Question 1

Which of the following best describes the role of bones in mineral homeostasis?

Accepted Answer

Bones act as reservoirs for inorganic ions, especially calcium and phosphate, contributing to osmotic balance and physiological processes.

Question 2

Approximately what percentage of the body's calcium is deposited in the skeleton?

Accepted Answer

About 99%

Question 3

A patient presents with muscle spasms and abnormal nerve impulses. Laboratory tests reveal a 40% decrease in blood calcium concentration. Which physiological process is most likely affected?

Accepted Answer

Neuron and muscle function

Question 4

Which equation correctly represents the formation of hydroxyapatite, the major mineral component of bone?

Accepted Answer

$$10Ca^{2+} + 6PO$$_$$4^{3-} + 2OH$$^- \rightarrow Ca_{10}($$PO_4)_6(OH)_2$

Question 5

Which hormone is secreted by the parathyroid glands and increases blood calcium levels by stimulating osteoclast activity?

Accepted Answer

Parathyroid hormone (PTH)

Question 6

What is the effect of calcitonin on bone tissue?

Accepted Answer

Inhibits osteoclast activity, promoting deposition of calcium into bone matrix

Question 7

Which of the following best explains why calcium ions ($$Ca^{2+}) $$are important for muscle contraction?

Accepted Answer

They bind to proteins, changing their function and allowing contraction to occur.

Question 8

If a patient has decreased parathyroid hormone (PTH) secretion, which of the following would most likely occur?

Accepted Answer

Decreased osteoclast activity and reduced blood calcium

Question 9

Which process is directly enhanced by calcitriol in the intestines?

Accepted Answer

Calcium absorption

Question 10

A patient with hypercalcemia (high blood calcium) is likely to have increased secretion of which hormone?

Accepted Answer

Calcitonin

Question 11

Which of the following best describes the effect of parathyroid hormone (PTH) on the kidneys?

Accepted Answer

It stimulates the release of calcitriol, increasing calcium reabsorption.

Question 12

Which of the following is a direct result of osteoclast activity in bone tissue?

Accepted Answer

Release of calcium and phosphate into the bloodstream

Question 13

If the concentration of blood calcium varies by more than 35%, which physiological functions are most likely to be impaired?

Accepted Answer

Neuron and muscle function

Question 14

Which of the following equations represents the ionic dissociation of calcium in aqueous solution?

Accepted Answer

$$Ca \rightarrow Ca$$^{2+}$$ + 2e^-$$

Question 15

Which hormone decreases blood calcium levels by inhibiting calcitriol release and calcium reabsorption in the kidneys?

Accepted Answer

Calcitonin

Question 16

A patient is found to have low bone density and frequent fractures. Which of the following is the most likely cause?

Accepted Answer

Excessive release of calcium from bone into the blood

Question 17

Which of the following best describes the relationship between calcium and phosphate in bone?

Accepted Answer

They form a crystal lattice that provides strength to bone.

Question 18

Which of the following is NOT a function of calcium in the body?

Accepted Answer

Synthesis of hemoglobin

Question 19

Which of the following statements about daily fluctuations in blood calcium concentration is correct?

Accepted Answer

Normal daily fluctuations are less than 10%.

Question 20

Which of the following best explains the effect of calcitonin on the intestines?

Accepted Answer

It decreases calcium absorption by reducing PTH and calcitriol.

Calcium Regulation in the Body: The Role of Bone

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