Iron

Question 1

Where in the body is iron absorbed?

Answer 1

The small intestine

Question 2

How is iron absorbed in the body?

Answer 2

Across enterocytes

Question 3

What can increase absorption of iron?

Answer 3

Vitamin C (due to the acid)

Question 4

What can decrease absorption of iron?

Answer 4

Tea. (Precipitates iron)

Question 5

How is iron transported around the body?

Answer 5

Transferrin.

Question 6

How is iron absorbed into a cell?

Answer 6

Transferrin receptors on the cell surface.

Erythrocytes have the most receptors.

Question 7

How does the body sense dietary levels of iron?

Answer 7

Villi on the enterocytes.

Question 8

How can the body control iron levels?

Answer 8

Expression of receptors.
Regulation of transporters.
Hepcidin protein.
iron cannot be excreted from the body

Question 9

What does hepcidin protein do?

Extra point - What would happen if it was over active?

Answer 9

It is a negative regulator of iron absorption.

Extra point - over activity leads to iron deficiency.

Question 10

Where is hepcidin produced and excreted?

Answer 10

Produced in the liver. Excreted in the kidneys.

Question 11

What are the sources of iron for the body?

Answer 11

80% recycled from the body.- macrophages breakdown red blood cells to extract the iron.
The diet.

Question 12

What are the 2 forms of iron in the diet?

Answer 12

Haem form and non haem form.

Question 13

What are the sources of haem form iron in the diet?

Answer 13

Meat and fish.

Question 14

What are the sources of non haem form iron in the diet?

Answer 14

Cereals and pulses.

Question 15

Does the body prefer haem or non haem iron? And why?

Answer 15

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.

Question 16

Why is iron essential to the body?

Answer 16

Part of enzymes.

Transport/stores O2.

Question 17

What are the 2 forms iron can be stored in?

Answer 17

Ferritin - soluble.

Haemosiderin - insoluble - in macrophages.

Question 18

Where can you find active iron in the body?

Answer 18

In (mainly) haemoglobin and myoglobin.

Question 19

Why is excess iron dangerous?

Answer 19

It interacts with the lipid bilayer of cells to make lipid radicals.

Question 20

How can you test for excess iron?

Answer 20

Genetic tests (if genetic issue)
Venesection - note the levels of iron removed
Raised levels of serum ferritin (due to increased storage of iron.)

Question 21

What is hemochromatosis?

Answer 21

A disorder where there is iron excess leading to end organ damage.

Question 22

What are the causes of hemochromatosis?

Answer 22

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.)

Question 23

What is the threshold at which iron levels become damaging within the body?

Answer 23

10-15g

Question 24

Give one example of an Iron chelating agent that delays, but doesn’t stop the effects of iron?

Answer 24

Desferrioxamine - has negative side effects.

Question 25

What is one natural process where iron deficiency is likely?

Answer 25

Pregnancy.

Question 26

What tests could you do to confirm iron deficiency?

Answer 26

Low serum ferritin. (BUT an increase also indicates many other things eg alcoholism, liver disease and infection.)
Presence of pencil shaped cells.
Red blood cells with a small mean volume. (They’re small)
Low levels of haemoglobin.
Low serum iron.