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Calcium Regulation and Hormonal Control

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Questions and Answers

What triggers the secretion of parathyroid hormone (PTH)?

A decrease in ionized Ca2+ (correct)

External calcium intake

Consistent levels of ionized Ca2+

An increase in ionized Ca2+

Which process is activated by PTH in the bones?

Bone ossification

Bone remodeling

Bone calcification

Bone resorption (correct)

What effect does PTH have on the kidneys?

Reduces vitamin D activation

Enhances tubular reabsorption of Ca2+ (correct)

Stimulates bone formation

Increases calcium excretion

What is the action of PTH on vitamin D?

<p>Stimulates renal production of active vitamin D (D)</p> Signup and view all the answers

What hormone is known for opposing the effects of PTH in calcium regulation?

<p>Calcitonin (B)</p> Signup and view all the answers

Flashcards

Parathyroid hormone (PTH)

A hormone that increases blood calcium levels by stimulating bone resorption and calcium reabsorption in the kidneys.

Bone resorption

The process where bone cells break down bone tissue, releasing calcium into the bloodstream.

Vitamin D

A hormone that increases calcium absorption in the intestines, indirectly increasing blood calcium levels.

Calcitonin

A hormone that decreases blood calcium levels by inhibiting bone resorption.

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Tubular reabsorption of calcium

The process where calcium is reabsorbed back into the bloodstream from the kidneys.

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Study Notes

Calcium Regulation

Three hormones (PTH, vitamin D, calcitonin) regulate serum calcium (Ca2+) levels.
Their secretion rate changes in response to ionized Ca2+ levels.
Parathyroid hormone (PTH) secretion increases when ionized Ca2+ decreases, and vice versa.
PTH affects bone and kidneys.
In bone, PTH activates osteoclasts, causing bone resorption and releasing Ca2+ into the extracellular fluid (ECF).
In kidneys, PTH increases tubular reabsorption of Ca2+ ions, thus conserving calcium.
PTH also stimulates the kidney to produce active vitamin D.

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Description

This quiz delves into the regulation of serum calcium levels through three key hormones: PTH, vitamin D, and calcitonin. It explores their interactions, responses to ionized Ca2+ levels, and the effects on bones and kidneys. Test your understanding of these critical physiological processes.