The Student Room Group

Iron Homeostasis

Why do transferrin receptors increase when iron is scarce, and you want less storage?

I would think that you don't want a lot of receptors because that would cause iron to go into cells and out of the blood right?

Thanks!
Original post by DivinCloud03
Why do transferrin receptors increase when iron is scarce, and you want less storage?

I would think that you don't want a lot of receptors because that would cause iron to go into cells and out of the blood right?

Thanks!


I havent started this topic yet but iron is the prosthetic group of haemoglobin (in its quaternary structure) so it doesn’t leave the blood. The only time there is a loss of iron is if someone is menstruating/bleeding or anaemic.
i hope this helps.
Original post by JA03
I havent started this topic yet but iron is the prosthetic group of haemoglobin (in its quaternary structure) so it doesn’t leave the blood. The only time there is a loss of iron is if someone is menstruating/bleeding or anaemic.
i hope this helps.



thanks for the reply!

I think we're probably learning this at different levels, just because i mean when iron leaves the blood to make red blood cells etc
Original post by DivinCloud03
Why do transferrin receptors increase when iron is scarce, and you want less storage?

I would think that you don't want a lot of receptors because that would cause iron to go into cells and out of the blood right?

Thanks!

Hello,

Transferrin [which can contain up to two atoms of iron] carries iron to cells that express transferrin receptors [TfRs]. The main cells here are erythroblasts [precursors] where the iron is used for the synthesis of haemoglobin.

When red cells die [average lifespan is about 120 days], they are broken down in macrophages, the iron from the Hb enters the plasma and is the predominant source of iron on transferrin.

Coming specifically to your Q, any receptors in the body [in general], when starved of their agonist [stimulating substance here transferrin [in combination with iron]] EITHER become more sensitive to the agonist [called sensitization] OR the receptor levels increase.in order to compensate for the reduced effect, whatever that may be.

An analogy in physiology/pharmacology occurs when e.g. a neurotransmitter is reduced in quantity, so that the effect normally produced by that transmitter is reduced; for the system to recover/compensate for this reduction, sensitization occurs in one of the above ways.

The corollary i.e. desensitization when a transmitter is produced in excess can also occur - this is one reason why drug addicts keep requiring more and more of the addictive drug over time since e.g. opiate receptors are reduced with increasing doses of heroin.

I appreciate that the comparison is somewhat different, but I hope this clarifies the principle.

Be safe!
M

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