Nokea
A girl presents with delayed puberty, absent secondary sexual characteristics, and primary amenorrhea. She also appears to be hypertensive and hypokalemia. Which of the following enzymes is increased if there is virilization of a person?
- A. 11b-Hydroxylase
- B. 17a-Hydroxylase
- C. 21b-Hydroxylase
- D. Pyruvate Kinase
Correct Answer: A
Rationale: The correct answer is A: 11b-Hydroxylase. In cases of virilization, increased androgen production occurs. 11b-Hydroxylase is involved in the synthesis of cortisol and aldosterone. When there is a deficiency in this enzyme, excess androgens are diverted towards the production of testosterone, leading to virilization. In contrast, choices B (17a-Hydroxylase) and C (21b-Hydroxylase) deficiencies result in decreased androgen production. Choice D, Pyruvate Kinase, is not related to steroid hormone synthesis. Therefore, the correct enzyme in this scenario is 11b-Hydroxylase.
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Ritodrine is a drug indicated for suppressing uterine contractions in premature labor. The drug also causes bronchodilation. It has no vasoconstrictor effects, nor any effects on the size of the pupil of the eye. Which of the following is the most likely classification of this drug?
- A. α-adrenergic agonist
- B. Antimuscarinic drug
- C. β-adrenergic agonist
- D. β-adrenergic blocker
Correct Answer: C
Rationale: The correct answer is C: β-adrenergic agonist. Ritodrine is indicated for suppressing uterine contractions, which is a typical effect of β-adrenergic agonists. Bronchodilation is also a known effect of β-adrenergic agonists. Since the drug has no vasoconstrictor effects and does not affect the size of the pupil of the eye, it is unlikely to be an α-adrenergic agonist or an antimuscarinic drug. Additionally, the fact that ritodrine causes bronchodilation further supports its classification as a β-adrenergic agonist.
The posterior pituitary stores and releases:
- A. Growth hormone and prolactin.
- B. Prolactin and oxytocin.
- C. Oxytocin and antidiuretic hormone (ADH).
- D. ADH and growth hormone.
Correct Answer: C
Rationale: The correct answer is C: Oxytocin and antidiuretic hormone (ADH). The posterior pituitary stores and releases oxytocin and ADH, also known as vasopressin. Oxytocin is involved in uterine contractions and milk ejection, while ADH regulates water reabsorption in the kidneys. Choices A, B, and D are incorrect because the posterior pituitary does not store or release growth hormone or prolactin.
Oxytocin:
- A. is a neurohypophyseal hormone that stimulates the uterine muscle to contract, thereby assisting in labor.
- B. is a gonadotropin.
- C. stimulates the kidney to reabsorb Na+ and water, thereby expanding blood volume.
- D. is a mineralocorticoid.
Correct Answer: A
Rationale: Rationale:
1. Oxytocin is a neurohypophyseal hormone secreted by the posterior pituitary gland.
2. It plays a key role in stimulating uterine contractions during labor and childbirth.
3. This action helps in the progression of labor by promoting the expulsion of the fetus.
4. Oxytocin also stimulates milk ejection during breastfeeding.
5. Choice A is correct as it accurately describes the role of oxytocin in uterine muscle contraction.
Summary:
B: Oxytocin is not a gonadotropin; it does not directly affect gonadal function.
C: Oxytocin does not stimulate the kidney to reabsorb Na+ and water; that is the role of other hormones like aldosterone.
D: Oxytocin is not a mineralocorticoid; it does not regulate electrolyte balance like mineralocorticoids do.
The transcription of new messenger RNA is a function of __________.
- A. pancreatic hormones
- B. steroid hormones
- C. catecholamines
- D. pituitary gland hormones
Correct Answer: B
Rationale: The correct answer is B: steroid hormones. Steroid hormones are known to regulate gene expression by binding to specific receptors and influencing transcription processes. They can directly affect the transcription of new messenger RNA in the cell. Pancreatic hormones (A), catecholamines (C), and pituitary gland hormones (D) are not directly involved in the transcription of new messenger RNA. Pancreatic hormones primarily regulate blood sugar levels, catecholamines are involved in the fight-or-flight response, and pituitary gland hormones regulate various functions such as growth, reproduction, and metabolism.
Which drug is most likely to cause muscle tremor:
- A. Ipratropium
- B. Terbutaline
- C. Atenolol
- D. Nicotinic acid
Correct Answer: B
Rationale: The correct answer is B: Terbutaline. Terbutaline is a beta-2 adrenergic agonist used as a bronchodilator. It can stimulate beta-2 receptors in skeletal muscle, leading to muscle tremors as a common side effect. Ipratropium (A) is an anticholinergic bronchodilator and typically does not cause muscle tremors. Atenolol (C) is a beta-blocker and is not associated with muscle tremors. Nicotinic acid (D) is used to treat dyslipidemia and does not commonly cause muscle tremors. Therefore, Terbutaline is the most likely drug to cause muscle tremor among the options provided.