Nokea
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.
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Cretinism, myxedema, and Graves’ disease are all:
- A. thyroid hormone deficiency diseases.
- B. thyroid hormone disorders caused by oversecretion of thyroxine.
- C. calcium imbalances due primarily to the lack of calcitonin.
- D. disorders of thyroid gland function.
Correct Answer: D
Rationale: Step 1: Cretinism, myxedema, and Graves' disease are all related to thyroid gland function.
Step 2: Cretinism is a congenital hypothyroidism, myxedema is adult hypothyroidism, and Graves' disease is hyperthyroidism.
Step 3: Thus, they are all disorders of thyroid gland function.
Summary:
- Choice A is incorrect because they are not all thyroid hormone deficiency diseases.
- Choice B is incorrect because they are not all caused by oversecretion of thyroxine.
- Choice C is incorrect because they are not primarily related to calcium imbalances due to lack of calcitonin.
The term catecholamine best describes drugs that are:
- A. Adrenergic receptor blockers
- B. Atropine-like in terms of their mechanisms and sites of action
- C. Classified like neostigmine and physostigmine
- D. Similar to adrenaline and noradrenaline in terms of structure and major pharmacologic properties
Correct Answer: D
Rationale: The correct answer is D because catecholamines are structurally similar to adrenaline and noradrenaline, sharing a catechol nucleus and amine group. This similarity allows them to exert similar pharmacologic effects such as increasing heart rate and blood pressure. Adrenergic receptor blockers (A) inhibit the action of catecholamines, atropine-like drugs (B) block muscarinic receptors, and neostigmine and physostigmine (C) are cholinesterase inhibitors, not catecholamines.
Your patient is diagnosed with myasthenia gravis, and she is given a prescription for pyridostigmine. Which of the following best summarizes the drug’s mechanism of action?
- A. Blocks muscarinic receptors, so that acetylcholine preferentially stimulates skeletal muscle
- B. Inhibits reuptake of acetylcholine by motor nerves
- C. Inhibits skeletal muscle activation at rest so that the muscles are less susceptible to fatigue during exercise
- D. Inhibits breakdown of acetylcholine, thereby improving activation of skeletal muscle by acetylcholine
Correct Answer: D
Rationale: The correct answer is D: "Inhibits breakdown of acetylcholine, thereby improving activation of skeletal muscle by acetylcholine."
Rationale:
1. Pyridostigmine is an acetylcholinesterase inhibitor, which means it blocks the breakdown of acetylcholine.
2. In myasthenia gravis, there is a decrease in acetylcholine receptor sites, leading to muscle weakness.
3. By inhibiting the breakdown of acetylcholine, pyridostigmine increases the availability of acetylcholine at the neuromuscular junction, improving muscle activation.
4. This mechanism helps alleviate muscle weakness in myasthenia gravis patients.
Summary:
A: Incorrect. Pyridostigmine does not block muscarinic receptors or change the preference of acetylcholine stimulation.
B: Incorrect. Pyridostigmine does not inhibit reuptake of acetylcholine; it acts by inhibiting its breakdown
A 38-year-old man with galactorrhea is treated with bromocriptine, which eliminates the galactorrhea. The basis for the therapeutic action of bromocriptine is that it
- A. antagonizes the action of prolactin on the breast
- B. enhances the action of prolactin on the breast
- C. inhibits prolactin release from the anterior pituitary
- D. inhibits prolactin release from the hypothalamus
Correct Answer: C
Rationale: Step-by-step rationale:
1. Bromocriptine is a dopamine agonist.
2. Dopamine inhibits prolactin release from the anterior pituitary.
3. Galactorrhea is often caused by excess prolactin.
4. By inhibiting prolactin release, bromocriptine reduces prolactin levels and eliminates galactorrhea.
Summary:
A: Incorrect - Bromocriptine does not antagonize prolactin action.
B: Incorrect - Bromocriptine does not enhance prolactin action.
D: Incorrect - Prolactin is not released from the hypothalamus.
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.