Nokea
Mineralcorticoids
- A. are produced in the adrenal cortex.
- B. are steroid hormones.
- C. help regulate the homeostasis of sodium and potassium.
- D. All of the above.
Correct Answer: D
Rationale: 1. Mineralocorticoids are hormones produced in the adrenal cortex (A).
2. They are steroid hormones (B) that specifically regulate sodium and potassium homeostasis (C).
3. Therefore, the correct answer is D, as mineralocorticoids encompass all these characteristics. Other choices are incorrect as they do not fully encompass the functions and characteristics of mineralocorticoids.
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A 43-year-old woman with diagnosed myasthenia gravis presents with profound skeletal muscle weakness. We are unsure whether she is experiencing a cholinergic crisis or a myasthenic crisis, so we administer a usually appropriate dose of parenteral edrophonium. Assume the patient was actually experiencing a cholinergic crisis. Which of the following is the most likely response to the drug?
- A. Hypertensive crisis from peripheral vascular constriction
- B. Myocardial ischemia, and angina, from drug-induced tachycardia and coronary vasoconstriction
- C. Premature ventricular contractions from increased ventricular automaticity
- D. Ventilatory distress or failure
Correct Answer: D
Rationale: The correct answer is D: Ventilatory distress or failure. Edrophonium is a short-acting acetylcholinesterase inhibitor used to differentiate between myasthenic and cholinergic crises. In a cholinergic crisis, which is an excess of acetylcholine, administering edrophonium can worsen symptoms due to further acetylcholine accumulation. This can lead to excessive stimulation of the respiratory muscles, resulting in ventilatory distress or failure.
Choice A is incorrect because cholinergic crisis typically causes hypotension, not hypertension. Choice B is incorrect because edrophonium-induced tachycardia can worsen myocardial ischemia, not angina. Choice C is incorrect because increased ventricular automaticity would not be a common response to edrophonium in a cholinergic crisis.
Which of the following hormones are responsible for the 'fight-or-flight' response?
- A. Epinephrine and norepinephrine.
- B. Insulin and glucagon.
- C. Esrtogen and progesterone.
- D. Thyroxin and melatonin.
Correct Answer: A
Rationale: The correct answer is A: Epinephrine and norepinephrine. These hormones are released by the adrenal glands during stressful situations to trigger the 'fight-or-flight' response. They increase heart rate, blood pressure, and energy production to prepare the body for action. Insulin and glucagon (B) regulate blood sugar levels. Estrogen and progesterone (C) are female sex hormones. Thyroxin and melatonin (D) are involved in metabolism and sleep regulation, respectively. Therefore, only A directly relates to the physiological response of 'fight-or-flight'.
Which is not Na+ dependent for absorption?
- A. thiamin
- B. riboflavin
- C. niacin
- D. folate
Correct Answer: D
Rationale: The correct answer is D. Folate absorption is not Na+ dependent because it is absorbed in the small intestine through a carrier-mediated process independent of sodium. Thiamin, riboflavin, and niacin require sodium-dependent transport mechanisms for absorption in the small intestine. Thiamin is absorbed through thiamin transporters that are Na+ dependent. Riboflavin is absorbed by sodium-dependent multivitamin transporters. Niacin absorption also involves sodium-dependent transporters. Therefore, folate is the only option that is not Na+ dependent for absorption.
If farmers exposed to 'insecticides' ('irreversible' cholinesterase inhibitors) are given medical kits that contain atropine. Which one of the following effects of the cholinesterase inhibitor will NOT be blocked by the atropine?
- A. Bronchoconstriction / bronchospasm
- B. Increased bladder/urinary tract activity
- C. Increased bowel motility (i.e., diarrhea)
- D. Skeletal muscle overstimulation, eventually leading to skeletal muscle paralysis
Correct Answer: D
Rationale: The correct answer is D. Atropine blocks the effects of cholinesterase inhibitors on muscarinic receptors but not on nicotinic receptors, which are responsible for skeletal muscle overstimulation. Atropine can block bronchoconstriction, increased bladder activity, and increased bowel motility as they are mediated by muscarinic receptors. Therefore, the effects on skeletal muscle overstimulation, leading to paralysis, will not be blocked by atropine.
Which of the following elements is required for the synthesis of thyroid hormone?
- A. copper
- B. iodine
- C. sulfur
- D. zinc
Correct Answer: B
Rationale: The correct answer is B: iodine. Iodine is an essential element required for the synthesis of thyroid hormone. Thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) contain iodine atoms. Without sufficient iodine, the thyroid gland cannot produce these hormones, leading to thyroid disorders like hypothyroidism or goiter. Copper (A), sulfur (C), and zinc (D) are not directly involved in the synthesis of thyroid hormone. Copper is important for enzyme function, sulfur is present in amino acids, and zinc is involved in various cellular processes but not specifically in thyroid hormone synthesis.