Nokea
Which of the following sympathomimetics is not a catecholamine:
- A. Adrenaline
- B. Noradrenaline
- C. Amphetamine
- D. Isoprenaline
Correct Answer: C
Rationale: The correct answer is C: Amphetamine. Amphetamine is not a catecholamine because it is a synthetic drug, not naturally produced by the body like adrenaline (A), noradrenaline (B), and isoprenaline (D). Catecholamines are a class of neurotransmitters that include dopamine, adrenaline, and noradrenaline, all of which have a catechol group in their chemical structure. Amphetamine, on the other hand, is a substituted phenethylamine with no catechol group. This distinction makes amphetamine the only non-catecholamine among the given options.
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All but one of the following compounds releases large amounts of energy on breakdown:
- A. cAMP
- B. ATP
- C. creatine phosphate
- D. ADP
Correct Answer: A
Rationale: The correct answer is A: cAMP. cAMP, or cyclic adenosine monophosphate, does not release large amounts of energy on breakdown compared to the other choices. Here's the rationale:
1. ATP (Choice B) is known as the energy currency of the cell and releases a significant amount of energy when broken down.
2. Creatine phosphate (Choice C) is a high-energy compound that can rapidly donate its phosphate group to regenerate ATP.
3. ADP (Choice D) releases energy when converted to ATP through phosphorylation.
4. cAMP (Choice A) is a secondary messenger involved in signal transduction and does not store or release energy like ATP or creatine phosphate.
Which hormone is responsible for milk production in the mammary glands?
- A. somatotropin
- B. prolactin
- C. luteinizing hormone
- D. follicle-stimulating hormone
Correct Answer: B
Rationale: Prolactin is the correct answer because it is the hormone responsible for milk production in the mammary glands. It is secreted by the pituitary gland in response to the suckling stimulus from the baby. Prolactin stimulates the alveoli in the mammary glands to produce milk. Somatotropin (A), luteinizing hormone (C), and follicle-stimulating hormone (D) do not play a direct role in milk production. Somatotropin is involved in growth, luteinizing hormone is involved in ovulation, and follicle-stimulating hormone is involved in the development of ovarian follicles.
Parasympathomimetic drugs are drugs that:
- A. Inhibit muscarinic receptors
- B. Inhibit release of acetylcholine
- C. Inhibit adrenergic receptors
- D. Stimulate muscarinic receptors
Correct Answer: D
Rationale: The correct answer is D: Stimulate muscarinic receptors. Parasympathomimetic drugs mimic the actions of the parasympathetic nervous system, which primarily uses acetylcholine on muscarinic receptors to produce its effects. By stimulating muscarinic receptors, these drugs enhance parasympathetic activity.
A, B, and C are incorrect:
A: Inhibiting muscarinic receptors would have the opposite effect of parasympathomimetic drugs.
B: Inhibiting the release of acetylcholine would also reduce parasympathetic activity.
C: Inhibiting adrenergic receptors pertains to the sympathetic nervous system, not the parasympathetic system targeted by parasympathomimetic drugs.
Propranolol can produce the following EXCEPT:
- A. Stimulation of beta adrenergic receptors
- B. Blockade of beta adrenergic receptors
- C. Depression of cardiac contractility
- D. Decreased blood pressure
Correct Answer: A
Rationale: The correct answer is A: Stimulation of beta adrenergic receptors. Propranolol is a beta-blocker that works by blocking beta adrenergic receptors, not stimulating them. Blocking these receptors leads to decreased heart rate, reduced cardiac contractility, and lowered blood pressure. Choices B, C, and D are incorrect because propranolol actually blocks beta adrenergic receptors, depresses cardiac contractility, and decreases blood pressure, respectively.
As plasma levels of calcium decrease:
- A. insulin is secreted.
- B. the parathyroid glands secrete an osteoclastic hormone.
- C. the kidneys excrete calcium and phosphorus.
- D. calcitonin is secreted.
Correct Answer: B
Rationale: The correct answer is B because as plasma levels of calcium decrease, the parathyroid glands secrete an osteoclastic hormone called parathyroid hormone (PTH). PTH acts to increase calcium levels by stimulating the release of calcium from bones via osteoclasts. Insulin secretion (choice A) is not directly related to calcium levels. The kidneys excreting calcium and phosphorus (choice C) would further decrease calcium levels. Calcitonin (choice D) actually decreases blood calcium levels by inhibiting bone breakdown, so it is not secreted when calcium levels decrease.