Nokea
Which cranial nerve is not involved in acromegaly?
- A. VIII
- B. III, IV, VI
- C. V
- D. Il
Correct Answer: A
Rationale: Acromegaly is a disorder caused by the overproduction of growth hormone in adulthood, usually due to a pituitary tumor. The cranial nerves that may be affected in acromegaly are Cranial Nerves III, IV, VI (oculomotor, trochlear, abducens) due to compression of the optic chiasm by the expanding tumor. Cranial Nerve V (trigeminal nerve) may also be affected given its close proximity to the pituitary gland. However, Cranial Nerve VIII (vestibulocochlear nerve) is not typically involved in acromegaly.
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Thyroid-stimulating hormone (TSH):
- A. is synthesized in parafollicular cells
- B. is a template for thyroid hormone biosynthesis.
- C. is derived from iodinated tyrosine residues.
- D. secretion is inhibited by TRH from the hypothalamus.
Correct Answer: D
Rationale: Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). TSH secretion is regulated by the hypothalamus via the release of thyrotropin-releasing hormone (TRH). TRH acts on the anterior pituitary gland to stimulate the production and release of TSH. Therefore, TSH secretion is indeed inhibited by TRH, not stimulated as in the other options.
Which one of the following statements is true regarding the prevalence of acromegaly?
- A. Acromegaly affects a similar number of men and women
- B. Acromegaly affects twice as many women than men
- C. Acromegaly affects twice as many men than it does women
Correct Answer: C
Rationale: Acromegaly is a rare hormonal disorder where excess growth hormone is produced, leading to the enlargement of bones and tissues. The prevalence of acromegaly is higher in men compared to women, with a ratio of about two men affected for every woman. This gender difference is believed to be due to the impact of sex hormones on the development and progression of the condition. While acromegaly can affect both men and women, men are more commonly diagnosed with the disorder.
Commonest cause of 'ambiguous genitalia' in newborn is:
- A. Congenital adrenal hyperplasia
- B. True hermaphroditism
- C. Testicular ferminisation syndrome
- D. Pseudo-hermaphroditism
Correct Answer: A
Rationale: Congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia in newborns. This condition is due to a deficiency of enzymes in the adrenal gland that are necessary for the production of cortisol. As a result, the body produces excess androgens (masculinizing hormones), leading to abnormal genital development in females. The external genitalia may appear ambiguous, with features of both male and female genitalia. This condition can be detected through newborn screening and confirmed through further hormonal and genetic testing. Treatment involves hormone replacement therapy to normalize hormone levels and surgery may be required to reconstruct the genitalia.
In males which hormone stimulates Leydig cells to produce testosterone?
- A. Follicle stimulating hormone (FSH)
- B. Luteinizing hormone (LH)
- C. hormone
- D. insipidus
Correct Answer: B
Rationale: In males, Leydig cells in the testes are stimulated to produce testosterone by luteinizing hormone (LH). LH is produced by the anterior pituitary gland and acts on the Leydig cells to promote the synthesis and release of testosterone. This hormone plays a crucial role in male reproductive function and the development of masculine characteristics. Follicle stimulating hormone (FSH) plays a role in spermatogenesis in males but does not directly stimulate Leydig cells to produce testosterone.
Oxytocin and antidiuretic hormone (ADH; vasopressin) are:
- A. complex steroids.
- B. synthesized and stored in the posterior pituitary.
- C. released from the anterior pituitary where blood is hypotonic.
- D. synthesized in the hypothalamus and released from the posterior pituitary.
Correct Answer: D
Rationale: Oxytocin and antidiuretic hormone (ADH; vasopressin) are both synthesized in the hypothalamus, specifically in the supraoptic and paraventricular nuclei. After synthesis, they are transported along axons to the posterior pituitary where they are stored until they are released into the bloodstream when needed. This is why they are released from the posterior pituitary, not the anterior pituitary. These hormones have different functions in the body, with oxytocin being involved in labor and breastfeeding, while ADH plays a role in regulating water balance and blood pressure.