Iron Flashcards
Where in the body is iron absorbed?
The small intestine
How is iron absorbed in the body?
Across enterocytes
What can increase absorption of iron?
Vitamin C (due to the acid)
What can decrease absorption of iron?
Tea. (Precipitates iron)
How is iron transported around the body?
Transferrin.
How is iron absorbed into a cell?
Transferrin receptors on the cell surface.
Erythrocytes have the most receptors.
How does the body sense dietary levels of iron?
Villi on the enterocytes.
How can the body control iron levels?
Expression of receptors.
Regulation of transporters.
Hepcidin protein.
iron cannot be excreted from the body
What does hepcidin protein do?
Extra point - What would happen if it was over active?
It is a negative regulator of iron absorption.
Extra point - over activity leads to iron deficiency.
Where is hepcidin produced and excreted?
Produced in the liver. Excreted in the kidneys.
What are the sources of iron for the body?
80% recycled from the body.- macrophages breakdown red blood cells to extract the iron.
The diet.
What are the 2 forms of iron in the diet?
Haem form and non haem form.
What are the sources of haem form iron in the diet?
Meat and fish.
What are the sources of non haem form iron in the diet?
Cereals and pulses.
Does the body prefer haem or non haem iron? And why?
Prefers haem iron as it is already in the ferrous structure which is preferred. It is also easier to absorb.
Non haem iron has to be converted to this structure before it can be used.
Why is iron essential to the body?
Part of enzymes.
Transport/stores O2.
What are the 2 forms iron can be stored in?
Ferritin - soluble.
Haemosiderin - insoluble - in macrophages.
Where can you find active iron in the body?
In (mainly) haemoglobin and myoglobin.
Why is excess iron dangerous?
It interacts with the lipid bilayer of cells to make lipid radicals.
How can you test for excess iron?
Genetic tests (if genetic issue)
Venesection - note the levels of iron removed
Raised levels of serum ferritin (due to increased storage of iron.)
What is hemochromatosis?
A disorder where there is iron excess leading to end organ damage.
What are the causes of hemochromatosis?
Genetic - autosomal recessive. Group of disorders, mot common is a mutation in the HFE gene.
Too much iron can be given eg from repeated transfusions. (Gradual build up of iron.)
What is the threshold at which iron levels become damaging within the body?
10-15g
Give one example of an Iron chelating agent that delays, but doesn’t stop the effects of iron?
Desferrioxamine - has negative side effects.
