Question 12 of 13

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In iron metabolism:

1. iron stored in liver cells is transported across cell membranes in the ferrous state.

2. the major plasma transport protein for iron is hemosiderin.

3. in the form of ferritin, iron may accumulate in mucosal cells of the duodenum.

4. nearly all iron in the diet is absorbed and any excess secreted in the feces.

A. 1, 2 and 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All of the above

The correct answer is (B).

Comments:

1. It is stored in the iron (III) state, and must be reduced to the iron (II) state prior to transport.

2. Transferrin is the major iron transport protein.

3. Ferritin is an intracellular iron binding (storage) protein.

4. Excess is certainly excreted, but it is never absorbed by the body. Uptake by the intestinal mucosal cells occurs, but in the iron-replete state these iron-rich cells slough. The iron does appear in the feces.

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Last modified 1/5/95