Nokea
Phaeochromocytoma may be associated with following anomalies except:
- A. Neurofibromatosis
- B. Medullary carcinoma of thyroid
- C. Hyperparathyroidism
- D. Addison's disease
Correct Answer: A
Rationale: Phaeochromocytoma may be associated with Medullary carcinoma of thyroid, Hyperparathyroidism, and Addison's disease as part of MEN Syndrome (Multiple Endocrine Neoplasia) Type 2. However, it is not typically associated with Neurofibromatosis. Neurofibromatosis is associated with the development of benign tumors of nerve tissue and is not directly linked to the presence of Phaeochromocytoma.
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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
Hormones are:
- A. biologically inert by themselves.
- B. used as an energy source
- C. incorporated as a structural moiety into another molecule
- D. always stored in secretory granules
Correct Answer: C
Rationale: Hormones are chemical messengers that are produced by various glands in the body and released into the bloodstream to signal and regulate the activity of specific target cells. Unlike energy sources that can be metabolized for energy production (like carbohydrates and fats), hormones are not typically used as an energy source themselves (Choice B). Hormones are typically not biologically inert by themselves (Choice A), as they have specific functions in regulating various physiological processes in the body. While some hormones may be stored in secretory granules before release, not all hormones are stored in this manner (Choice D). Additionally, hormones are not always released by exocytosis (Choice E), as some hormones can also be released through other mechanisms such as diffusion. The correct choice, therefore, is C: hormones are incorporated as a structural moiety into another molecule, as they bind to specific receptors on target cells to elicit a cellular response and regulate physiological functions.
Which age group does acromegaly most commonly affect?
- A. 30-50 years
- B. 10-25 years
- C. 55-70 years
- D. 25-40 years
Correct Answer: A
Rationale: Acromegaly most commonly affects individuals in the age group of 30-50 years. This condition is typically diagnosed in adults between these ages. Acromegaly is often caused by the overproduction of growth hormone in adults, which leads to excessive bone growth and tissue expansion. While acromegaly can develop at any age, it is more commonly seen in adults within the 30-50 age range.
All of the following are features of Conn's syndrome except:
- A. Alkalosis
- B. Hyperkalemia
- C. Muscle cramps
- D. Severe systemic hypertension
Correct Answer: B
Rationale: Conn's syndrome, also known as primary hyperaldosteronism, is characterized by excess production of aldosterone by the adrenal glands. This leads to increased sodium retention and potassium excretion in the kidneys. As a result, patients with Conn's syndrome typically present with hypokalemia (low potassium levels), not hyperkalemia (high potassium levels). The other features of Conn's syndrome include alkalosis (metabolic), muscle cramps, and severe systemic hypertension.
Which of the following statements best describes Hashimoto's thyroiditis?
- A. Inflammation of the thyroid gland as the result of a virus. The disease is often preceded by an upper respiratory tract infection.
- B. A destructive autoimmune disease caused by auto-reactive antibodies against thyroglobulin.
- C. Iodine deficiency
- D. thyroid gland
Correct Answer: B
Rationale: Hashimoto's thyroiditis is an autoimmune disease where the immune system mistakenly attacks the thyroid gland. The antibodies produced by the immune system target the thyroglobulin in the thyroid gland, leading to its destruction over time. This results in decreased thyroid hormone production, leading to hypothyroidism. Therefore, choice B, "A destructive autoimmune disease caused by auto-reactive antibodies against thyroglobulin," best describes Hashimoto's thyroiditis.