Nokea
Calcitonin and parathyroid hormone:
- A. are both secreted by the parathyroid glands.
- B. increase plasma levels of calcium.
- C. decrease plasma levels of calcium.
- D. control plasma levels of calcium.
Correct Answer: D
Rationale: Correct Answer: D
Rationale: Calcitonin and parathyroid hormone regulate plasma calcium levels. Calcitonin decreases calcium levels by inhibiting bone breakdown, while parathyroid hormone increases calcium levels by stimulating bone breakdown and increasing calcium reabsorption. Therefore, both hormones work together to maintain calcium homeostasis. The correct answer, choice D, highlights that both hormones control plasma calcium levels.
Summary of Other Choices:
A: Incorrect. Calcitonin is secreted by the thyroid gland, not the parathyroid glands.
B: Incorrect. Calcitonin decreases plasma calcium levels, while parathyroid hormone increases plasma calcium levels.
C: Incorrect. Parathyroid hormone increases plasma calcium levels, whereas calcitonin decreases plasma calcium levels.
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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.
Which layer of cervical fascia forms the false capsule of thyroid gland?
- A. Carotid sheath
- B. Investing layer
- C. Pretracheal fascia
- D. Prevertebral fascia
Correct Answer: C
Rationale: The correct answer is C: Pretracheal fascia. This layer surrounds the thyroid gland, forming the false capsule. It separates the thyroid from the strap muscles anteriorly and the trachea and esophagus posteriorly. The Carotid sheath (A) encloses the common carotid artery, internal jugular vein, and vagus nerve. The Investing layer (B) covers the sternocleidomastoid and trapezius muscles. The Prevertebral fascia (D) surrounds the vertebral column and deep neck muscles, not directly related to the thyroid gland.
Priority Decision: A patient with diabetes calls the clinic because she is experiencing nausea and flu-like symptoms. Which advice from the nurse will be the best for this patient?
- A. Administer the usual insulin dosage.
- B. Hold fluid intake until the nausea subsides.
- C. Come to the clinic immediately for evaluation and treatment.
- D. Monitor the blood glucose every 1 to 2 hours and call if it rises over 150 mg/dL (8.3 mmol/L).
Correct Answer: D
Rationale: Illness can cause blood glucose to rise, so the patient should monitor frequently and report if glucose levels exceed 150 mg/dL.
Which of the following hormones is released from the posterior pituitary gland?
- A. Antidiuretic hormone
- B. Thyroid-stimulating hormone
- C. Parathyroid hormone
- D. Prolactin
Correct Answer: A
Rationale: Antidiuretic hormone (ADH) is released by the posterior pituitary and plays a key role in regulating water balance in the body.