Which of the following statements correctly describes the role of parathyroid hormone?
a. Parathyroid hormone regulates the metabolic rate.
b. Parathyroid hormone increases the blood calcium ion concentration.
c. Parathyroid hormone decreases the blood sodium ion concentration.
d. Parathyroid hormone causes water retention by the kidneys.

검증된 단계별 안내

Understand the role of parathyroid hormone (PTH): Parathyroid hormone is secreted by the parathyroid glands and plays a critical role in regulating calcium homeostasis in the body.

Review the physiological effects of PTH: Parathyroid hormone increases blood calcium levels by stimulating osteoclast activity in bones (breaking down bone tissue to release calcium), enhancing calcium reabsorption in the kidneys, and promoting activation of vitamin D to increase calcium absorption in the intestines.

Eliminate incorrect options based on PTH's function: a) PTH does not regulate metabolic rate; this is primarily controlled by thyroid hormones like thyroxine. c) PTH does not directly affect sodium ion concentration. d) PTH does not cause water retention; this is regulated by hormones like antidiuretic hormone (ADH).

Focus on the correct option: b) PTH increases blood calcium ion concentration, which aligns with its primary function in calcium homeostasis.

Conclude the reasoning: The correct description of parathyroid hormone's role is its ability to increase blood calcium ion concentration, ensuring proper functioning of muscles, nerves, and other physiological processes.

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주요 개념

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Parathyroid Hormone (PTH)

Parathyroid hormone is a peptide hormone produced by the parathyroid glands that plays a crucial role in regulating calcium levels in the blood. It is released in response to low blood calcium levels and acts to increase calcium concentration by stimulating bone resorption, enhancing intestinal absorption of calcium, and promoting renal reabsorption of calcium.

Calcium Homeostasis

Calcium homeostasis refers to the mechanisms that maintain stable levels of calcium in the bloodstream, which is vital for various physiological functions, including muscle contraction, nerve transmission, and blood clotting. PTH is a key regulator in this process, working alongside calcitonin and vitamin D to ensure that calcium levels remain within a narrow range.

Effects of PTH on the Kidneys

Parathyroid hormone affects the kidneys by increasing the reabsorption of calcium and promoting the excretion of phosphate. This action helps to elevate blood calcium levels while simultaneously managing phosphate levels, which is essential for maintaining overall mineral balance in the body.