Nokea
Which of the following is the most reliable thyroid function test to diagnose hyperthyroidism in an older adult?
- A. Serum T3 level
- B. Glucose tolerance test
- C. Cosyntropin
- D. Iodine tolerance test
Correct Answer: A
Rationale: Serum T3 levels are the most reliable test to diagnose hyperthyroidism in older adults, as thyroid hormone levels are often altered in this population.
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Which of the following is a direct-acting parasympathomimetic that readily passes the blood-brain barrier and is commonly used in the treatment of glaucoma:
- A. Pilocarpine
- B. Carbachol
- C. Methacholine
- D. Bethanechol
Correct Answer: A
Rationale: The correct answer is A: Pilocarpine. Pilocarpine is a direct-acting parasympathomimetic that readily passes the blood-brain barrier due to its small molecular size. It is commonly used in the treatment of glaucoma by constricting the pupil and increasing the outflow of aqueous humor. Carbachol and Bethanechol are also parasympathomimetics, but they do not readily cross the blood-brain barrier. Methacholine is a muscarinic receptor agonist, not commonly used in the treatment of glaucoma. Therefore, the most suitable choice that meets the criteria provided in the question is pilocarpine.
Regarding the islets of Langerhans:
- A. D cells secrete pancreatic polypeptide
- B. A cells are the most common
- C. they are most plentiful in the body of the pancreas
- D. blood from the islets drain into the hepatic portal vein
Correct Answer: D
Rationale: The correct answer is D because blood from the islets of Langerhans drains into the hepatic portal vein. This is important for the regulation of blood glucose levels by allowing insulin and glucagon produced by the islets to reach the liver directly. Choice A is incorrect because D cells secrete somatostatin, not pancreatic polypeptide. Choice B is incorrect as beta cells, not A cells, are the most common in the islets. Choice C is incorrect as the islets are most plentiful in the tail of the pancreas.
Which is NOT an action of CCK?
- A. gallbladder contraction
- B. increased gastric motility and emptying
- C. glucagon secretion
- D. secretion of pancreatic juice
Correct Answer: B
Rationale: The correct answer is B: increased gastric motility and emptying. Cholecystokinin (CCK) is a hormone that primarily functions to stimulate gallbladder contraction (A), secretion of pancreatic juice (D), and inhibit gastric motility and emptying. Choice C, glucagon secretion, is not directly related to the actions of CCK. The incorrect choices (A, C, D) are all actions associated with CCK, while choice B goes against the typical action of CCK on gastric motility.
An excess of thyroid hormones produces hyperthyroidism, a speeded-up metabolic state that is known as:
- A. Cushing syndrome.
- B. Graves’ disease.
- C. Addison’s disease.
- D. ADH hypersecretion.
Correct Answer: B
Rationale: The correct answer is B: Graves' disease. Graves' disease is an autoimmune disorder that leads to overproduction of thyroid hormones, causing hyperthyroidism. This is characterized by symptoms such as weight loss, increased heart rate, and anxiety. Cushing syndrome (A) is caused by excess cortisol, not thyroid hormones. Addison's disease (C) is a condition where the adrenal glands do not produce enough hormones. ADH hypersecretion (D) refers to excessive production of antidiuretic hormone, not thyroid hormones. Therefore, the correct answer is Graves' disease due to its direct association with hyperthyroidism.
Iodination of thyroid hormones is mediated by __________.
- A. lysosomes in the cell
- B. the Golgi apparatus
- C. colloid endocytosis
- D. peroxidase enzymes
Correct Answer: D
Rationale: The correct answer is D: peroxidase enzymes. Peroxidase enzymes are responsible for catalyzing the iodination process of thyroid hormones in the thyroid gland. They facilitate the incorporation of iodine atoms into tyrosine residues within thyroglobulin to form thyroid hormones T3 and T4. Lysosomes (choice A) are involved in cellular waste disposal, not iodination. The Golgi apparatus (choice B) is responsible for processing and packaging proteins, not iodination. Colloid endocytosis (choice C) is the process of internalizing colloid-containing vesicles in thyroid follicular cells, but it is not directly involved in iodination.