Y1S2 008 II Biochem Calcium Metabolism Disorders: Overview and Functions

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Questions and Answers

What is the primary function of calcium in the development of bone and teeth?

Coenzyme for coagulation factors
Present as calcium phosphate (correct)
Intracellular second messenger for secretion of some hormones
Transmission of nerve impulses

What percentage of calcium in the plasma is protein-bound?

40% (correct)
20%
50%
30%

What is the term for the mechanism by which the body maintains adequate calcium levels?

Calcium metabolism
Calcium homeostasis (correct)
Calcium regulation
Calcium balance

What is the percentage of ionized calcium in the plasma?

50% (C) Signup and view all the answers

What is the role of calcium in the transmission of nerve impulses?

Control of excitability (B) Signup and view all the answers

What is the term for the movement of calcium between extracellular fluid, gut, bone, and kidney?

Calcium balance (D) Signup and view all the answers

What is the primary function of parathyroid hormone (PTH) in the body?

To regulate the concentration of calcium in the ECF (B) Signup and view all the answers

What is the typical location of the parathyroid glands in the body?

Posterior to the thyroid gland (D) Signup and view all the answers

What is the molecular weight of parathyroid hormone (PTH)?

9425 Da (C) Signup and view all the answers

What is the half-life of intact PTH in the blood?

3-4 minutes (B) Signup and view all the answers

What is the region of the PTH molecule required for PTH receptor binding in target cells?

N-terminal 1-34 amino acid sequence (D) Signup and view all the answers

What is the number of amino acids in the precursor molecule of PTH?

115 amino acids (D) Signup and view all the answers

What is the pattern of plasma PTH levels throughout the day?

Highest in the early morning hours and lowest at 9 a.m. (C) Signup and view all the answers

What is the primary effect of PTH on plasma [Ca2+]?

Increase ionized calcium (B) Signup and view all the answers

Which receptor does PTH bind to in the central nervous system?

Parathyroid hormone 2 receptor (C) Signup and view all the answers

What is the net effect of PTH on glomerular filtration rate (GFR)?

Decrease GFR (A) Signup and view all the answers

What is the result of PTH's action on the distal tubule?

Increased excretion of bicarbonate (B) Signup and view all the answers

What is the time frame of PTH's delayed action on bone?

Days and weeks (B) Signup and view all the answers

What is the primary cause of hypercalcemia in primary hyperparathyroidism?

Combined effects of PTH-induced bone resorption and intestinal calcium absorption (A) Signup and view all the answers

What is the most common presenting complaint in primary hyperparathyroidism?

Renal stones (B) Signup and view all the answers

What is the underlying mechanism of secondary hyperparathyroidism?

Excessive secretion of PTH in response to hypocalcemia (A) Signup and view all the answers

What is the result of the deposition of calcium in the kidney tubules in primary hyperparathyroidism?

Impaired renal function (A) Signup and view all the answers

What is the underlying cause of hyperphosphatemia in secondary hyperparathyroidism?

Damaged renal parenchyma (C) Signup and view all the answers

What is the characteristic laboratory finding in primary hyperparathyroidism?

Hypercalcemia and hypophosphatemia (C) Signup and view all the answers

What is the effect of 1:25-DHCC on 25-HCC?

It stimulates the hydroxylation of 25-HCC (C) Signup and view all the answers

What is the effect of PTH on 1α-hydroxylase activity?

It stimulates the activity of 1α-hydroxylase (B) Signup and view all the answers

What is the role of calbindin-D in the gut?

It promotes the absorption of calcium and phosphate from the gut lumen (B) Signup and view all the answers

What is the effect of calcitriol on osteoclasts?

It stimulates the activity of osteoclasts (D) Signup and view all the answers

What is the role of alkaline phosphatase in bone formation?

It promotes the formation of new bone (A) Signup and view all the answers

What is the significance of serum osteocalcin levels?

They are a marker of bone formation and turnover (C) Signup and view all the answers

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