Exam Questions on Endocrine System

Exam Questions on Endocrine System Related

Review Exam Questions on Endocrine System related questions and content

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

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Androgens are produced by the _______.

  • A. ovaries.
  • B. testes.
  • C. hypothalamus.
  • D. islets of Langerhans.
Correct Answer: B

Rationale: The correct answer is B: testes. Androgens, such as testosterone, are male sex hormones primarily produced by the testes. The testes contain specialized cells called Leydig cells that secrete androgens. Ovaries (A) produce female sex hormones like estrogen and progesterone. The hypothalamus (C) regulates hormone production through the pituitary gland but does not directly produce androgens. Islets of Langerhans (D) are clusters of cells in the pancreas responsible for producing insulin and glucagon, not androgens.

Which of the following symptoms of diabetes mellitus is correctly matched to its description?

  • A. polyuria - excessive thirst
  • B. polyphagia - excessive ketones in the blood
  • C. polydipsia - excessive urine
  • D. glycosuria - excessive sugar in the urine
Correct Answer: D

Rationale: The correct answer is D, glycosuria - excessive sugar in the urine. In diabetes mellitus, high blood sugar levels lead to glucose spilling into the urine, causing glycosuria. Polyuria (excessive urine) is due to the kidneys trying to eliminate the excess glucose. Polyphagia (excessive hunger) results from cells not receiving enough glucose for energy. Polydipsia (excessive thirst) occurs as a result of dehydration from polyuria. Choice D is correct as it directly relates to the presence of sugar in the urine, a hallmark symptom of diabetes mellitus.

Which gland secretes TSH, ACTH, and growth hormone?

  • A. Neurohypophysis
  • B. Pancreas
  • C. Adrenal medulla
  • D. Anterior pituitary gland
Correct Answer: D

Rationale: The correct answer is D, the anterior pituitary gland, because it secretes TSH, ACTH, and growth hormone. The anterior pituitary gland is also known as the adenohypophysis, and it plays a key role in regulating various bodily functions through the release of different hormones. The other choices are incorrect because the neurohypophysis (choice A) secretes hormones like oxytocin and vasopressin, the pancreas (choice B) secretes insulin and glucagon, and the adrenal medulla (choice C) secretes adrenaline and noradrenaline.

The binding of a steroid hormone to its receptor would lead to the __________.

  • A. transcription of the DNA for the gene that is 'turned on' by this event
  • B. direct activation of second-messenger agents in the cell
  • C. direct activation of enzymes in the cell
  • D. formation of cAMP
Correct Answer: A

Rationale: The correct answer is A because the binding of a steroid hormone to its receptor triggers a series of events that ultimately lead to the transcription of DNA for the gene that is 'turned on'. This process involves the hormone-receptor complex entering the nucleus, binding to specific DNA sequences, recruiting transcription factors, and initiating gene expression.

Choice B is incorrect because steroid hormones do not typically use second messengers for signaling. Choice C is incorrect because while some hormones can activate enzymes indirectly, steroid hormones primarily act through gene transcription. Choice D is incorrect because cAMP is typically associated with signaling pathways involving non-steroid hormones like adrenaline.

Adam has just been diagnosed with diabetes insipidus. The most common presenting sign is:

  • A. Body wasting.
  • B. Hyperglycemia.
  • C. Hypoglycemia.
  • D. Increase in urination.
Correct Answer: D

Rationale: The hallmark symptom of diabetes insipidus is polyuria (excessive urination), which occurs due to the kidney's inability to concentrate urine.

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