Physiology: absorption of Ca & Fe Flashcards
1
Q
how is Ca in chyme mainly absorbed
A
by active absorption
2
Q
what is active Ca absorption regulated by
A
1,25-dyhydroxyvitamin D3 and parathyroid hormone
3
Q
describe the action of 1,25-dihydroxyvitamin D3
A
increase the expression of Ca channel and Ca ATPase
therefore increasing Ca absorption
4
Q
what form of Fe is mainly in the diet
A
Fe3+
5
Q
what is the only from of Fe that can be absorbed
A
Fe2+
6
Q
what is reduction of Fe3+ to Fe2+ promoted by (4)
A
HCl in stomach, vitamin C, ferric reductase and gastroferrin
7
Q
what does some Fe2+ combine with to be stored, and what is it stored as
A
combines with cytoplasmic apoferritin
stored as ferritin
8
Q
describe how the influx of Fe2+ via DMT1 is done
A
by transport by mobilferrin to ferroportin-1, that mediates efflux
