Calcium Homeostasis Flashcards
what is the normal range for blood calcium?
9-11 (or 8.5-10.5) mg/100mL
hypocalcemia causes chief cells of the parathyroid gland to release ____
parathyroid hormone (PTH)
target organs of PTH
bone
kidney
PTH action on bone
increases osteoclasts
what is the effect of PTH on calcium & phosphate absorption in the kidney?
increase Ca absorption
decrease phosphate absorption
(increases phosphate in urine by phosphate buffer system)
PTH in the kidney causes formation of…
1,25 (OH)2 vitamin D3
AKA 1,25 (OH)2 cholecalciferol
AKA calcitriol
what is the effect of calcitriol?
increases Ca and Phosphorus absorption from intestines
hypercalcemia causes parafollicular cells of the thyroid gland to release ____
calcitonin
target organs of calcitonin
bone
kidney
action of calcitonin on bone
increases osteoblasts
action of calcitonin on kidney
decrease Ca absorption
increase phosphate absorption
the kidney impacts absorption of Ca and phosphorus from the intestines in response to…
PTH (low Ca or high phosphorus in blood)
PTH turns on the enzyme ____ and converts…
1-a hydroxylase
25 hydroxycholecalciferol -> 1,25 dihydroxycholecalciferol (vitamin D3 /calcitriol)
what increases the rate of excretion of Ca ions by the kidney?
decrease in plasma level of PTH
secretion of PTH is stimulated by ____
hypocalcemia
function of ____ is increased by elevated PTH concentration
osteoclasts
what is the mechanism of weightlifting increasing bone mass?
mechanical stress on bones increases osteoblast activity
exposure to UV light directly facilitates…
conversion of cholesterol to 25-hydroxycholicalciferol
a patient with renal failure and high vitamin D3 is unable to form…
1,25-dihydroxycholecalciferol in the kidneys
what are 2 ways for the body to get vitamin D3?
- diet
- UV light exposure (7-dehydrocholesterol -> vitamin D3/cholecalciferol)
in the liver, cholesterol is converted to ____
7-dehydrocholesterol
Elevation of serum calcium concentration would cause the release of ____
Calcitonin
