window** that contributes to successful fertilization potential. *12-24 hrs* - This period is generally considered the lifespan of the **ovum (egg)** after ovulation, not the sperm. - It significantly **underestimates** the actual survival time of sperm in the female reproductive tract. *6-8 hrs* - This duration is far too short for sperm viability in the female reproductive tract; sperm can survive much longer in the protective cervical and tubal environment. - Such a short window would severely limit the chances of **fertilization** and is not physiologically accurate.

Question 405: MIS is secreted by?

A. Sertoli cell (Correct Answer)
B. Leydig cell
C. Granulosa cells
D. Theca cells

Explanation: ***Sertoli cell*** - **Sertoli cells** in the testes secrete **Müllerian Inhibiting Substance (MIS)**, also known as anti-Müllerian hormone (AMH) - MIS causes **regression of Müllerian ducts** during male sexual differentiation, preventing development of female internal reproductive organs - Secretion begins around 8 weeks of fetal development and continues throughout life *Leydig cell* - **Leydig cells** produce **testosterone and other androgens** - While essential for masculinization and male sexual development, they do not secrete MIS - Located in the interstitial space between seminiferous tubules *Granulosa cells* - **Granulosa cells** are found in the **ovarian follicles** in females - They also produce AMH (anti-Müllerian hormone), but in the female reproductive context - In females, AMH regulates follicular development, not Müllerian duct regression *Theca cells* - **Theca cells** are also ovarian cells that produce **androgens** as precursors for estrogen synthesis - They work in conjunction with granulosa cells in the two-cell, two-gonadotropin model - They do not secrete MIS

Question 406: Puberty happens due to pulsatile release of -

A. Testosterone
B. LH/ICSH
C. GnRH (Correct Answer)
D. Estrogen

Explanation: ***GnRH*** - Puberty is initiated by the pulsatile release of **Gonadotropin-Releasing Hormone (GnRH)** from the hypothalamus. - This pulsatile release primes the anterior pituitary to secrete gonadotropins, **Luteinizing Hormone (LH)** and **Follicle-Stimulating Hormone (FSH)**. *Testosterone* - **Testosterone** is a sex hormone whose release is stimulated by LH, but it is not the primary initiator of puberty. - Its levels rise later in puberty, driven by the pituitary-gonadal axis, causing the development of **secondary sexual characteristics** in males. *LH/ICSH* - **Luteinizing Hormone (LH)** and **Interstitial Cell-Stimulating Hormone (ICSH)** (the male equivalent of LH) are pituitary hormones whose release is stimulated by GnRH. - They act on the gonads to stimulate sex hormone production, but their release is a consequence, not the initial trigger, of the pulsatile activity related to puberty. *Estrogen* - **Estrogen** is a sex hormone primarily produced in females in response to FSH and LH. - Similar to testosterone, its elevated levels are a downstream effect of the hypothalamic-pituitary-gonadal axis activation during puberty, leading to the development of female secondary sexual characteristics.

Question 407: Mullerian inhibiting substance (MIS) is produced by:

A. Stroma
B. Sertoli cells (Correct Answer)
C. Germ cells
D. Leydig cells

Explanation: ***Sertoli cells*** - **Sertoli cells** in the fetal testes produce **Müllerian inhibiting substance (MIS)**, also known as anti-Müllerian hormone (AMH). - **MIS** is crucial for the regression of the paramesonephric (Müllerian) ducts in male fetuses, preventing the development of female internal reproductive organs. *Stroma* - **Stromal cells** in the gonads provide structural support and a microenvironment for germ cell development but do not primarily produce MIS. - Their primary roles involve hormone synthesis and interaction with germ cells and somatic cells. *Germ cells* - **Germ cells** (spermatogonia or oocytes) are the precursors to sperm and eggs, responsible for genetic transmission. - They do not produce **Müllerian inhibiting substance (MIS)**; their role is focused on meiosis and reproduction. *Leydig cells* - **Leydig cells** in the testes produce **androgens**, primarily testosterone, which is essential for the development of male internal and external genitalia. - They do not produce **Müllerian inhibiting substance (MIS)**; their function is distinct from Müllerian duct regression.

Question 408: In development of male fetus following statements are true except

A. During intrauterine life, testes do not produce hormones essential for male development. (Correct Answer)
B. Around 8 weeks internal and external genitalia differentiates into male pattern
C. Gene on short arm of Y chromosome directs testes development
D. Antimullerian hormone inhibits development of mullerian system in male fetus

Explanation: *During intrauterine life, testes do not produce hormones essential for male development.* - This statement is **INCORRECT** and is the answer to this EXCEPT question. - The **fetal testes** actively produce essential hormones during intrauterine life including **testosterone** (from Leydig cells) and **Anti-Müllerian Hormone/AMH** (from Sertoli cells). - Testosterone is converted to **dihydrotestosterone (DHT)** which drives development of male external genitalia. - These hormones are absolutely essential for **masculinization of internal and external genitalia** and regression of female structures. ***Around 8 weeks internal and external genitalia differentiates into male pattern.*** - This statement is correct. Sexual differentiation begins around **7-8 weeks of gestation**. - Under the influence of **testosterone and DHT** produced by fetal testes, the indifferent genitalia differentiate into male pattern. - The Wolffian ducts develop into male internal structures (epididymis, vas deferens, seminal vesicles). ***Gene on short arm of Y chromosome directs testes development.*** - This statement is correct. The **SRY gene (Sex-determining Region Y)** located on the **short arm (p arm) of the Y chromosome** is the master regulator of testis determination. - SRY expression triggers differentiation of the indifferent gonads into testes around 6-7 weeks. - Without SRY, the default pathway leads to ovarian development. ***Antimullerian hormone inhibits development of mullerian system in male fetus.*** - This statement is correct. **Anti-Müllerian Hormone (AMH)**, also called Müllerian-Inhibiting Substance (MIS), is secreted by **Sertoli cells** of the fetal testes. - AMH causes **regression of the Müllerian ducts** (paramesonephric ducts) around 8-10 weeks. - Without AMH, these ducts would develop into fallopian tubes, uterus, and upper vagina.

Question 409: Motor protein responsible for sperm motility is -

A. Actin
B. Dynein (Correct Answer)
C. Myosin
D. Kinesin

Explanation: ***Dynein*** - **Dynein** is a motor protein that powers the movement of **cilia** and **flagella**, including the tail of sperm. - It generates the **sliding motion** between microtubules within the axoneme, leading to the characteristic whip-like movement of sperm. *Actin* - **Actin** is a major component of the cytoskeleton in many cells and is involved in cell shape, division, and muscle contraction. - While present in sperm, actin is not directly responsible for the **propulsive motility** of the flagellum. *Myosin* - **Myosin** is a motor protein primarily associated with **muscle contraction** and cellular transport along actin filaments. - It does not play a direct role in the **flagellar movement** of sperm. *Kinesin* - **Kinesin** is a motor protein that typically moves along **microtubules**, transporting vesicles and organelles, usually away from the cell body (anterograde transport). - It is not involved in the actual **motility mechanism** of sperm flagella.

Question 410: Which of the following is false as physiological change in pregnancy?

A. Increase GFR
B. Increase total protein (Correct Answer)
C. Increase cardiac output
D. Increase plasma volume

Explanation: ***Increase total protein*** - During pregnancy, **plasma volume increases disproportionately more than the increase in red blood cell mass**, leading to hemodilution. - This hemodilution results in a **decrease in the concentration of total plasma proteins and albumin**, making this statement false. *Increase GFR* - **Glomerular filtration rate (GFR) increases significantly** during pregnancy (by 30-50%) due to increased renal plasma flow. - This physiological adaptation helps to clear the increased metabolic waste products produced by both the mother and the fetus. *Increase cardiac output* - **Cardiac output increases by 30-50%** during pregnancy, primarily due to increases in both heart rate and stroke volume. - This increased cardiac output ensures adequate blood supply to the uterus, placenta, and other maternal organs. *Increase plasma volume* - **Plasma volume increases substantially (up to 40-50%)** during pregnancy, starting in the first trimester and continuing until term. - This expansion of plasma volume is crucial for meeting the increased circulatory demands of pregnancy and supporting placental perfusion.

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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