Reproductive Physiology Practice Questions

Q: Oxygen consumption increases in pregnancy by

20%. ***20%*** - During **pregnancy**, the maternal **metabolic rate increases** to support fetal growth and the physiological changes occurring in the mother's body. - This increased metabolic demand leads to a **rise in oxygen consumption** by approximately 20% compared to the non-pregnant state. *10%* - A 10% increase is an **underestimation** of the physiological change in oxygen consumption during pregnancy. - The demands of supporting a growing fetus and increased maternal tissue mass require a more substantial metabolic adjustment. *30%* - While oxygen consumption does increase significantly, a 30% rise is generally considered an **overestimation** of the average increase. - The typical physiological adaptation usually falls within the 15-25% range. *40%* - A 40% increase in oxygen consumption would represent an **extreme physiological demand** that is not typically observed during an uncomplicated pregnancy. - Such a drastic increase might indicate underlying pathology rather than normal adaptation.

Q: Testes are not palpable in

SRY deletion. ***SRY deletion*** - **SRY (Sex-determining Region Y) gene** is the master regulator of male sex determination on the Y chromosome; its deletion in 46,XY individuals results in **Swyer syndrome** (pure gonadal dysgenesis). - Without functional SRY, **testes fail to develop entirely**, and the gonads remain as non-functional **streak gonads** rather than differentiating into either testes or ovaries. - Result: **No palpable testes** because testicular tissue never forms; individuals develop female external genitalia despite XY karyotype. *DAX1 deletion* - DAX1 (NR0B1) normally **antagonizes testicular development** and supports adrenal/gonadal development. - **Deletion of DAX1** would actually **reduce anti-testis effects**, allowing testicular development to proceed more readily if SRY is present. - DAX1 **duplications** (not deletions) can impair male development; deletions cause **adrenal hypoplasia congenita** but do not prevent testicular formation. *WNT-4 gene mutation* - **WNT4** promotes **ovarian development** and opposes male differentiation pathways in normal female development. - **Loss-of-function mutations** in WNT4 do not prevent testicular development in 46,XY individuals where SRY is present and functional. - WNT4 overexpression (not loss-of-function mutation) could theoretically interfere with male development, but standard WNT4 mutations do not cause absent testes. *RSPO-1 gene mutation* - **RSPO1** (R-spondin 1) enhances **Wnt/β-catenin signaling** and supports ovarian differentiation; primarily relevant in 46,XX sex development. - Loss-of-function mutations in RSPO1 lead to **46,XX testicular/ovotesticular DSD**, where testicular tissue develops inappropriately in XX individuals. - In 46,XY individuals with functional SRY, RSPO1 mutations would **not prevent testicular development**, so testes would be palpable.

Q: Which hormone is primarily responsible for galactopoiesis?

Prolactin. ***Prolactin*** - **Prolactin** is the primary hormone responsible for **galactopoiesis**, which is the maintenance of milk production after initiation. - It stimulates the **mammary epithelial cells** to synthesize and secrete milk components. *Growth hormone* - While growth hormone has some synergistic effects on milk production, it is not the **primary hormone** for galactopoiesis. - Its main roles include promoting **growth** and regulating **metabolism**. *Insulin* - **Insulin** is essential for general metabolic support and cell function, which indirectly supports milk production. - However, it does not directly stimulate the **synthesis or secretion of milk components**. *Oxytocin* - **Oxytocin** is responsible for the **milk ejection reflex** (let-down), causing milk to be released from the mammary glands. - It does not directly control the **synthesis or production** of milk itself.

Q: Which of the following is not a component of a mature sperm cell?

Endoplasmic reticulum. ***Endoplasmic reticulum*** - The **endoplasmic reticulum** is prominent in spermatogonia and spermatocytes but largely absent in **mature sperm** as organelles are shed during spermiogenesis to reduce cell volume. - Its primary functions of protein synthesis and lipid metabolism are not required in a terminally differentiated, motile cell like a mature sperm. *Golgi apparatus* - The **Golgi apparatus** reorganizes during spermiogenesis to form the **acrosome**, which is a crucial structure for fertilization. - While the distinct Golgi stacks are not present, its modified derivative, the acrosome, is an essential component. *Mitochondria* - **Mitochondria** are abundant in the midpiece of the sperm tail, arranged in a spiral sheath. - They are vital for generating the **ATP** required for the flagellum's motility, enabling the sperm to swim. *Lysosome* - Although typical lysosomes are not found, the **acrosome** of the sperm is considered a modified lysosome. - The acrosome contains **hydrolytic enzymes** similar to lysosomes, which are critical for penetrating the egg's outer layers during fertilization.

Q: Which hormone is primarily responsible for maintaining the luteal phase of the menstrual cycle?

Progesterone. ***Progesterone*** - **Progesterone**, secreted by the **corpus luteum** after ovulation, is crucial for maintaining the luteal phase by preparing the **endometrium** for implantation. - It causes the endometrial lining to thicken and become more vascularized, creating a suitable environment for a fertilized egg. *Estrogen* - While **estrogen** is important throughout the menstrual cycle for endometrial proliferation, its primary role is in the **follicular phase**, not the maintenance of the luteal phase. - Estrogen levels are higher during the follicular phase, promoting the growth of the dominant follicle. *Follicle-stimulating hormone (FSH)* - **FSH** is primarily responsible for stimulating the growth and development of **ovarian follicles** during the follicular phase. - Its levels decrease significantly after ovulation, and it does not play a direct role in maintaining the luteal phase. *Luteinizing hormone (LH)* - **LH** triggers **ovulation** and the formation of the **corpus luteum** from the ruptured follicle. - While essential for initiating the luteal phase, its levels decline afterward, and it's not the primary hormone for *maintaining* the corpus luteum's function.

Q: Acrosome reaction is seen in?

Fertilization. ***Fertilization*** - The **acrosome reaction** is a crucial event that occurs when a **spermatozoon** comes into contact with the **zona pellucida** surrounding the oocyte. - This reaction involves the release of **hydrolytic enzymes** from the acrosome, which are essential for the sperm to penetrate the zona pellucida and fuse with the oocyte membrane. *Spermatogenesis* - **Spermatogenesis** is the process of sperm formation in the testes, involving meiosis and spermiogenesis. - While it produces the sperm cell with an acrosome, the **acrosome reaction itself does not occur** during this developmental stage. *Oogenesis* - **Oogenesis** is the process of egg cell formation in the ovaries. - This process is entirely **separate from sperm function** and does not involve the acrosome or the acrosome reaction. *Menstruation* - **Menstruation** is the monthly shedding of the uterine lining in females when fertilization does not occur. - This process is part of the female reproductive cycle and has **no direct involvement with sperm or the acrosome reaction**.

Q: Penile erection is mediated by which system?

Parasympathetic system via muscarinic receptors. ***Parasympathetic system via muscarinic receptors*** - Penile erection is primarily a **parasympathetic response** mediated by the **pelvic splanchnic nerves (S2-S4)**. - The key mechanism involves **nitric oxide (NO)** release from non-adrenergic, non-cholinergic (NANC) neurons, which activates guanylate cyclase → increases cGMP → smooth muscle relaxation in the **corpora cavernosa**. - **Acetylcholine acting on muscarinic receptors** plays a **supportive role** by enhancing NO release and contributing to vasodilation. - For exam purposes, the parasympathetic system (with its cholinergic muscarinic component) is the recognized answer. *Parasympathetic system via nicotinic receptors* - **Nicotinic receptors** are located at **autonomic ganglia** and **neuromuscular junctions**, not at the effector sites in penile vasculature. - While nicotinic transmission occurs at the parasympathetic ganglia, the post-ganglionic fibers act on **muscarinic receptors** and release **NO** at the target tissue. - This option confuses the ganglionic transmission with the effector mechanism. *Sympathetic system via α-receptors* - The **sympathetic nervous system** via **α1-adrenergic receptors** causes **vasoconstriction** and maintains penile **flaccidity** (detumescence). - Sympathetic activation is responsible for **ejaculation** and the resolution phase after orgasm. - Activation of α-receptors opposes erection by causing smooth muscle contraction. *Sympathetic system via β-receptors* - **β-adrenergic receptors** are involved in functions like **cardiac stimulation** and **bronchodilation**, but play no significant role in penile erection. - The sympathetic system's role in sexual function is primarily through **α-receptors** (detumescence and ejaculation), not β-receptors.

Q: Labour pain in uterus is carried by

Sympathetic nerves. ***Sympathetic nerves*** - Pain signals from the **uterus** during the first stage of labor (cervical dilation and uterine contractions) are transmitted via **visceral afferent fibers that accompany the sympathetic nerves** through the **hypogastric plexus**. - These fibers synapse in the **thoracolumbar spinal cord** at **T10-L1 segments**, leading to referred pain in these dermatomes. - The pathway is: Uterus → Uterine plexus → Superior hypogastric plexus → Sympathetic chain → T10-L1 dorsal roots. *Splanchnic nerve* - While visceral afferents do travel with splanchnic nerves in the thoracoabdominal region, for **uterine pain** specifically, the standard medical terminology refers to **sympathetic nerves** and the **hypogastric plexus** as the primary pathway. - Splanchnic nerves typically refer to thoracic sympathetic contributions (T5-T12) to upper abdominal viscera. *Pudendal nerve* - The **pudendal nerve (S2-S4)** primarily innervates the perineum, external genitalia, and pelvic floor structures. - It transmits pain during the **second stage of labor**, particularly with stretching of the perineum and vaginal distension, but **not from the uterus itself**. *Parasympathetic nerves* - **Parasympathetic innervation (S2-S4 via pelvic splanchnic nerves)** to the uterus influences motor function but does **not transmit nociceptive (pain) signals** during labor. - These nerves are involved in visceral reflexes and efferent control, not the primary afferent pain pathway.

Q: Which of the following statements about seminal vesicles is FALSE?

Stores sperm. ***Stores sperm*** - This statement is **false** because the **seminal vesicles** produce fluid components of semen but **do not store sperm**. - Sperm are primarily stored in the **epididymis** until ejaculation [1]. *Contains large amount of fructose* - The seminal vesicles contribute **fructose** to the semen, which serves as the primary **energy source for sperm motility**. - A large amount of fructose is characteristic of seminal vesicle secretions. *Does not store sperm* - This statement is **true** because the primary function of seminal vesicles is to produce **seminal fluid**, not to store sperm [1]. - Sperm maturation and storage occur in the **epididymis**. *Secretion of seminal vesicle gives a mucoid consistency to semen* - The secretions from the seminal vesicles, including **fructose** and **fibrinogen**, contribute to the **gel-like, mucoid consistency** of semen upon ejaculation. - **Fibrinogen** aids in the coagulation of semen after ejaculation, forming a temporary clot.

Q: Spermatogenesis begins at -

Puberty. ***Puberty*** - **Spermatogenesis**, the process of sperm production, is initiated and sustained by the surge of **gonadotropin-releasing hormone (GnRH)**, which begins at puberty. - This hormonal signal leads to the secretion of **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)**, crucial for testicular function and sperm development. *Birth* - At birth, the male testes contain **spermatogonia**, but these cells remain dormant and do not begin active sperm production. - Hormonal levels at birth are not conducive to initiating spermatogenesis. *5 years* - While some hormonal changes occur in early childhood, they are not sufficient to trigger the full process of spermatogenesis. - The reproductive system is still in a quiescent state before puberty. *18 years* - By 18 years, spermatogenesis is typically well-established and has been ongoing for several years, having started at puberty. - This age marks a period of full reproductive maturity, not the initiation of sperm production.

Question 1

Oxygen consumption increases in pregnancy by

Accepted Answer

20%

Answer

10%

Answer

30%

Answer

40%

Question 2

Testes are not palpable in

Accepted Answer

SRY deletion

Answer

DAX 1 deletion

Answer

WNT- 4 gene mutation

Answer

RSPO-1 gene mutation

Question 3

Which hormone is primarily responsible for galactopoiesis?

Accepted Answer

Prolactin

Answer

Growth hormone

Answer

Insulin

Answer

Oxytocin

Question 4

Which of the following is not a component of a mature sperm cell?

Accepted Answer

Endoplasmic reticulum

Answer

Lysosome

Answer

Golgi apparatus

Answer

Mitochondria

Question 5

Which hormone is primarily responsible for maintaining the luteal phase of the menstrual cycle?

Accepted Answer

Progesterone

Answer

Estrogen

Answer

Follicle-stimulating hormone (FSH)

Answer

Luteinizing hormone (LH)

Question 6

Acrosome reaction is seen in?

Accepted Answer

Fertilization

Answer

Spermatogenesis

Answer

Oogenesis

Answer

Menstruation

Question 7

Penile erection is mediated by which system?

Accepted Answer

Parasympathetic system via muscarinic receptors

Answer

Parasympathetic system via nicotinic receptors

Answer

Sympathetic system via α-receptors

Answer

Sympathetic system via β-receptors

Question 8

Labour pain in uterus is carried by

Accepted Answer

Sympathetic nerves

Answer

Pudendal nerve

Answer

Parasympathetic nerves

Answer

Splanchnic nerve

Question 9

Which of the following statements about seminal vesicles is FALSE?

Accepted Answer

Stores sperm

Answer

Does not store sperm

Answer

Secretion of seminal vesicle gives a mucoid consistency to semen

Answer

Contains large amount of fructose

Question 10

Spermatogenesis begins at -

Accepted Answer

Puberty

Answer

Birth

Answer

5 years

Answer

18 years

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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