Iron Cycle

Question 1

What is the available iron in the body bound to?

Answer 1

• Haemoglobin
• Myoglobin
• Enzymes
• Transferrin

Question 2

What are the two types of Stored Iron in the body?

Answer 2

• Ferritin (soluble)
• Haemosiderin (insoluble)

Question 3

What is Haemosiderin?

Answer 3

• Aggregates of clumped ferritin particles
• Accumulates through macrophages in the Liver (Kupffer cells), spleen and marrow

Question 4

What is the Pathophysiology behind Iron Cellular Uptake?

Answer 4

• Fe3+ is typically bound to transferrin in the blood
• Transferrin binds to the transferrin receptors
• Fe3+ is then reduced to Fe2+
• Fe2+ is transported to the cytosol via DMT1
• Once in cytosol, Fe2+ is stored in ferritin, exported or taken up via the mitochondria

Question 5

Where does iron recycling occur?

Answer 5

• Old RBC are engulfed by macrophages
• Typically Splenic macrophages + Kupffer cells in Liver

Question 6

Where are RBC made?

Answer 6

• In the bone marrow via Erythropoiesis