Nokea
"Pseudo-Cushing's syndrome' may be found in all except:
- A. Myxoedema
- B. Chronic alcoholism
- C. Obesity
- D. Depression
Correct Answer: A
Rationale: Pseudo-Cushing's syndrome is a condition that mimics the symptoms of Cushing's syndrome but is not actually caused by excess cortisol production by the adrenal glands. It can be caused by various conditions such as chronic alcoholism, obesity, depression, and certain medications. However, myxoedema (also known as severe hypothyroidism) is not typically associated with pseudo-Cushing's syndrome. Myxoedema is characterized by low thyroid hormone levels, which would not lead to the symptoms of pseudo-Cushing's syndrome.
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Commonest enzymatic defect for development of congenital adrenal hyperplasia is:
- A. C-21 hydroxylase deficiency
- B. 3b dehydrogenase deficiency
- C. C-11 hydroxylase deficiency
- D. C-17 hydroxylase deficiency
Correct Answer: A
Rationale: C-21 hydroxylase deficiency is the most common enzymatic defect leading to the development of congenital adrenal hyperplasia (CAH). This enzyme is necessary for the synthesis of cortisol and aldosterone in the adrenal glands. When there is a deficiency in C-21 hydroxylase, the pathway is shifted towards the production of androgens instead of cortisol and aldosterone, leading to excess androgen production. This results in the characteristic features of CAH, such as ambiguous genitalia in females and virilization in both males and females. Other enzyme deficiencies listed in the choices can also lead to different types of CAH but are less common compared to C-21 hydroxylase deficiency.
Anti-diuretic hormone secretion is:
- A. increased during stress.
- B. reduced during hemorrhage.
- C. reduced by increased blood osmolality.
- D. increased by alcohol.
Correct Answer: B
Rationale: Anti-diuretic hormone (ADH), also known as vasopressin, is a hormone released by the pituitary gland in response to changes in blood osmolality, blood volume, and blood pressure. During hemorrhage (significant blood loss), the body experiences a decrease in blood volume and blood pressure. In response to this decrease in blood volume, ADH secretion is increased to help the body retain water and maintain blood pressure levels. Therefore, it is incorrect to say that ADH secretion is reduced during hemorrhage.
Neurological features of myxoedema include all of the following except:
- A. Delayed relaxation of ankle jerk
- B. Cerebellar ataxia
- C. Hypertonia
- D. Bradylalia
Correct Answer: B
Rationale: Myxoedema refers to severe hypothyroidism which can lead to neurological manifestations. The correct features associated with myxoedema include delayed relaxation of ankle jerk (Choice A), hypertonia (Choice C), and bradylalia (Choice D). Cerebellar ataxia, which involves incoordination and balance issues due to dysfunction of the cerebellum, is not a typical neurological feature seen in myxoedema.
Aldosterone:
- A. is synthesized in the zona fasciculata.
- B. is deficient in Conn's syndrome.
- C. is independent of ACTH.
- D. is suppressed by elevated potassium.
Correct Answer: D
Rationale: Aldosterone is a hormone produced in the zona glomerulosa of the adrenal cortex, not the zona fasciculata (Choice A is incorrect). Conn's syndrome, also known as primary hyperaldosteronism, is characterized by excess aldosterone secretion, not a deficiency (Choice B is incorrect). Aldosterone production is under the control of the renin-angiotensin-aldosterone system, which is stimulated by factors such as low blood pressure, low blood volume, and high potassium levels. Elevated potassium in the blood directly suppresses aldosterone production by the adrenal glands, serving as a negative feedback mechanism to maintain electrolyte balance (Choice D is correct). The synthesis of aldosterone also requires cholesterol as the precursor, rather than pregnenolone (Choice E is incorrect). Lastly, aldosterone production is regulated in part by ACTH (adrenocorticotropic hormone), as it can enhance the effects of
Thyroid hormones (T3 and T4):
- A. increase metabolic rate.
- B. are hydrophilic as they are made from amino acids.
- C. contain iron atoms in ferrous form.
- D. stimulate the secretion of thyroid-stimulating hormone (TSH; thyrotropin).
Correct Answer: A
Rationale: Thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine), play a crucial role in regulating metabolism in the body. They are responsible for increasing the metabolic rate of cells by influencing the production of proteins and controlling how the body uses energy. This increase in metabolic rate results in processes such as increased heart rate, enhanced nutrient breakdown, and higher body temperature. Thus, option A, "increase metabolic rate," is the correct statement regarding thyroid hormones (T3 and T4).