ATI RN
Endocrinology Practice Questions Questions
Question 1 of 5
Klinefelter's syndrome is characterized by:
Correct Answer: A
Rationale: The correct answer is A because Klinefelter's syndrome is characterized by small, soft testes due to the presence of an extra X chromosome (47, XXY). This leads to hypogonadism and inadequate testosterone production, resulting in underdeveloped testes.
Choice B (46, XO) is incorrect as it refers to Turner syndrome.
Choice C (upper segment> lower segment) is unrelated to Klinefelter's syndrome.
Choice D (Gynaecomastia) is a symptom of Klinefelter's syndrome but not the defining characteristic.
Question 2 of 5
In injury to adrenal cortex, secretion of which is least affected?
Correct Answer: A
Rationale: The correct answer is A: Adrenaline. In injury to the adrenal cortex, adrenaline is least affected because it is primarily synthesized and secreted by the adrenal medulla, not the adrenal cortex. Cortisol, aldosterone, and androstenedione are hormones produced by the adrenal cortex. In adrenal cortex injury, the secretion of cortisol, aldosterone, and androstenedione would be significantly affected due to the damage to the adrenal cortex, leading to hormonal imbalance and related symptoms.
Therefore, option A is the correct answer as it is not primarily secreted by the adrenal cortex and would be least affected in this scenario.
Question 3 of 5
Excess prolactin gives rise to:
Correct Answer: B
Rationale: Excess prolactin causes gynaecomastia due to its stimulatory effect on breast tissue growth in males. Prolactin inhibits the release of testosterone, leading to an imbalance in sex hormones and breast tissue development. Acromegaly is caused by excess growth hormone, not prolactin. Early menopause is unrelated to prolactin levels. Anaemia is typically not associated with prolactin excess. Thus, gynaecomastia is the most appropriate outcome of excess prolactin.
Question 4 of 5
Oxytocin:
Correct Answer: A
Rationale:
Step-by-step rationale for why answer A is correct:
1. Oxytocin is synthesized in the hypothalamus and released into the bloodstream.
2. In the plasma, oxytocin binds to neurophysin, a carrier protein.
3. This binding helps stabilize oxytocin and regulate its release and distribution.
4.
Therefore, choice A is correct as oxytocin is bound to neurophysin in plasma.
Summary:
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Choice B is incorrect as oxytocin stimulates milk ejection, not inhibits milk production.
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Choice C is incorrect as oxytocin promotes myometrial contraction during labor.
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Choice D is incorrect as oxytocin can enhance sperm motility, not inhibit it.
Question 5 of 5
Which of the following is the most important mechanism of action of propylthiouracil in the treatment of Graves' disease?
Correct Answer: B
Rationale: The correct answer is B: Inhibition of the function of thyroid peroxidase. Propylthiouracil inhibits thyroid peroxidase, an enzyme essential for thyroid hormone synthesis. By blocking this enzyme, propylthiouracil reduces the production of thyroid hormones, helping to manage hyperthyroidism in Graves' disease.
Explanation:
1. Propylthiouracil directly inhibits thyroid peroxidase, unlike other antithyroid medications that target different mechanisms.
2. Inhibition of thyroid peroxidase leads to decreased synthesis of thyroid hormones, effectively controlling hyperthyroidism.
3. Other choices are incorrect because propylthiouracil does not primarily affect the production of thyroid-stimulating immunoglobulins (choice
A), peripheral conversion of T4 to T3 (choice
C), or iodine organification (choice
D) in the treatment of Graves' disease.
In summary, the inhibition of thyroid peroxidase by