Nokea
Which tracheal rings are generally related to isthmus?
- A. 1st and 2nd
- B. 1st, 2nd and 3rd
- C. 2nd and 3rd
- D. 2nd, 3rd and 4th
Correct Answer: C
Rationale: Rationale:
The isthmus of the thyroid gland is located between the 2nd and 3rd tracheal rings. These rings provide support to the trachea and help maintain its shape. Therefore, the correct answer is C.
Summary of other choices:
A: 1st and 2nd - Incorrect, as the isthmus is not related to the 1st tracheal ring.
B: 1st, 2nd and 3rd - Incorrect, as the isthmus is only between the 2nd and 3rd tracheal rings.
D: 2nd, 3rd and 4th - Incorrect, as the isthmus does not extend to the 4th tracheal ring.
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Regarding iron:
- A. it is more readily absorbed in the ferric form
- B. men lose about 0.6mg/d
- C. average daily iron intake is 40mg
- D. ascorbic acid reduces iron absorption
Correct Answer: B
Rationale: The correct answer is B because men lose about 0.6mg of iron per day through various physiological processes like shedding skin cells and hair. This loss must be replenished through dietary intake to maintain iron balance. Choice A is incorrect as iron is more readily absorbed in the ferrous form. Choice C is incorrect as the average daily iron intake is around 18mg. Choice D is incorrect ascorbic acid enhances iron absorption rather than reducing it.
You are a resident in a hospital in a very poor part of the world. Their drug selection is limited. A patient presents with acute cardiac failure, for which your preferred drug is dobutamine, given intravenously. However, there is none available. Which of the following other drugs, or combination of drugs, would be a suitable alternative?
- A. Dopamine (at a very high dose)
- B. Ephedrine
- C. Ephedrine plus propranolol
- D. Norepinephrine plus phentolamine
Correct Answer: D
Rationale: The correct answer is D: Norepinephrine plus phentolamine. Norepinephrine is a potent vasopressor that can increase blood pressure and cardiac output in acute cardiac failure. Phentolamine is an alpha-blocker that can help counteract the vasoconstrictive effects of norepinephrine.
Rationale:
1. Norepinephrine: Increases blood pressure and cardiac output, improving perfusion to vital organs in acute cardiac failure.
2. Phentolamine: Counteracts the vasoconstrictive effects of norepinephrine, preventing excessive vasoconstriction.
Summary:
A: Dopamine at a very high dose may not be as effective as norepinephrine in acute cardiac failure.
B: Ephedrine is a less potent vasopressor compared to norepinephrine.
C: Ephedrine plus propranolol combination may lead to conflicting effects on blood pressure and heart rate
Which two elements react together to form an ionic compound?
- A. R and T
- B. T and X
- C. X and Z
- D. Z and R
Correct Answer: C
Rationale: The correct answer is C, X and Z. Ionic compounds are formed when a metal (X) reacts with a nonmetal (Z) by transferring electrons to achieve a stable octet configuration. Metal atoms tend to lose electrons to form positively charged cations, while nonmetal atoms tend to gain electrons to form negatively charged anions. In this case, X (metal) and Z (nonmetal) will react to form an ionic compound through electron transfer. Choices A, B, and D are incorrect because they do not involve a metal-nonmetal combination, which is essential for the formation of an ionic compound.
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
Steroid hormones:
- A. require a second messenger.
- B. are secreted by the adrenal cortex.
- C. are secreted by the posterior pituitary.
- D. are secreted by the pancreas.
Correct Answer: B
Rationale: The correct answer is B: Steroid hormones are secreted by the adrenal cortex. The adrenal cortex is responsible for producing steroid hormones such as cortisol, aldosterone, and sex hormones. This is supported by the understanding of endocrine gland functions. Choices A, C, and D are incorrect because steroid hormones do not require a second messenger, are not secreted by the posterior pituitary, and are not secreted by the pancreas. Understanding the specific glands and their hormone production is crucial in selecting the correct answer.