Iron Metabolism Flashcards
What is iron used for in the body?
– Transports and stores oxygen
– Integral part of many enzymes
including energy metabolism, neurotransmitter production, collagen formation and immune system function
Why is iron content in the body carefully controlled?
Have no mechanism for excreting iron – must maintain a fine balance between absorption and loss
Name the sites containing active iron in the body
��-- Haemoglobin �-- Myoglobin: oxygen reserve in muscles ��--Tissue Iron: enzyme systems, cytochromes ��-- Transported iron-’serum iron’
Give two inactive stores of iron
�Ferritin – soluble
��Haemosiderin – Macrophage iron, Insoluble
Where do you find the majority of iron in the body?
Most in haemoglobin
Stores of iron (liver)
Less in myoglobin
Where is haem iron and non-heam iron found in the diet?
Haem iron – meat
Non-haem iron – cereal and vegetables
What are the two form of iron and which is the correct form to be absorbed by the body?
Fe2+ – ferrous form in meat, easier to absorb
Fe3+ – ferric form in veg and cereals must be reduced by stomach acid to be absorbed
Where does the majority of iron absorption take place?
What facilitates this in the apical surface?
Duodenum and upper jejunum by enterocytes (epithelial cells in jejunum and duodenum)
Transferrin brings two Fe molecules in per transferrin
What protein exports iron out of the blood?
ferrroportin
Describe the process of iron absorption into enterocytes
Stomach acid reduces Fe3+ to Fe2+
Transferrin transports two Fe2+ into enterocytes by endocytosis. Can be stored in RBC as ferritin.
Then enters blood by ferroportin, where it is transported to the liver for storage or used by Hb
What affect does vitamin C have on iron absorption?
Enhances iron absorption
How is iron taken into red blood cells?
by binding of Iron-transferrin complex to transferrin receptor (TfR)
Erythroid cells contain the highest number of TfRs
What can be used as a good level of functional iron levels?
soluble TfR (sTfR) is a good indicator of functional iron levels
What does the regulation of iron absorption depend on?
dietary factors, body iron stores and erythropoiesis
What are the major mechanisms for the control of iron absorption?
Transporter regulation (can be up or down regulated)
Receptor expression
Crosstalk between epithelial cells and macrophages (other cells)
Hepcidin – tissue derived factor