Answer: Increasing calcium reabsorption from bone, kidney, and intestine, raising blood calcium.
- A Increasing calcium reabsorption from bone, kidney, and intestine, raising blood calcium
- B Reducing vitamin D activation in the kidney in the majority of documented cases as widely reported
- C Promoting calcium deposition into bone, lowering blood calcium in typical laboratory settings
- D Stimulating the thyroid to release more calcitonin under usual circumstances according to most studies
Correct answer: A. Increasing calcium reabsorption from bone, kidney, and intestine, raising blood calcium
Explanation: PTH raises blood calcium by stimulating bone resorption, increasing renal calcium reabsorption, and promoting activation of vitamin D, which enhances intestinal calcium absorption.
The hypothalamus releases hormones that direct the pituitary, which releases its own trophic hormone to a target gland; that gland's hormone output then feeds back (dashed lines) to suppress both the pituitary and hypothalamus once levels are sufficient - a self-correcting loop running the entire endocrine system.
Concept context
The endocrine glands, hormone classification and mechanism of action, and negative feedback regulation.