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: The role of human placental lactogen is :

Supports fetal growth and development.. ***Supports fetal growth and development.*** - Human placental lactogen (hPL) acts as a **growth hormone** for the fetus, primarily by altering maternal metabolism to favor fetal nutrient supply. - It increases **maternal insulin resistance**, leading to higher maternal glucose and free fatty acids, which are then shunted to the fetus, supporting its growth and development. *Stimulate milk production* - **Prolactin**, secreted by the anterior pituitary, is the primary hormone responsible for stimulating milk production (lactogenesis). - While hPL has some structural similarity to growth hormone and prolactin, its primary role is not to directly stimulate milk production during pregnancy; rather, it prepares the breasts. *Promotes growth of breast for lactation.* - hPL, along with **estrogen** and **progesterone**, contributes to the **mammary gland development** during pregnancy, preparing the breasts for lactation. - However, its direct role is more about **mammary gland proliferation and differentiation** rather than initiation of milk production. *Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.* - This is a highly detailed and largely accurate description of *how* hPL supports fetal growth and development, making it a mechanism rather than the primary, concise role. - It describes the metabolic changes induced by hPL, which ultimately lead to the **support of fetal growth and development**.

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 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: 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: 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: 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: 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.

Q: What is the primary gene responsible for gonads to testes differentiation?

SRY gene. ***SRY gene*** - The **SRY gene** (Sex-determining Region Y) is located on the **Y chromosome** and is the **primary master regulator** that initiates the cascade of events leading to testicular development from the undifferentiated bipotential gonad. - Its gene product, the **SRY protein**, acts as a transcription factor that directly upregulates downstream genes like **SOX9**, triggering male sex determination. *WNT-4 gene* - The **WNT-4 gene** is primarily involved in **female sex differentiation**, promoting ovarian development and actively suppressing male differentiation pathways. - Its expression is downregulated in males during gonad development, allowing testicular differentiation to proceed. *DAX1 gene* - The **DAX1 gene** (Dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on chromosome X, gene 1) is a negative regulator of male sexual differentiation. - In females, it contributes to ovarian development; overexpression in males can lead to **sex reversal** and gonadal dysgenesis. *SOX9 gene* - While **SOX9** is critical for testicular differentiation, it acts **downstream** of SRY and is not the primary initiator. - SRY activates SOX9, which then maintains testicular development through positive feedback loops and regulation of anti-Müllerian hormone (AMH).

Q: In the breast, lactiferous ducts are formed under the influence of which hormone?

Estrogen. ***Estrogen*** - **Estrogen** plays a primary role in the development and branching of the **lactiferous ducts** in the breast. - It stimulates the proliferation of ductal epithelial cells, contributing to the growth of the duct system. *Progesterone* - **Progesterone** is primarily responsible for the development of the **lobuloalveolar system** and secretory differentiation within the breast. - While essential for lactation, its main function is not duct formation but rather the maturation of secretory units. *LH* - **Luteinizing hormone (LH)** is crucial for ovulation and the formation of the **corpus luteum** in the ovaries. - It has no direct role in the structural development of the lactiferous ducts in the breast. *FSH* - **Follicle-stimulating hormone (FSH)** is essential for the growth and maturation of **ovarian follicles**. - It does not directly influence the formation or development of lactiferous ducts in the breast.

Question 1

Oxygen consumption increases in pregnancy by

Accepted Answer

20%

Answer

10%

Answer

30%

Answer

40%

Question 2

The role of human placental lactogen is :

Accepted Answer

Supports fetal growth and development.

Answer

Stimulate milk production

Answer

Promotes growth of breast for lactation.

Answer

Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.

Question 3

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 4

Which hormone is primarily responsible for galactopoiesis?

Accepted Answer

Prolactin

Answer

Growth hormone

Answer

Insulin

Answer

Oxytocin

Question 5

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 6

Acrosome reaction is seen in?

Accepted Answer

Fertilization

Answer

Spermatogenesis

Answer

Oogenesis

Answer

Menstruation

Question 7

Labour pain in uterus is carried by

Accepted Answer

Sympathetic nerves

Answer

Pudendal nerve

Answer

Parasympathetic nerves

Answer

Splanchnic nerve

Question 8

Spermatogenesis begins at -

Accepted Answer

Puberty

Answer

Birth

Answer

5 years

Answer

18 years

Question 9

What is the primary gene responsible for gonads to testes differentiation?

Accepted Answer

SRY gene

Answer

WNT-4 gene

Answer

DAX1 gene

Answer

SOX9 gene

Question 10

In the breast, lactiferous ducts are formed under the influence of which hormone?

Accepted Answer

Estrogen

Answer

Progesterone

Answer

LH

Answer

FSH

Reproductive Physiology — MCQs

Reproductive Physiology — MCQs

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