39 - Metabolism and biological role of iron. Mechanisms of absorption of heme- and non-heme iron. Iron-binding and iron-storage proteins – transferrin, transferrin receptors, ferritin. Regulation – hepcidin.

sections

• iron basic info

• iron homeostasis

• iron metabolism

• proteins + mechanisms for iron metabolism

• non heme containing proteins

• hepcidin

• iron basic info

• function = metabolism of oxygen

• forms → Fe 2+/ Fe 3+

• consumed through diet

• iron homeostasis

1. hepcidin levels too high

2. decrease serum iron due to trapping in macrophage + liver cells

3. decreased gut absorption

4. decreased iron concentration in plasma

• iron metabolism

1. iron absorbed through diet, transported through transferrin stored in feritin

2. Used for synthesis of cytochromes, some enzymes, haemo + myoglobin

3. Lost through bleeding, sweat, urine, faeces

• proteins + mechanisms for iron metabolism

• absorbed iron used in bone marrow for erythropoiesis

• iron oxidised to Fe 3+ and absorbed in duodenum

• Incorporates protoporphyrin to make heme (haemoglobin - transport O2, Myoglobin - storage of O2)

• non heme containing proteins

• Ferritin - iron stored in liver is bound to ferritin

• Transferrin - bind and transports iron, transferrin receptons transports iron into cell, regulated by intracellular iron con feedback

• hepcidin

• key regulator

• hepcidin deficiency targets duodenum

• duodenal absorption increases, splenic iron released into circulation

• iron conc in plasma increases

• restoration of iron balance