Page 304 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Calcium metabolism
Milk, cheese, eggs
and hard water

Calcium intake Ca Ca
20 [12–35] mmol/day*
Increased
calcium requirements
during pregnancy and nursing

99% Ca Calcium and Phosphate Metabolism I
of total body calcium
Ca
Approx. Kidney
1mmol/day Extracellular
fluid
Ca
Approx.
3mmol/day
Bone Ca Plate 11.13

Calcium excretion in feces in urine
18mmol/day 2mmol/day
(at an intake of 20 mmol/day)
* 1mmol Ca 2+ = 2mEq Ca 2+ = 40mg Ca 2+
B. Factors affecting the blood Ca 2+ C. Calcitriol synthesis
concentration
UV light
Hormones Organs
7-dehydrocholesterol

Previtamin D In the skin
PTH Ca 2+ Gut Cholecalciferol
Raise (vitamin D 3 )
in the diet
Calcitriol Cholecalciferol
(calciol)
1.25 Ca 2+
mmol/L Bone
Lowers Liver
Calcitonin 25-OH-
cholecalciferol
(calcidiol)
Ca 2+
Kidney
Kidney
24,25-(OH) 2 -cholecalciferol
(inactive form)
Calcitriol
2+
Blood Ca concentration (1α,25-(OH) 2 -cholecalciferol 291
(ionized) = active form)
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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