Lecture 20

Question 1

What are the two types of minerals?

Answer 1

Major and Trace.

Question 2

Describe Major Minerals?

Answer 2

Minerals present in amounts larger than 5g (a teaspoon). A pound is about 454g; thus only calcium and phosphorous appear in amounts larger than a pound.

Question 3

Describe trace minerals?

Answer 3

There are more than a dozen trace minerals.

Question 4

Describe the function of iron containing haemoglobin?

Answer 4

Hb is a metalloprotein with heme, and orion porphyrin, attached to the protein moiety. The iron combines with the oxygen in the lungs, where the concentration is high, and releases the oxygen in the tissues where it is needed.

Question 5

Describe the function of iron containing myoglobin?

Answer 5

Within the muscle cell has a function similar to haemoglobin.

Question 6

Describe the function of iron containing cytochromes?

Answer 6

Transfer of electrons and storage of energy through alternate oxidation and reduction of iron (Fe2+ -> Fe 3+).

Question 7

How much iron is recycled daily?

Answer 7

20-25mg iron is recycled daily and used for RBC information.

Question 8

How much iron is required to be absorbed daily?

Answer 8

1-2mg iron is required to be absorbed daily to replace losses.

Question 9

What is the bioavailability of iron?

Answer 9

Low. However it is variable depending on physiological factors and dietary factors.

Question 10

How much iron can we store in our RBC?

Answer 10

2500mg.

Question 11

How much iron can we store in plasma?

Answer 11

4mg.

Question 12

How much iron do we loose in a day?

Answer 12

1-2mg. It is lost through the gut enterocyte.

Question 13

Describe the 1st step of iron recycling?

Answer 13

Transferrin carries iron in blood. Some iron is then delivered to myoglobin of muscle cells.

Question 14

Describe the 2nd step of iron recycling?

Answer 14

Bone marrow incorporates iron into haemoglobin of RBCs and stores excess iron in ferritin (and hemosiderin).

Question 15

Describe the 3rd step of iron recycling?

Answer 15

Iron-Congaing haemoglobin in RBC carries oxygen. Some iron is lost if bleeding occurs.

Question 16

Describe the 4th step of iron recycling?

Answer 16

Liver (and spleen) dismantles RBCs, packages iron into transferrin, and stores excess iron in ferritin (and hemosiderin).

Question 17

Describe the 1st step of iron absorption?

Answer 17

Take iron into the stomach through food.

Question 18

Describe the 2nd step of iron absorption?

Answer 18

Mucosal cells in the SI store excess iron in mucosal ferritin (a storage protein). They’ll only release iron if our body needs it.

Question 19

Describe the 3a step of iron absorption?

Answer 19

If the body does not need iron, iron is excreted in shed intestinal cells.

Question 20

Describe the 3b step of iron absorption?

Answer 20

If the body needs iron, the mucosal ferritin releases iron to mucosal transferrin (transport protein), which hands off iron to another transferrin that travels through the blood to the rest of the body.

Question 21

What happens when RBC life is over?

Answer 21

Macrophages dismantle the RBC and take the iron from the RBC and then release the iron.

Question 22

What is the master regulatory controller?

Answer 22

Hepsidin. Hormone produced by the liver.

Question 23

Where do we get non-heme iron from?

Answer 23

Foods derived from plants.

Question 24

Where do we get heme iron from?

Answer 24

Only foods derived form animal flesh, however they do contain non-heme iron as well.

Question 25

What actors enhance non-heme iron absorption?

Answer 25

1. MPF factor.
2. Vitamin C.
3. Citric acid from foods.
4. Lactic acids from foods.
5. HCl from stomach.
6. Sugars.

Question 26

What factors inhibit non-heme absorption?

Answer 26

1. Phytates - find in wholegrain foods.
2. Fibres.
3. Oxalates - spinach, iron is bound to oxalate and doesn’t allow it be solubilised by the enterocytes.
4. Calcium - bind to non-heme iron.
5. Phosphorus.
6. Polyphenols.
7. Tannins - from tea and binds wiht non-heme iron and prevents it from being absorbed.

Question 27

Where else can you get iron from?

Answer 27

1. Contamination iron - i.e. skillets, iron would leak from the pans.
2. Iron supplements - diagnosed with iron deficiency, will be put on these. Usually 300mg and come with Vitamin C. The problem of this it can cause gut disturbance i.e. constipation or diarrhoea.

Question 28

What is the RDI of iron?

Answer 28

It all depends on the age you are. Iron increases during infancy to 11mg, then decreases then increases during menstruation and pregnancy.

Question 29

What are the 3 stages of iron deficiency in an adult?

Answer 29

1. Depleted storage iron - Serum ferritin drops

Question 30

What happens in our body in iron deficiency?

Answer 30

Always deplete our body iron status first to have enough RBC, so bye he time we are at the stage 3. We have low amounts of iron.

Question 31

What do the RBC look like in iron-deficiency anaemia?

Answer 31

Pale, small RBC. Microcytic anaemia.

Question 32

What is iron vital for?

Answer 32

Myelination. Neuronal growth and differentiation and neurotransmitter regulation.

Question 33

What is the RDI for pregnant woman (aged 14-50yo)?

Answer 33

27mg/d. No routine supplementation in NZ - always take a blood test at first check up. Fe supplements on diagnosis of Fe-def anaemia and under supervision of LMC. The problem is that there are adverse side affects in the gut. A lot of women then stop taking the supplements.

Question 34

What are the significant sources of iron?

Answer 34

Red meats, fish poultry, shellfish, eggs, legumes and dried fruits.