Chapter: Endocrinology
Topic: Steroidogenesis
Subtopic: Aromatase Enzyme Deficiency
Keyword Definitions:
• Aromatase: Enzyme that converts androgens to estrogens.
• Estrogen: Female sex hormone essential for reproduction.
• Testosterone: Primary male androgen, precursor for estrogen.
• Steroidogenesis: Hormone production from cholesterol.
• Cortisol: Stress hormone from adrenal cortex.
• Mineralocorticoids: Adrenal hormones regulating sodium and water balance.
Lead Question - 2013
Deficiency of enzyme aromatase leads to deficiency of which hormone?
a) Cortisol
b) Estrogen
c) Testosteron
d) Mineral corticoids
Explanation: Aromatase converts androgens like testosterone and androstenedione into estrogens. Deficiency results in impaired estrogen production, leading to virilization and infertility in females. Cortisol and mineralocorticoids are unaffected. Thus, the correct answer is Estrogen, the hormone directly deficient in aromatase deficiency.
1) Aromatase is located mainly in?
a) Ovary and placenta
b) Adrenal medulla
c) Liver
d) Kidney
Explanation: Aromatase is highly expressed in ovaries and placenta, converting androgens into estrogens during reproductive years and pregnancy. This ensures sufficient estrogen levels for female physiology. Hence, the correct answer is Ovary and placenta.
2) A 20-year-old female presents with primary amenorrhea, tall stature, and virilization. Likely cause?
a) Estrogen deficiency due to aromatase defect
b) Cortisol deficiency
c) Progesterone deficiency
d) Growth hormone excess
Explanation: Aromatase deficiency prevents conversion of testosterone to estrogen, causing virilization, amenorrhea, and tall stature due to delayed epiphyseal closure. Thus, the correct answer is Estrogen deficiency due to aromatase defect.
3) Which gene codes for aromatase enzyme?
a) CYP11B1
b) CYP17A1
c) CYP19A1
d) CYP21A2
Explanation: The aromatase enzyme is encoded by the CYP19A1 gene, located on chromosome 15. Mutations in this gene result in impaired estrogen synthesis, leading to aromatase deficiency syndromes. Correct answer is CYP19A1.
4) A pregnant woman with aromatase deficiency presents with virilization. Cause?
a) Fetal androgen excess
b) Maternal thyroid defect
c) Excess prolactin
d) High cortisol
Explanation: In aromatase deficiency, fetal androgens cannot be converted into estrogens, leading to maternal virilization during pregnancy. Hence, the correct answer is Fetal androgen excess.
5) Which of the following hormones is increased in aromatase deficiency?
a) Testosterone
b) Estrogen
c) Cortisol
d) Aldosterone
Explanation: In aromatase deficiency, androgens like testosterone accumulate because they are not converted into estrogens. Therefore, androgen levels are high while estrogen is low. Correct answer is Testosterone.
6) A 22-year-old female with aromatase deficiency presents with osteoporosis. Cause?
a) Cortisol excess
b) Estrogen deficiency
c) Progesterone deficiency
d) GH deficiency
Explanation: Estrogen is essential for bone mineralization and growth plate closure. Its deficiency in aromatase defect leads to osteoporosis and tall stature due to delayed epiphyseal fusion. Thus, the correct answer is Estrogen deficiency.
7) In males, aromatase is important for?
a) Spermatogenesis
b) Conversion of testosterone to estrogen
c) Testosterone secretion
d) LH production
Explanation: In males, aromatase converts testosterone to estrogen, which is vital for spermatogenesis and bone health. Hence, the correct answer is Conversion of testosterone to estrogen.
8) A male with aromatase deficiency is likely to show?
a) Early epiphyseal closure
b) Tall stature with osteoporosis
c) Short stature with obesity
d) Hypothyroidism
Explanation: Without estrogen, epiphyseal plates do not close, leading to tall stature and reduced bone density. Thus, the correct answer is Tall stature with osteoporosis.
9) Which laboratory finding supports aromatase deficiency?
a) Low estrogen, high androgen
b) Low cortisol, high estrogen
c) High progesterone, low testosterone
d) High mineralocorticoids
Explanation: Aromatase deficiency is confirmed by low estrogen with elevated androgens. Cortisol and mineralocorticoids remain normal. Hence, the correct answer is Low estrogen, high androgen.
10) Treatment of aromatase deficiency in females involves?
a) Cortisol supplementation
b) Estrogen replacement therapy
c) Progesterone only
d) Testosterone injections
Explanation: Estrogen replacement therapy is given to correct estrogen deficiency, prevent osteoporosis, and support normal secondary sexual characteristics. Thus, the correct answer is Estrogen replacement therapy.
Chapter: Reproductive Physiology
Topic: Oogenesis
Subtopic: Meiotic Arrest in Oocytes
Keyword Definitions:
• Oogenesis: Process of female gamete formation.
• Primary oocyte: Oocyte arrested in prophase I of meiosis.
• Diplotene stage: Substage of prophase I where oocytes arrest until puberty.
• Meiosis I: First meiotic division producing secondary oocyte and polar body.
• Metaphase II: Arrest stage of secondary oocyte until fertilization.
• Pachytene stage: Stage of crossing over in prophase I.
Lead Question - 2013
After first meiotic division, the primary oocyte remains arrested in?
a) Diplotene stage
b) Pachytene stage
c) Metaphase
d) Telophase
Explanation: Primary oocytes initiate meiosis during fetal life but arrest in prophase I at the diplotene stage until puberty. Secondary oocyte then arrests at metaphase II until fertilization. Hence, the correct answer is Diplotene stage, the site of first meiotic arrest.
1) Secondary oocyte is arrested at?
a) Diplotene
b) Metaphase I
c) Metaphase II
d) Telophase II
Explanation: After ovulation, the secondary oocyte proceeds to metaphase II, where it arrests until fertilization occurs. This ensures normal chromosomal segregation only after sperm entry. Correct answer is Metaphase II.
2) A 20-year-old woman undergoes ovulation induction. At ovulation, oocyte is arrested in?
a) Prophase I
b) Metaphase I
c) Metaphase II
d) Telophase I
Explanation: At ovulation, the oocyte is a secondary oocyte, arrested in metaphase II. This arrest persists until fertilization by sperm. Correct answer is Metaphase II.
3) Which hormone triggers completion of meiosis I in oocyte?
a) Estrogen
b) LH surge
c) Progesterone
d) FSH
Explanation: The LH surge triggers resumption of meiosis I in the primary oocyte, leading to its completion and formation of secondary oocyte and first polar body. Thus, the correct answer is LH surge.
4) A 28-year-old infertile female shows multiple primary oocytes arrested in diplotene. Likely diagnosis?
a) PCOS
b) Ovarian dysgenesis
c) Premature ovarian failure
d) Aromatase deficiency
Explanation: Arrest of primary oocytes in diplotene persisting without progression is seen in premature ovarian failure or dysgenesis, leading to infertility. Correct answer is Premature ovarian failure.
5) First polar body is extruded at?
a) Before ovulation
b) During ovulation
c) After fertilization
d) During puberty onset
Explanation: The first polar body is extruded at ovulation after meiosis I is completed under the influence of LH surge. Thus, correct answer is During ovulation.
6) A 24-year-old woman presents with infertility. Genetic analysis shows nondisjunction during meiosis I in oocyte. Possible outcome?
a) Turner syndrome
b) Klinefelter syndrome
c) Down syndrome
d) All of the above
Explanation: Nondisjunction during meiosis I of oocyte may lead to aneuploidy, resulting in disorders like Down, Turner, or Klinefelter syndromes. Thus, the correct answer is All of the above.
7) Diplotene arrest in oocytes is maintained by?
a) Estrogen
b) LH
c) Oocyte maturation inhibitor (OMI)
d) Progesterone
Explanation: OMI, secreted by granulosa cells, maintains diplotene arrest in primary oocytes until puberty. LH surge removes this inhibition. Correct answer is Oocyte maturation inhibitor.
8) A 30-year-old patient with infertility is given hCG injection. This mimics which natural hormone action on oocyte maturation?
a) FSH
b) LH
c) Progesterone
d) Prolactin
Explanation: hCG mimics LH surge, inducing resumption of meiosis I and ovulation. Thus, the correct answer is LH.
9) Fertilization completes which phase of meiosis in oocyte?
a) Meiosis I
b) Metaphase I
c) Meiosis II
d) Telophase I
Explanation: Fertilization triggers the completion of meiosis II in the secondary oocyte, leading to formation of a mature ovum and second polar body. Correct answer is Meiosis II.
10) A newborn girl has oocytes arrested in diplotene stage. This condition is?
a) Abnormal
b) Normal physiology
c) PCOS
d) Premature ovarian failure
Explanation: All primary oocytes in a newborn female are normally arrested in diplotene stage of prophase I until puberty. Thus, this is Normal physiology.
Topic: Reproductive Hormones
Subtopic: Androgens
Keyword Definitions:
• Androgens: Male sex hormones responsible for development of male traits.
• Testosterone: Primary androgen secreted by Leydig cells of testes.
• Dihydrotestosterone (DHT): Potent androgen derived from testosterone by 5α-reductase.
• Androstenedione: Weak androgen, precursor for testosterone and estrogen.
• 17α-hydroxyprogesterone: Steroid intermediate in cortisol synthesis, not an androgen.
• Leydig cells: Testicular cells secreting testosterone.
• 5α-reductase: Enzyme converting testosterone into DHT.
Lead Question - 2013
All are androgens except?
a) Testosterone
b) Dihydrotestosterone
c) Androstenedione
d) 17a-hydroxyprogesterone
Explanation: Testosterone, DHT, and androstenedione are androgens that regulate male sexual development. 17α-hydroxyprogesterone, however, is a steroid intermediate in glucocorticoid synthesis and not an androgen. Therefore, the correct answer is 17α-hydroxyprogesterone.
1) Which enzyme converts testosterone to dihydrotestosterone?
a) Aromatase
b) 5α-reductase
c) 17β-HSD
d) Desmolase
Explanation: Testosterone is converted into potent dihydrotestosterone by 5α-reductase enzyme, particularly in prostate, skin, and hair follicles. Inhibition of this enzyme is used in benign prostatic hyperplasia treatment. Correct answer is 5α-reductase.
2) A 28-year-old male presents with infertility. Hormonal analysis shows low testosterone and high LH. Likely pathology?
a) Pituitary adenoma
b) Leydig cell failure
c) 21-hydroxylase deficiency
d) Klinefelter syndrome
Explanation: High LH with low testosterone indicates testicular (Leydig cell) failure, leading to hypogonadism and infertility. This is a form of primary hypogonadism. Correct answer is Leydig cell failure.
3) Main source of androstenedione in females?
a) Adrenal cortex
b) Theca cells of ovary
c) Granulosa cells
d) Corpus luteum
Explanation: Androstenedione in females is mainly produced by adrenal cortex and ovarian theca cells. It acts as a precursor for estrogen synthesis. Correct answer is Adrenal cortex.
4) A 6-year-old boy shows premature pubic hair and acne. Labs: high DHEA-S, normal testosterone. Diagnosis?
a) Central precocious puberty
b) Adrenal tumor
c) Leydig cell tumor
d) Pituitary adenoma
Explanation: High DHEA-S with normal testosterone suggests adrenal source androgen excess, most consistent with adrenal tumor or hyperplasia. Correct answer is Adrenal tumor.
5) Which androgen is most potent at androgen receptor?
a) Testosterone
b) DHEA
c) DHT
d) Androstenedione
Explanation: Dihydrotestosterone (DHT) binds more strongly to androgen receptors than testosterone or androstenedione. It mediates prostate growth, hair pattern, and external genitalia development. Correct answer is DHT.
6) A 25-year-old female with hirsutism has raised 17α-hydroxyprogesterone. Most likely disorder?
a) Polycystic ovary syndrome
b) Androgen-secreting tumor
c) Congenital adrenal hyperplasia
d) Ovarian failure
Explanation: High 17α-hydroxyprogesterone indicates 21-hydroxylase deficiency, a form of congenital adrenal hyperplasia, leading to androgen excess and hirsutism. Correct answer is Congenital adrenal hyperplasia.
7) Which androgen is secreted by adrenal glands?
a) Testosterone
b) DHEA
c) DHT
d) None
Explanation: Adrenal glands secrete weak androgens like DHEA and androstenedione, which can be converted to testosterone in peripheral tissues. Correct answer is DHEA.
8) A 30-year-old man has prostate cancer. Which drug reduces DHT levels?
a) Flutamide
b) Finasteride
c) Ketoconazole
d) Tamoxifen
Explanation: Finasteride inhibits 5α-reductase, blocking conversion of testosterone to DHT, thereby reducing prostate growth. It is used in prostate cancer and BPH. Correct answer is Finasteride.
9) Which androgen is an intermediate in estrogen synthesis?
a) Testosterone
b) DHT
c) Androstenedione
d) DHEA-S
Explanation: Androstenedione is converted to estrone by aromatase, serving as an intermediate in estrogen synthesis. Correct answer is Androstenedione.
10) A newborn girl has ambiguous genitalia. Labs: High 17α-hydroxyprogesterone. Likely diagnosis?
a) Turner syndrome
b) Congenital adrenal hyperplasia
c) PCOS
d) Androgen insensitivity
Explanation: Ambiguous genitalia in a newborn with high 17α-hydroxyprogesterone strongly suggests 21-hydroxylase deficiency, a type of congenital adrenal hyperplasia. Correct answer is Congenital adrenal hyperplasia.
Topic: Adrenal Gland
Subtopic: Hormone Deficiency in Adrenal Atrophy
Keyword Definitions:
• Adrenal Cortex: Outer region of adrenal gland producing cortisol, aldosterone, and androgens.
• Adrenal Atrophy: Shrinkage of adrenal cortex due to prolonged lack of ACTH stimulation.
• Cortisol: Glucocorticoid hormone regulating stress, metabolism, and immunity.
• ACTH: Pituitary hormone stimulating adrenal cortex to release cortisol.
• CRH: Hypothalamic hormone stimulating ACTH secretion.
• MSH: Melanocyte-stimulating hormone, derived from ACTH precursor.
• Addison’s disease: Primary adrenal insufficiency due to cortex damage.
• Cushing’s syndrome: Condition of cortisol excess, often iatrogenic.
Lead Question - 2013
Chronic atrophy of adrenal gland will result in which hormone deficiency?
a) CRH
b) ACTH
c) Cortisol
d) MSH
Explanation: In adrenal atrophy, cortisol production is severely reduced because adrenal cortex cells are destroyed or suppressed. ACTH and CRH may be elevated as feedback response, but hormone loss occurs at the adrenal level. Hence, the main deficiency is cortisol.
1) Which zone of adrenal cortex secretes cortisol?
a) Zona glomerulosa
b) Zona fasciculata
c) Zona reticularis
d) Medulla
Explanation: Cortisol is secreted by the zona fasciculata of the adrenal cortex. Aldosterone is secreted by zona glomerulosa, and androgens by zona reticularis. Correct answer is Zona fasciculata.
2) A 45-year-old male on long-term steroids suddenly stops therapy. Which complication may occur?
a) Hypertension
b) Adrenal crisis
c) Cushing’s syndrome
d) Pheochromocytoma
Explanation: Long-term steroid therapy suppresses ACTH and causes adrenal atrophy. Abrupt withdrawal can precipitate adrenal crisis with hypotension and shock. Correct answer is Adrenal crisis.
3) Which hormone is unaffected in adrenal atrophy?
a) Aldosterone
b) Cortisol
c) Androgens
d) Epinephrine
Explanation: Adrenal medulla (producing epinephrine) is independent of ACTH and remains functional even in adrenal cortex atrophy. Correct answer is Epinephrine.
4) A 30-year-old woman with chronic adrenal insufficiency presents with hyperpigmentation. Which hormone is elevated?
a) Cortisol
b) ACTH
c) Aldosterone
d) Epinephrine
Explanation: In primary adrenal insufficiency, low cortisol leads to increased ACTH secretion. ACTH precursor also generates MSH, leading to hyperpigmentation. Correct answer is ACTH.
5) Which test is used to confirm adrenal insufficiency?
a) Dexamethasone suppression test
b) ACTH stimulation test
c) Insulin tolerance test
d) CRH stimulation test
Explanation: ACTH stimulation test is the gold standard for diagnosing adrenal insufficiency. Failure of cortisol to rise after ACTH injection confirms adrenal dysfunction. Correct answer is ACTH stimulation test.
6) A patient presents with fatigue, hypotension, and weight loss. Labs show low cortisol, high ACTH. Diagnosis?
a) Secondary adrenal insufficiency
b) Addison’s disease
c) Cushing’s disease
d) Hypopituitarism
Explanation: Low cortisol with high ACTH suggests primary adrenal failure (Addison’s disease), as pituitary continues secreting ACTH but adrenals cannot respond. Correct answer is Addison’s disease.
7) Which steroid enzyme deficiency causes salt-wasting crisis?
a) 21-hydroxylase
b) 17-hydroxylase
c) 11β-hydroxylase
d) Aromatase
Explanation: 21-hydroxylase deficiency prevents aldosterone and cortisol synthesis, causing salt-wasting crisis and virilization due to androgen excess. Correct answer is 21-hydroxylase.
8) A patient with long-term adrenal atrophy requires stress dose steroids during surgery. Why?
a) To reduce hypertension
b) To prevent infection
c) To prevent adrenal crisis
d) To reduce ACTH
Explanation: Adrenal atrophy leads to inability to increase cortisol secretion during stress. Extra steroid coverage prevents adrenal crisis. Correct answer is To prevent adrenal crisis.
9) Which hormone regulates aldosterone secretion mainly?
a) ACTH
b) Renin-angiotensin system
c) Cortisol
d) CRH
Explanation: Aldosterone secretion is primarily controlled by the renin-angiotensin-aldosterone system (RAAS) and serum potassium, with ACTH having only minor influence. Correct answer is Renin-angiotensin system.
10) A 50-year-old man has weakness, low sodium, high potassium, and low cortisol. Which other hormone is deficient?
a) Aldosterone
b) ACTH
c) CRH
d) Epinephrine
Explanation: Primary adrenal insufficiency causes loss of both cortisol and aldosterone, leading to hyponatremia and hyperkalemia. Correct answer is Aldosterone.
Topic: Thyroid Gland
Subtopic: Thyroid Hormone Receptor
Keyword Definitions:
• Thyroid Hormones: Include T3 (triiodothyronine) and T4 (thyroxine).
• TSH: Thyroid-stimulating hormone, secreted by anterior pituitary, regulates thyroid hormone release.
• TRH: Thyrotropin-releasing hormone, secreted by hypothalamus, stimulates TSH secretion.
• Thyroid Hormone Receptor: Nuclear receptor binding primarily to T3, regulating gene transcription.
• T4: Prohormone converted to active T3 in peripheral tissues.
• T3: Active thyroid hormone, binds receptors to regulate metabolism and growth.
• Goiter: Thyroid gland enlargement due to various causes.
• Thyrotoxicosis: Clinical syndrome of thyroid hormone excess.
Lead Question - 2013
True about thyroid hormone receptor is?
a) Directly binds to TSH
b) Directly binds to TRH
c) Are surface receptors
d) Causes nuclear transcription after binding with T4
Explanation: Thyroid hormone receptors are nuclear receptors located inside target cells. T3 (not T4 directly) binds strongly to these receptors and regulates gene transcription. TSH and TRH act on cell-surface receptors but not nuclear receptors. Correct answer is Causes nuclear transcription after binding with T4 (via T3).
1) Which thyroid hormone is more active at receptor level?
a) T3
b) T4
c) rT3
d) Thyroglobulin
Explanation: T3 is the biologically active thyroid hormone with higher affinity for nuclear receptors, whereas T4 is a prohormone converted to T3. Reverse T3 (rT3) is inactive. Correct answer is T3.
2) A patient with hypothyroidism is treated with levothyroxine. This drug is?
a) T3
b) T4
c) rT3
d) TRH analogue
Explanation: Levothyroxine is synthetic T4, which is converted in peripheral tissues to T3, the active hormone. It is the standard therapy for hypothyroidism. Correct answer is T4.
3) Which receptor type does TSH act on?
a) Tyrosine kinase receptor
b) G-protein coupled receptor
c) Nuclear receptor
d) Ion channel receptor
Explanation: TSH acts on a G-protein coupled receptor (GPCR) present on thyroid follicular cells, stimulating adenylate cyclase and thyroid hormone synthesis. Correct answer is G-protein coupled receptor.
4) A 30-year-old woman has weight loss, tachycardia, and heat intolerance. Which receptor is overstimulated?
a) TRH receptor
b) TSH receptor
c) Thyroid hormone nuclear receptor
d) Dopamine receptor
Explanation: In hyperthyroidism, nuclear thyroid hormone receptors are overstimulated by excess T3, leading to increased metabolic activity. Correct answer is Thyroid hormone nuclear receptor.
5) Which enzyme converts T4 into T3?
a) Thyroperoxidase
b) Deiodinase
c) Thyroglobulin
d) Tyrosine hydroxylase
Explanation: Peripheral deiodinases convert T4 into T3, the active hormone. Different types (D1, D2) regulate tissue-specific conversion. Correct answer is Deiodinase.
6) A 40-year-old male with Graves’ disease has antibodies acting on which receptor?
a) TSH receptor
b) TRH receptor
c) Nuclear receptor
d) Dopamine receptor
Explanation: Graves’ disease is caused by thyroid-stimulating immunoglobulins binding to TSH receptors on thyroid cells, stimulating excess hormone release. Correct answer is TSH receptor.
7) Which thyroid hormone crosses the cell membrane more readily?
a) T3
b) T4
c) Both equally
d) None
Explanation: T3 is more lipophilic and readily enters cells to bind nuclear receptors, exerting biological effects. Correct answer is T3.
8) A newborn with congenital hypothyroidism has developmental delay. Which mechanism is responsible?
a) Deficient TSH receptor binding
b) Deficient TRH receptor binding
c) Absent nuclear receptor activation
d) Excess dopamine effect
Explanation: Lack of thyroid hormone in early life leads to reduced activation of nuclear thyroid receptors, impairing growth and brain development. Correct answer is Absent nuclear receptor activation.
9) Which drug inhibits peripheral conversion of T4 to T3?
a) Propylthiouracil
b) Methimazole
c) Levothyroxine
d) Thyroglobulin
Explanation: Propylthiouracil (PTU) inhibits both thyroid peroxidase and peripheral conversion of T4 to T3. Methimazole inhibits only thyroid peroxidase. Correct answer is Propylthiouracil.
10) A patient with pituitary adenoma secreting excess TSH will have?
a) Low T3, Low T4
b) High T3, High T4
c) Normal T3, Low T4
d) Low T3, High T4
Explanation: In TSH-secreting pituitary adenoma, overstimulation of thyroid gland leads to high T3 and T4, producing thyrotoxicosis. Correct answer is High T3, High T4.
Topic: Male Reproductive Hormones
Subtopic: Testosterone Regulation
Keyword Definitions:
• Testosterone – Primary male sex hormone produced by Leydig cells.
• FSH – Follicle-stimulating hormone, regulates spermatogenesis.
• LH – Luteinizing hormone, stimulates Leydig cells to produce testosterone.
• Hypoandrogenism – Deficiency of androgens leading to reduced male sexual function.
• Spermatogenesis – Process of sperm cell development in seminiferous tubules.
• Negative Feedback – Mechanism by which testosterone suppresses LH/FSH release.
Lead Question - 2013
After injecting testosterone in a hypoandrogenic male, which of the following occurs ?
a) Decreased FSH secretion
b) Decreased LH secretion
c) Increased spermatogenesis
d) None of the above
Explanation: Testosterone supplementation exerts negative feedback on the hypothalamic-pituitary axis. This reduces LH secretion significantly as Leydig cells no longer need stimulation. FSH reduction may also occur, but LH suppression is most prominent. Thus, the correct answer is Decreased LH secretion (option b).
1) Which enzyme converts testosterone to dihydrotestosterone (DHT)?
a) Aromatase
b) 5-alpha reductase
c) 17-beta hydroxylase
d) 21-hydroxylase
Explanation: Testosterone is converted to dihydrotestosterone (DHT) by the enzyme 5-alpha reductase. DHT is a more potent androgen responsible for external genitalia development and male pattern baldness. Thus, the correct answer is 5-alpha reductase (option b).
2) A 25-year-old male has infertility with low sperm count and high FSH, normal testosterone. Which is most likely?
a) Klinefelter syndrome
b) Sertoli cell-only syndrome
c) Hypogonadotropic hypogonadism
d) Leydig cell tumor
Explanation: Elevated FSH with normal testosterone suggests defective Sertoli cell function while Leydig cells are intact. This is typical of Sertoli cell-only syndrome, leading to infertility despite normal androgen levels. Thus, the correct answer is Sertoli cell-only syndrome (option b).
3) Which hormone stimulates Leydig cells to produce testosterone?
a) FSH
b) LH
c) Prolactin
d) ACTH
Explanation: Luteinizing hormone (LH), secreted from the anterior pituitary, binds to receptors on Leydig cells of testes and stimulates testosterone production. FSH instead stimulates Sertoli cells. Therefore, the correct answer is LH (option b).
4) A 40-year-old man on long-term anabolic steroids develops testicular atrophy. Why?
a) Increased FSH
b) Increased LH
c) Suppression of gonadotropins
d) Overproduction of GnRH
Explanation: Exogenous anabolic steroids increase testosterone levels, which suppress LH and FSH through negative feedback. This suppression reduces testicular stimulation, causing atrophy. Thus, the correct answer is Suppression of gonadotropins (option c).
5) In males, inhibin is secreted by:
a) Leydig cells
b) Sertoli cells
c) Spermatogonia
d) Prostate
Explanation: Sertoli cells within the seminiferous tubules secrete inhibin, which provides negative feedback specifically on FSH secretion. Leydig cells secrete testosterone instead. Hence, the correct answer is Sertoli cells (option b).
6) A 19-year-old boy presents with gynecomastia and small firm testes. Karyotype: 47,XXY. Which is true?
a) Low testosterone, high FSH, high LH
b) High testosterone, low FSH
c) High testosterone, high LH
d) Low FSH, low LH
Explanation: Klinefelter syndrome features primary testicular failure, causing low testosterone and loss of negative feedback. Consequently, FSH and LH are elevated. Thus, the correct answer is Low testosterone, high FSH, high LH (option a).
7) Which of the following is NOT an effect of testosterone?
a) Growth of facial hair
b) Increased muscle mass
c) Development of breast tissue
d) Increased libido
Explanation: Testosterone is responsible for male secondary sexual characteristics such as facial hair, muscle mass, and libido. Gynecomastia or breast tissue development is not a direct effect; it may occur due to aromatization of testosterone to estrogen. Thus, the correct answer is Development of breast tissue (option c).
8) A 28-year-old man presents with infertility. Labs: low LH, low FSH, low testosterone. Diagnosis?
a) Primary hypogonadism
b) Secondary hypogonadism
c) Androgen resistance
d) Sertoli cell failure
Explanation: Simultaneous low LH, FSH, and testosterone indicate pituitary or hypothalamic dysfunction, i.e., secondary hypogonadism. Primary testicular failure would cause elevated gonadotropins. Hence, the correct answer is Secondary hypogonadism (option b).
9) Testosterone is mainly metabolized in:
a) Kidneys
b) Liver
c) Adrenal glands
d) Testes
Explanation: Testosterone is primarily metabolized in the liver, where it is converted into inactive metabolites and then excreted in urine. Hence, the correct answer is Liver (option b).
10) A 16-year-old boy has delayed puberty, low testosterone, anosmia. Which syndrome is suspected?
a) Turner syndrome
b) Kallmann syndrome
c) Androgen insensitivity syndrome
d) Noonan syndrome
Explanation: Kallmann syndrome is characterized by hypogonadotropic hypogonadism with anosmia due to failure of GnRH neurons to migrate. This causes low testosterone and absent puberty. Thus, the correct answer is Kallmann syndrome (option b).
11) Which hormone stimulates spermatogenesis directly via Sertoli cells?
a) FSH
b) LH
c) Testosterone
d) Prolactin
Explanation: FSH acts directly on Sertoli cells to promote spermatogenesis, whereas testosterone from Leydig cells provides paracrine support. Thus, the correct answer is FSH (option a).
Topic: Bone Physiology
Subtopic: Hormonal Regulation of Bone Growth
Keyword Definitions:
• Chondrocyte – Cartilage cell responsible for matrix formation.
• Osteogenic cells – Precursor bone cells that differentiate into osteoblasts.
• IGF-1 – Insulin-like growth factor, stimulated by GH, promotes bone and cartilage growth.
• Growth Hormone – Pituitary hormone that indirectly promotes bone growth via IGF-1.
• Thyroxine – Thyroid hormone, essential for normal bone development.
• Bone Remodeling – Continuous process of bone resorption and new bone formation.
Lead Question - 2013
Conversion of chondrocyte into osteogenic cells is caused by ?
a) Insulin
b) IGF-1
c) Growth hormone
d) Thyroxine
Explanation: Growth hormone stimulates the liver to produce IGF-1, which acts on cartilage cells (chondrocytes), inducing their differentiation into osteogenic cells and promoting endochondral ossification. This is crucial in longitudinal bone growth. Therefore, the correct answer is IGF-1 (option b).
1) Which hormone directly stimulates osteoclast activity?
a) Calcitonin
b) Parathyroid hormone
c) Vitamin D
d) Estrogen
Explanation: Parathyroid hormone stimulates osteoclast activity indirectly through osteoblast signaling, leading to increased bone resorption and calcium release. Calcitonin instead inhibits osteoclasts. Hence, the correct answer is Parathyroid hormone (option b).
2) A 12-year-old boy with short stature has low IGF-1 levels despite normal GH. Likely cause?
a) Liver dysfunction
b) Pituitary adenoma
c) Hypothyroidism
d) Adrenal insufficiency
Explanation: IGF-1 is produced primarily in the liver under GH influence. If GH levels are normal but IGF-1 is low, liver dysfunction is the likely cause, impairing growth signaling. Thus, the correct answer is Liver dysfunction (option a).
3) Which hormone primarily stimulates osteoblast activity?
a) Estrogen
b) Testosterone
c) Vitamin D
d) PTH
Explanation: Vitamin D promotes mineralization and directly enhances osteoblast activity by increasing calcium and phosphate absorption and facilitating bone formation. Thus, the correct answer is Vitamin D (option c).
4) A child with rickets has bone deformities and low calcium. Which deficiency is most likely?
a) Vitamin A
b) Vitamin D
c) Vitamin K
d) Vitamin C
Explanation: Rickets in children results from vitamin D deficiency, impairing calcium and phosphate absorption, causing defective mineralization of bone. Hence, the correct answer is Vitamin D (option b).
5) Which bone cells are responsible for bone resorption?
a) Osteoblasts
b) Osteocytes
c) Osteoclasts
d) Osteogenic cells
Explanation: Osteoclasts are multinucleated cells derived from monocytes responsible for bone resorption. Osteoblasts build new bone, osteocytes maintain bone, and osteogenic cells are progenitors. Thus, the correct answer is Osteoclasts (option c).
6) A 16-year-old with delayed puberty shows poor bone growth. Lab: low thyroxine. Likely effect on bone?
a) Enhanced bone elongation
b) Impaired endochondral ossification
c) Excessive bone resorption
d) Increased osteoclast activity
Explanation: Thyroxine is essential for normal growth and maturation of bone. Deficiency causes impaired endochondral ossification, leading to stunted growth and delayed skeletal maturation. Thus, the correct answer is Impaired endochondral ossification (option b).
7) Which hormone inhibits bone resorption?
a) PTH
b) Calcitonin
c) Cortisol
d) GH
Explanation: Calcitonin, secreted from thyroid C-cells, inhibits osteoclast-mediated bone resorption, lowering serum calcium. Thus, the correct answer is Calcitonin (option b).
8) A patient on long-term glucocorticoids develops osteoporosis. Mechanism?
a) Increased osteoblast function
b) Reduced osteoclast function
c) Inhibition of bone formation
d) Increased calcitonin secretion
Explanation: Glucocorticoids inhibit osteoblast differentiation and increase bone resorption, leading to osteoporosis over time. Thus, the correct answer is Inhibition of bone formation (option c).
9) Which bone structure senses mechanical stress and regulates remodeling?
a) Osteoblasts
b) Osteocytes
c) Osteoclasts
d) Chondrocytes
Explanation: Osteocytes, embedded in bone matrix, sense mechanical stress and signal osteoblasts and osteoclasts to regulate remodeling. Thus, the correct answer is Osteocytes (option b).
10) A child with pituitary gigantism has tall stature due to?
a) Excess cortisol
b) Excess GH before epiphyseal closure
c) Vitamin D deficiency
d) Early puberty
Explanation: Gigantism occurs when excess GH is secreted before epiphyseal plate closure, leading to increased IGF-1 mediated bone growth and extreme height. Thus, the correct answer is Excess GH before epiphyseal closure (option b).
11) Which process replaces cartilage with bone during growth?
a) Intramembranous ossification
b) Endochondral ossification
c) Bone resorption
d) Bone remodeling
Explanation: Endochondral ossification is the process by which cartilage is replaced by bone, essential in long bone development. Intramembranous ossification occurs in flat bones. Thus, the correct answer is Endochondral ossification (option b).
Chapter: Reproductive Physiology
Topic: Breast Development
Subtopic: Hormonal Control of Mammary Glands
Keyword Definitions:
• Lactiferous ducts – Channels that carry milk from lobules to the nipple.
• Estrogen – Hormone responsible for ductal proliferation in breast tissue.
• Progesterone – Promotes lobuloalveolar development of mammary glands.
• Prolactin – Hormone stimulating milk secretion postpartum.
• Oxytocin – Causes milk ejection via myoepithelial contraction.
• LH & FSH – Pituitary gonadotropins regulating ovarian hormones that influence breast growth.
Lead Question - 2013
In breast lactiferous ducts are formed under the influence of which hormone?
a) Estrogen
b) Progesterone
c) LH
d) FSH
Explanation: Estrogen is the key hormone responsible for ductal growth and elongation of lactiferous ducts in the breast, particularly during puberty. Progesterone complements by stimulating alveolar and lobular development. LH and FSH regulate ovarian hormones indirectly. Therefore, the correct answer is Estrogen (option a).
1) Which hormone is mainly responsible for alveolar development of the breast?
a) Estrogen
b) Progesterone
c) Prolactin
d) Oxytocin
Explanation: Progesterone stimulates the lobuloalveolar system, preparing the breast for lactation. Estrogen primarily drives ductal development. Thus, alveolar development is under the influence of Progesterone (option b).
2) A lactating mother is unable to eject milk despite adequate production. Which hormone is deficient?
a) Estrogen
b) Progesterone
c) Oxytocin
d) Prolactin
Explanation: Oxytocin stimulates contraction of myoepithelial cells around alveoli, leading to milk ejection. Prolactin maintains milk production. Failure of ejection indicates Oxytocin deficiency (option c).
3) Which hormone maintains milk production during lactation?
a) Estrogen
b) Prolactin
c) Oxytocin
d) Progesterone
Explanation: Prolactin from the anterior pituitary maintains continuous milk synthesis postpartum. Oxytocin facilitates let-down, not production. Thus, the correct answer is Prolactin (option b).
4) A woman develops galactorrhea with amenorrhea. Likely hormone excess?
a) Prolactin
b) Estrogen
c) Progesterone
d) Oxytocin
Explanation: Galactorrhea with menstrual disturbances is classic of hyperprolactinemia, often due to pituitary adenoma. Thus, the correct answer is Prolactin (option a).
5) Which hormone inhibits lactation during pregnancy?
a) Estrogen and Progesterone
b) Prolactin
c) Oxytocin
d) Cortisol
Explanation: High estrogen and progesterone levels in pregnancy inhibit milk secretion despite high prolactin. After delivery, their fall allows prolactin to initiate lactation. Thus, the correct answer is Estrogen and Progesterone (option a).
6) A woman 3 days postpartum has engorged breasts with no milk secretion. Which hormone is insufficient?
a) Prolactin
b) Oxytocin
c) Estrogen
d) Progesterone
Explanation: Prolactin is required for milk synthesis in alveolar cells. Its deficiency leads to poor secretion despite breast engorgement. Thus, the correct answer is Prolactin (option a).
7) Which hormone increases during suckling to facilitate milk ejection?
a) Estrogen
b) Progesterone
c) Prolactin
d) Oxytocin
Explanation: Suckling reflex stimulates hypothalamus to release oxytocin from the posterior pituitary, which contracts myoepithelial cells for milk let-down. Hence, the answer is Oxytocin (option d).
8) A non-lactating woman with bilateral galactorrhea and visual disturbance likely has?
a) Hypothyroidism
b) Pituitary prolactinoma
c) Cushing’s syndrome
d) Addison’s disease
Explanation: Visual disturbances with galactorrhea suggest a pituitary mass compressing optic chiasma, most often prolactinoma. Thus, the correct answer is Pituitary prolactinoma (option b).
9) Which hormone is essential for breast ductal proliferation during puberty?
a) Estrogen
b) Progesterone
c) LH
d) FSH
Explanation: Estrogen stimulates ductal proliferation in breast tissue during puberty. Progesterone complements with alveolar development later. Thus, the answer is Estrogen (option a).
10) In lactation, which hormone prevents ovulation by suppressing GnRH?
a) Estrogen
b) Prolactin
c) Oxytocin
d) Progesterone
Explanation: Prolactin inhibits hypothalamic GnRH release, suppressing LH and FSH secretion, thereby preventing ovulation during lactation (lactational amenorrhea). Thus, the correct answer is Prolactin (option b).
11) A mother with Sheehan’s syndrome fails to lactate postpartum. Which hormone deficiency is responsible?
a) Estrogen
b) Prolactin
c) Oxytocin
d) Progesterone
Explanation: Sheehan’s syndrome is postpartum pituitary necrosis leading to loss of anterior pituitary hormones. Absence of prolactin prevents initiation of lactation. Thus, the correct answer is Prolactin (option b).
Chapter: Embryology
Topic: Fertilization and Implantation
Subtopic: Time of Implantation
Keyword Definitions:
• Fertilization: Fusion of sperm and ovum forming a zygote.
• Implantation: Process where blastocyst embeds into the endometrium.
• Blastocyst: Early embryonic stage consisting of inner cell mass and trophoblast.
• Endometrium: Uterine lining prepared for embryo implantation.
• Trophoblast: Outer cell layer of blastocyst involved in implantation.
• Luteal phase: Phase of menstrual cycle dominated by progesterone.
• hCG: Hormone secreted by trophoblast to support pregnancy.
• Zona pellucida: Glycoprotein covering around ovum preventing polyspermy.
• Morula: Solid ball of blastomeres formed before blastocyst stage.
• Decidua: Endometrium during pregnancy responding to implantation.
Lead Question - 2013
Implantation occurs after how many days of fertilization?
a) 3-5 days
b) 5-7 days
c) 7-9 days
d) > 14 days
Explanation: Implantation occurs typically on the 6th or 7th day after fertilization, when the blastocyst penetrates the endometrium. Fertilization occurs in the ampulla, cleavage forms morula, which develops into a blastocyst by day 4-5, and implantation begins by day 6-7. Correct answer: 7-9 days (c).
1) Cleavage of zygote results in formation of:
a) Blastocyst
b) Morula
c) Trophoblast
d) Decidua
Explanation: Cleavage is the rapid mitotic division of zygote forming a morula around day 3. The morula later develops into a blastocyst. This process is essential for implantation. Correct answer: Morula (b).
2) Clinical case: A woman with luteal phase defect may have recurrent implantation failure due to deficiency of:
a) Estrogen
b) Progesterone
c) LH
d) FSH
Explanation: Progesterone secreted by corpus luteum maintains endometrium. In luteal phase defect, low progesterone leads to implantation failure and infertility. Treatment involves progesterone supplementation. Correct answer: Progesterone (b).
3) Zona pellucida prevents:
a) Cleavage
b) Polyspermy
c) Fertilization
d) Ovulation
Explanation: Zona pellucida is a glycoprotein coat around the ovum that blocks multiple sperm entry after fertilization by cortical reaction. This ensures normal chromosomal complement. Correct answer: Polyspermy (b).
4) Clinical case: A patient with ectopic pregnancy most commonly shows implantation at:
a) Ampulla
b) Isthmus
c) Cervix
d) Ovary
Explanation: Most ectopic pregnancies occur in the fallopian tube, especially the ampullary region. This abnormal implantation is life-threatening and requires urgent management. Correct answer: Ampulla (a).
5) Hormone responsible for endometrial preparation for implantation:
a) Progesterone
b) Estrogen
c) LH
d) Prolactin
Explanation: Progesterone secreted by corpus luteum converts proliferative endometrium into secretory endometrium, suitable for implantation. Estrogen only stimulates proliferation but progesterone maintains pregnancy. Correct answer: Progesterone (a).
6) Clinical case: A woman develops vaginal bleeding 8 days post-ovulation. This corresponds to:
a) Follicular phase
b) Ovulatory phase
c) Implantation bleeding
d) Menstrual bleeding
Explanation: Implantation bleeding may occur around 7–9 days after ovulation, due to invasion of blastocyst into endometrium and disruption of blood vessels. Correct answer: Implantation bleeding (c).
7) Trophoblast differentiates into:
a) Cytotrophoblast and syncytiotrophoblast
b) Epiblast and hypoblast
c) Morula and blastocyst
d) Decidua and chorion
Explanation: Trophoblast cells of blastocyst differentiate into cytotrophoblast and syncytiotrophoblast, which play roles in implantation and hormone secretion (hCG). Correct answer: Cytotrophoblast and syncytiotrophoblast (a).
8) Clinical case: hCG is detected in maternal blood earliest by:
a) 1 day post-fertilization
b) 4 days post-fertilization
c) 8-9 days post-fertilization
d) 20 days post-fertilization
Explanation: Syncytiotrophoblast secretes hCG once implantation begins, which can be detected in maternal blood about 8-9 days after fertilization. Correct answer: 8-9 days (c).
9) The decidua basalis contributes to formation of:
a) Chorionic villi
b) Placenta
c) Amnion
d) Yolk sac
Explanation: The decidua basalis is the part of maternal endometrium directly beneath the implanted blastocyst. It fuses with chorionic villi to form the placenta. Correct answer: Placenta (b).
10) Clinical case: A woman on day 21 of her menstrual cycle shows endometrium with coiled glands and glycogen. This indicates:
a) Follicular phase
b) Proliferative phase
c) Secretory phase
d) Menstrual phase
Explanation: On day 21, progesterone action makes the endometrium secretory, preparing for implantation. Glands are coiled and glycogen-rich. Correct answer: Secretory phase (c).
Chapter: Reproductive Physiology
Topic: Spermatogenesis
Subtopic: Spermiogenesis
Keyword Definitions:
• Spermatogenesis: Process of sperm production from spermatogonia.
• Spermiogenesis: Final stage where spermatids transform into spermatozoa.
• Spermatogonia: Diploid stem cells in seminiferous tubules.
• Primary spermatocyte: Cell undergoing meiosis I.
• Secondary spermatocyte: Product of meiosis I, haploid cells.
• Spermatid: Haploid, immature sperm precursor cell.
• Spermatozoa: Mature motile male gametes.
• Sertoli cells: Support spermatogenesis and secrete inhibin.
• Leydig cells: Secrete testosterone under LH stimulation.
• Acrosome: Cap-like vesicle in sperm, helps penetration of ovum.
Lead Question - 2013
Spermiogenesis refers to ?
a) Formation of spermatazoa from spermatogonia
b) Formation of spermatazoa from spermatids
c) Formation of spermatids from spermatocytes
d) Formation of secondary spermatocytes from primary spermatocytes
Explanation: Spermiogenesis is the final phase of spermatogenesis, in which haploid spermatids undergo morphological changes to form spermatozoa. Changes include acrosome formation, condensation of nucleus, development of flagellum, and shedding of cytoplasm. This transformation does not involve cell division. Correct answer: b) Formation of spermatozoa from spermatids.
1) Which hormone stimulates Leydig cells to produce testosterone?
a) FSH
b) LH
c) Prolactin
d) Inhibin
Explanation: LH (Luteinizing Hormone) stimulates Leydig cells in the testes to secrete testosterone, which is essential for spermatogenesis and development of male secondary sexual characters. FSH stimulates Sertoli cells. Correct answer: b) LH.
2) Clinical case: A man with infertility has decreased sperm count but normal testosterone. Likely defect is in:
a) Leydig cells
b) Sertoli cells
c) Hypothalamus
d) Adrenal cortex
Explanation: Sertoli cells nourish spermatids, regulate spermiogenesis, and secrete inhibin. Infertility with normal testosterone suggests Sertoli cell dysfunction. Correct answer: b) Sertoli cells.
3) Acrosome of sperm is derived from:
a) Nucleus
b) Mitochondria
c) Golgi apparatus
d) Rough ER
Explanation: The acrosome is a cap-like structure covering the anterior part of the sperm head. It originates from the Golgi apparatus and contains enzymes like hyaluronidase to help penetration of ovum. Correct answer: c) Golgi apparatus.
4) Clinical case: A patient with pituitary adenoma shows low FSH but normal LH. Which function will be most affected?
a) Testosterone secretion
b) Spermatogenesis
c) Secondary sex character development
d) Libido
Explanation: FSH acts on Sertoli cells to support spermatogenesis. Low FSH impairs spermatogenesis despite normal testosterone. Correct answer: b) Spermatogenesis.
5) The mitochondrial sheath of sperm is located in:
a) Head
b) Middle piece
c) Tail
d) Acrosome
Explanation: Mitochondria form a spiral sheath around the middle piece of sperm, providing ATP for motility. Correct answer: b) Middle piece.
6) Clinical case: A man with mutation in dynein arms of sperm shows infertility due to:
a) Acrosomal defect
b) Lack of motility
c) Defective binding to ovum
d) Spermatid arrest
Explanation: Dynein arms are required for flagellar movement. Their absence causes immotile sperm, leading to infertility. This condition is seen in Kartagener’s syndrome. Correct answer: b) Lack of motility.
7) Which cells form the blood-testis barrier?
a) Leydig cells
b) Sertoli cells
c) Spermatogonia
d) Myoid cells
Explanation: Sertoli cells are connected by tight junctions that form the blood-testis barrier, protecting developing spermatogenic cells from autoimmune attack. Correct answer: b) Sertoli cells.
8) Clinical case: A male undergoing chemotherapy develops azoospermia. Which cell type is most susceptible?
a) Spermatogonia
b) Spermatids
c) Sertoli cells
d) Leydig cells
Explanation: Spermatogonia are highly mitotically active, making them most sensitive to chemotherapy and radiation. Their destruction leads to azoospermia. Correct answer: a) Spermatogonia.
9) During spermiogenesis, excess cytoplasm is shed as:
a) Acrosomal cap
b) Cytoplasmic droplet
c) Residual body
d) Sertoli vesicle
Explanation: Spermiogenesis involves elimination of excess cytoplasm, which is shed as residual bodies that are phagocytosed by Sertoli cells. Correct answer: c) Residual body.
10) Clinical case: A male presents with failure of fertilization despite normal sperm count and motility. Likely cause is defective:
a) Acrosome reaction
b) Mitochondria
c) DNA integrity
d) Sertoli cells
Explanation: Fertilization requires acrosome reaction, which releases enzymes to penetrate zona pellucida. Defective acrosome reaction leads to infertility. Correct answer: a) Acrosome reaction.