Calcium Flashcards
What inhibits the uptake of calcium?
Oxalate and phytate
What tissue do osteogenic cells originate from?
Mesenchymal
What do osteoprogenitors and osteoblasts lay down?
Osteoid in epiphysis
Collagen
What forms an osteoclast?
Many monocytes
Acid and lysosomes
What do osetocytes do?
Exchange waste and nutrients
How does vitamin D impact the epiphyseal plate?
Stop the cells dividing in the proliferative zone so they differentiate forming the hypertrophic zone where the cells then die and are replaced by bone
Where are Ca receptors?
Thyroid
Parathyroid
Bone
Renal tubules
What do the receptors release?
Parathyroid hormone and calcitonin
What will calcitonin cause?
Stop calcium being reabsorbed to give osteoblasts time to catch up with the osteoclast activity
Increase renal excretion
What does vitamin D do?
Stimulate more Ca reabsorption in intestine and kidney
Increase osteoclast activity
What does PTH do?
Stimulate Ca reabsorption in kidney
Increase osteoclast activity
Where is Ca actively and passively reabsorbed in the kidneys?
DCT and upper CD
PCT and ascending loop
How is vit D involved in the Ca uptake path in cells?
It increases the number of Ca channels taking it into the cell and the amount of binding protein made to attach to the Ca to transport it across the cell to then make it exit
What is photoconversion?
Sun converts x in skin to pre vit D which the liver takes up and is then moved to the kidneys to form vit D using an enzyme
What stimulates the enzymes to convert pre vit D to vit D?
PTH
