Untitled Deck Flashcards
What effect does PTH have on the kidneys?
Inhibits phosphate reabsorption
Which form of vitamin D is the biologically active form?
1,25-dihydroxyvitamin D (calcitriol)
Calcitonin is secreted by which of the following cells?
Thyroid parafollicular cells (C cells)
Which hormone increases calcium absorption in the intestine?
Calcitriol (vitamin D)
PTH increases serum calcium levels by acting on:
Bones, kidneys, and intestines
What is the effect of calcitonin on bone?
Inhibits osteoclast activity
Which enzyme is activated by PTH in the kidney to produce calcitriol?
1α-hydroxylase
Which condition is associated with hypocalcemia due to vitamin D deficiency?
Rickets
What triggers the release of PTH from the parathyroid gland?
Low serum calcium
Which of the following inhibits PTH secretion?
High vitamin D (calcitriol)
In the bone, PTH indirectly stimulates osteoclast activity by:
Stimulating osteoblasts to release RANKL
Which of the following is not a function of calcitriol?
Stimulates renal calcium excretion
Chronic kidney disease can cause hypocalcemia due to:
Impaired activation of vitamin D
The role of phosphate in calcium regulation is best described as:
Binds calcium, lowering free calcium levels
Which hormone acts as a counter-regulatory hormone to PTH?
Calcitonin
What is the effect of PTH on phosphate levels in the blood?
Decreases phosphate reabsorption
Which of the following would most likely be elevated in primary hyperparathyroidism?
Serum calcium
Vitamin D requires which organs for full activation?
Skin, liver, and kidney
A deficiency of calcitonin would most likely lead to:
Minimal physiological impact in adults
