QuestionSBA
QuestionChoice
This is the correct answer. In addition to bone, PTH directly influences calcium metabolism in the kidneys by regulating calcium reabsorption and promoting the excretion of phosphate. PTH helps to conserve calcium and increase its concentration in the bloodstream by enhancing its reabsorption in the renal tubules.
10025385
a
Kidneys
QuestionChoice
Although PTH indirectly influences calcium absorption in the intestines by stimulating calcitriol production, its primary sites of action for calcium regulation are the bones and kidneys.
10025389
e
Intestines
QuestionChoice
The parathyroid gland that produces PTH is located behind the thyroid gland. Despite the close location, the thyroid gland is not involved in calcium metabolism. It only helps to regulate the blood calcium levels, by producing and releasing the calcitonin hormone. It opposes the action of the PTH.
10025387
c
Thyroid gland
QuestionChoice
The vast majority of vitamin D is produced in the skin through exposure to UV light. Activated vitamin D increases calcium absorption. However, PTH does not act on the skin to affect calcium metabolism.
10025388
d
Skin
QuestionChoice
The liver's primary function related to calcium is the synthesis of vitamin D-binding protein and the conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D (calcitriol). Calcitriol is increased by PTH and is essential for calcium absorption in the intestines. Although the liver is involved in the production of calcitriol, which indirectly influences calcium absorption, it is not a direct target of PTH in calcium regulation.
10025386
b
Liver
Concept
Chapter
2693
4371
Calcium levels
Topic
167
Endocrine physiology
17475
A 65 year old woman with recurrent low-impact fractures is assessed in the bone health clinic. She is found to have hypercalcaemia and an elevated plasma parathyroid hormone (PTH) level. The clinician explains that PTH acts upon bones, stimulating the release of calcium and thus weakening them.

Which of the following other organs does PTH act upon directly to influence calcium metabolism?
a