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In hyperthyroidism, which of the following lab findings would you expect?
- A. Increased TSH, decreased T3, T4
- B. Decreased TSH, increased T3, T4
- C. Increased TSH, increased T3, T4
- D. Decreased TSH, decreased T3, T4
Correct Answer: B
Rationale: The correct answer is B. In hyperthyroidism, the thyroid gland produces an excess of thyroid hormones T3 and T4, leading to negative feedback on the pituitary gland, resulting in decreased TSH levels. Therefore, you would expect decreased TSH and increased T3, T4 levels. A is incorrect because TSH would be decreased, not increased. C is incorrect because TSH would be decreased in hyperthyroidism. D is incorrect because T3 and T4 would be increased in hyperthyroidism.
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Which of the following posterior pituitary hormones causes the kidney to decrease its excretion of urine?
- A. ADH
- B. ACTH
- C. Aldosterone
- D. Oxytocin
Correct Answer: A
Rationale: Correct answer: A (ADH)
Rationale:
1. ADH (Antidiuretic hormone) acts on the kidneys to increase water reabsorption, leading to decreased urine output.
2. ACTH (Adrenocorticotropic hormone) stimulates the adrenal glands, not the kidneys.
3. Aldosterone acts on the kidneys to regulate electrolyte balance, not directly affecting urine volume.
4. Oxytocin primarily functions in uterine contractions and milk ejection, not in kidney function.
Isoprenaline produces the following actions EXCEPT:
- A. Direct stimulation of beta adrenoceptors
- B. Relaxation of bronchial smooth muscles
- C. Decreased blood pressure
- D. Increased intestinal motility
Correct Answer: D
Rationale: Step-by-step rationale:
1. Isoprenaline is a beta-adrenergic agonist.
2. It directly stimulates beta adrenoceptors, leading to effects like increased heart rate.
3. Isoprenaline causes bronchodilation by relaxing bronchial smooth muscles.
4. It also causes vasodilation, leading to decreased blood pressure.
5. Isoprenaline does not have a direct effect on intestinal motility, making option D incorrect.
Summary:
Option D is incorrect as isoprenaline does not increase intestinal motility. Options A, B, and C are correct as isoprenaline directly stimulates beta adrenoceptors, relaxes bronchial smooth muscles, and decreases blood pressure, respectively.
Which mechanism is primarily responsible for maintaining hormone levels within a narrow range?
- A. negative feedback mechanisms
- B. positive feedback mechanisms
- C. hormone-receptor complexes
- D. hormone-gene complexes
Correct Answer: A
Rationale: The correct answer is A: negative feedback mechanisms. Negative feedback mechanisms help maintain hormone levels within a narrow range by inhibiting further hormone production once a certain level is reached. When hormone levels rise, negative feedback signals the body to decrease hormone production, preventing excessive levels. Positive feedback mechanisms, on the other hand, amplify hormone production. Hormone-receptor complexes and hormone-gene complexes are not directly responsible for maintaining hormone levels within a narrow range but rather play roles in hormone signaling and gene expression, respectively.
The hypothalamic-hypophyseal tract ________.
- A. connects the hypophysis to the pituitary gland
- B. is partly contained within the infundibulum
- C. conducts aldosterone to the hypophysis
- D. is the site of prolactin synthesis
Correct Answer: B
Rationale: The correct answer is B because the hypothalamic-hypophyseal tract is indeed partly contained within the infundibulum, which is a stalk-like structure connecting the hypothalamus to the pituitary gland. This pathway is crucial for the release of hormones from the hypothalamus to the pituitary gland. Choice A is incorrect as the hypophysis and pituitary gland are the same structure. Choice C is incorrect as aldosterone is a hormone produced by the adrenal glands, not related to the hypothalamic-pituitary axis. Choice D is incorrect because prolactin synthesis occurs in the lactotroph cells of the anterior pituitary, not in the hypothalamic-hypophyseal tract.
A 10-year-old boy is diagnosed with Attention Deficit/Attention Deficit-Hyperactivity disorder (ADD/ADHD). Which of the following drugs is most likely to prove effective for relieving the boy’s main symptoms?
- A. Dobutamine
- B. Amphetamine
- C. Pancuronium
- D. Prazosin
Correct Answer: B
Rationale: The correct answer is B: Amphetamine. Amphetamine is a stimulant commonly used to treat symptoms of ADHD as it helps improve focus, impulse control, and hyperactivity. It works by increasing the levels of certain neurotransmitters in the brain. Dobutamine (A) is a different type of stimulant used for heart conditions. Pancuronium (C) is a muscle relaxant used during surgery, and Prazosin (D) is an alpha-blocker used for high blood pressure and PTSD nightmares. Therefore, Amphetamine is the most likely drug to be effective for relieving the boy's main symptoms of ADHD.