Question

question 2
which of the following statements regarding the parathyroid glands is not true?
a there are four parathyroid glands located on the dorsal surface of the thyroid gland.
b the parathyroid glands secrete parathyroid hormone.
c parathyroid hormone stimulates bone to absorb more calcium from the bloodstream.
d parathyroid hormone regulates the blood level of calcium.

Explanation:

• Option A: There are usually four parathyroid glands located on the dorsal surface of the thyroid gland. This is a correct anatomical fact.
• Option B: The parathyroid glands secrete parathyroid hormone (PTH). This is a basic function of the parathyroid glands.
• Option C: Parathyroid hormone (PTH) actually stimulates bone - resorbing cells (osteoclasts) to break down bone matrix and release calcium into the bloodstream, not to absorb calcium from the bloodstream.
• Option D: Parathyroid hormone is a key regulator of blood calcium levels. It acts in concert with calcitonin (from the thyroid gland in some species, mainly in fish, and in humans, calcitonin has a relatively minor role compared to PTH in calcium regulation) to maintain calcium homeostasis.

Answer:

C. Parathyroid hormone stimulates bone to absorb more calcium from the bloodstream.