Nokea
Which of the following statements about anticholinesterase drugs is WRONG:
- A. They can be divided into reversible and irreversible types
- B. They include neostigmine and physostigmine
- C. They can produce miosis and lacrimation
- D. They are useful bronchodilators
Correct Answer: D
Rationale: The correct answer is D because anticholinesterase drugs are not bronchodilators; they actually increase cholinergic activity by inhibiting the breakdown of acetylcholine. Reversible and irreversible types do exist (A), neostigmine and physostigmine are examples (B), and they can cause miosis and lacrimation due to increased cholinergic activity (C). Hence, D is the incorrect statement.
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We have a 48-year-old female patient with a history of myasthenia gravis. She has been treated with an oral acetylcholinesterase inhibitor for several years and has done well till now. She presents with muscle weakness and other signs and symptoms that could reflect either a cholinergic crisis (excess dosages of her maintenance drug) or a myasthenic crisis (insufficient treatment). We will use a rapidly acting parenteral acetylcholinesterase inhibitor (AChE) to help make the differential diagnosis. Which of the following drugs would be most appropriate for this use?
- A. Edrophonium
- B. Malathion
- C. Physostigmine
- D. Pralidoxime
Correct Answer: A
Rationale: The correct answer is A: Edrophonium. Edrophonium is a short-acting acetylcholinesterase inhibitor that can help differentiate between a cholinergic crisis and a myasthenic crisis. In this scenario, administering edrophonium will temporarily increase acetylcholine levels at the neuromuscular junction. If the patient's symptoms improve following edrophonium administration, it suggests a myasthenic crisis due to insufficient treatment. On the other hand, if the symptoms worsen, it indicates a cholinergic crisis due to excess dosages of the maintenance drug.
Choice B: Malathion is an organophosphate insecticide and is not used for diagnosing myasthenia gravis.
Choice C: Physostigmine is a longer-acting acetylcholinesterase inhibitor and is not appropriate for rapidly assessing the patient's condition in this scenario.
Choice D: Pralidoxime is used as an antidote for organophosphate
The body’s major metabolic hormone is released from the:
- A. Pituitary
- B. Thyroid
- C. Thymus
- D. Hypothalamus
Correct Answer: B
Rationale: The correct answer is B: Thyroid. The body's major metabolic hormone, thyroxine (T4) and triiodothyronine (T3), is released from the thyroid gland. The thyroid gland plays a crucial role in regulating metabolism. Pituitary (A) releases various hormones but not the major metabolic hormone. Thymus (C) is responsible for immune function, not metabolism. Hypothalamus (D) regulates the pituitary gland but does not directly release the major metabolic hormone.
Which of the following is least characteristic of the function of insulin?
- A. Increases glucose transport (into the cell).
- B. Suppresses gluconeogenesis.
- C. Lowers blood glucose.
- D. Increases the generation of ketone bodies.
Correct Answer: D
Rationale: The correct answer is D because insulin does not increase the generation of ketone bodies. Insulin actually inhibits ketogenesis by promoting glucose utilization and storage, preventing the breakdown of fats for energy. A, B, and C are all characteristics of insulin's function: A) Insulin increases glucose transport into the cell to lower blood glucose levels; B) It suppresses gluconeogenesis, the production of new glucose in the liver; C) Insulin lowers blood glucose levels by promoting the uptake and storage of glucose in cells.
Pralidoxime is a cholinesterase reactivator used in the treatment of toxicity by:
- A. Atropine
- B. Nicotine
- C. Organic phosphate
- D. Amphetamine
Correct Answer: C
Rationale: The correct answer is C: Organic phosphate. Pralidoxime is used to treat toxicity caused by organophosphates, which inhibit cholinesterase enzymes. Pralidoxime works by reactivating the inhibited cholinesterase enzymes, restoring their function. Atropine is used to counteract the effects of excessive acetylcholine in cholinergic toxicity, not organophosphate poisoning. Nicotine is a nicotinic receptor agonist and not treated with pralidoxime. Amphetamine is a central nervous system stimulant and does not involve cholinesterase inhibition. Therefore, the correct answer is C as pralidoxime is specifically used to treat toxicity caused by organophosphates.
Insulin:
- A. is secreted by the beta cells of the islets of Langerhans.
- B. is secreted by the liver.
- C. raises blood glucose levels.
- D. is released by the pancreas in response to low blood glucose levels.
Correct Answer: A
Rationale: Step-by-step rationale:
1. Insulin is a hormone that regulates blood glucose levels by promoting glucose uptake into cells.
2. Beta cells of the islets of Langerhans in the pancreas are responsible for secreting insulin.
3. Insulin lowers blood glucose levels by enhancing glucose uptake and storage.
4. Therefore, choice A is correct as it accurately identifies the source of insulin secretion.
Summary:
- Choice B is incorrect as the liver does not secrete insulin.
- Choice C is incorrect as insulin lowers blood glucose levels.
- Choice D is incorrect as insulin is released in response to high, not low, blood glucose levels.