6 Questions
Which of the following hormones is primarily responsible for increasing calcium absorption in the small intestine?
Calcitriol
What is the primary effect of parathyroid hormone on the kidneys?
Increase calcium reabsorption
Where are the parathyroid glands located?
Behind the thyroid gland
Which hormone is released when blood calcium levels fall?
Parathyroid hormone (PTH)
How does PTH stimulate an increase in blood calcium levels via the bones?
It stimulates bone resorption
What is the role of activated vitamin D in calcium regulation?
It increases calcium absorption in the intestines
Study Notes
Hormones Regulating Calcium Levels
- Three hormones regulate the level of calcium in the blood: parathyroid hormone (PTH), calcitriol (1, 25 dihydroxyvitamin D), and calcitonin.
Parathyroid Hormone (PTH)
- Produced by the parathyroid glands, four small, pea-sized glands located behind the thyroid gland.
- Released when the level of calcium in the blood falls.
- Increases the level of calcium in the blood through three mechanisms:
- Stimulates bone resorption, releasing calcium stored in the bone.
- Increases calcium reabsorption in the kidneys, reducing calcium loss through urine.
- Stimulates the activation of vitamin D in the kidneys.
Vitamin D Activation
- Activated vitamin D (calcitriol) is essential for the small intestine to absorb more calcium from the diet into the bloodstream.
Learn about the three hormones involved in regulating the level of calcium in the blood, including parathyroid hormone, calcitriol, and calcitonin.
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