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Calcium Metabolism Quiz
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Which cell type is responsible for the production of parathyroid hormone (PTH)?
- A Follicular cells of the thyroid gland You picked ✕
- B Chief cells of the parathyroid gland You picked ✓
- C Osteoblasts within bone You picked ✕
- D Oxyphil cells of the parathyroid gland You picked ✕
- E Parafollicular cells of the thyroid gland You picked ✕
Correct!
Incorrect
The answer is B: Chief cells of the parathyroid gland
Explanation
Why B is correct
See Calcium Regulation. Option B is correct because chief cells are the primary functional cells of the parathyroid glands, and they make and secrete parathyroid hormone (PTH), a peptide hormone released in response to low blood calcium. The parathyroid glands are usually four small glands sitting on the back of the thyroid gland in the neck, although the number varies. PTH raises blood calcium by acting on bone, the kidney and, through vitamin D activation, the gut. The clinical link is important: the parathyroids lie so close to the thyroid that they can be damaged or removed during thyroid surgery, and PTH deficiency then causes hypocalcaemia, with tingling around the mouth, cramps and in severe cases tetany. Remember that two different gland systems control calcium: the chief cells of the parathyroid raise it, while the parafollicular cells of the thyroid release calcitonin, which lowers it.
- Cell type: chief cells of the parathyroid glands make and secrete parathyroid hormone.
- Action of PTH: raises blood calcium through bone, kidney and, via vitamin D activation, gut.
- Clinical link: thyroid surgery can damage the parathyroids and cause hypocalcaemia.
Why the other options are incorrect
- A. Follicular cells of the thyroid gland: Follicular cells of the thyroid make thyroid hormones, thyroxine and triiodothyronine, which regulate metabolism. They have no role in producing calcium-regulating hormones. They would be the answer if the question asked about thyroid hormone synthesis. Your answer
- C. Osteoblasts within bone: Osteoblasts are bone-forming cells that respond to PTH but do not make it. They are a target of the hormone rather than a source. Their activity is inhibited when PTH rises. Your answer
- D. Oxyphil cells of the parathyroid gland: Oxyphil cells are also found in the parathyroid gland, so this is a tempting choice, but their function is not clear and they are not the hormone-making cells. The primary functional cells are the chief cells. Your answer
- E. Parafollicular cells of the thyroid gland: Parafollicular cells (C cells) of the thyroid make calcitonin, which lowers blood calcium and so opposes PTH. They sit in the thyroid but are not part of the parathyroid. They would be the answer if the question asked about calcitonin. Your answer
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More questions from this set. Start the quiz to answer them and see each explanation.
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1
Which form of calcium in the blood is biologically active and directly able to interact with cells?
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2
A healthy adult has an acute fall in ionised plasma calcium. Which response is most directly responsible for restoring serum calcium in the short term?
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