Term
| What are the two main sources of iron in the body? |
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Definition
1. Diet
2. Recycled iron from the breakdown of red blood cells |
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Term
| What are the two classifications of iron in the body? |
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Definition
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Term
| What molecule is organic (heme) iron bound to? |
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Definition
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Term
| Breakdown of heme leads to what product? Excess in this product can lead to what disease? |
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Definition
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Term
| What is non heme iron bound to typically? |
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Definition
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Term
| How does iron storage differ depending on location in the body? |
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Definition
Blood - Bound to transferrin
Cell - Bound to ferritin
Milk - Bound to Lactoferrin
Note: Transferrin receptor binds iron/transferring complex to import iron into the cell |
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Term
| Why can elevated iron levels be toxic? |
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Definition
They can lead to the production of reactive oxygen species
(Can react with hydrogen peroxide to make the hydroxyl radical, which does not have an enzyme capable of dealing with it) |
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Term
| On what scale (units) do we ingest iron daily from our diet? In which form (heme vs. non heme) do we mostly absorb? |
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Definition
1. milligrams
2. Non heme is mostly absorbed through the diet |
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Term
| Describe the cells that absorb iron from diet and how they accomplish this. |
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Definition
1. Crypt cells exist toward the basement membrane
2. These "immature" cells get iron from the bloodstream via the transferrin receptor, whose activity is controlled by the HFE protein. This "programs" the cell to be used to a certain iron level
4. Crypt cell matures eventually and becomes a villus enterocyte
5. Iron now enters the cell slowly from the diet via the DMT1 (Divalent metal transporter)
6. Iron is excreted from the cell into the bloodstream to the ferroportin transporter |
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Term
| Describe the endocystosis of iron by tissues |
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Definition
1. 2 iron molecules bind to the transferrin carrier
2. Loaded carrier binds to the transferrin receptor
3. Receptor is coated with clathrin and endocystozed
4. Vesicle goes to the endosome where the acidic pH (~5) releases the iron from the receptors into the cell
5. Transferrin and receptors are recycled to the surface |
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Term
| In what form is iron when it enters ferritin? when it is stored? when it leaves? |
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Definition
| Enters as Fe++, stored as Fe+++, leaves for use as Fe++ |
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Term
| Explain how aconitase regulates ferritin and transferrin receptor production |
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Definition
Ferritin:
In iron starvation, aconitase binds upstream of the coding region of the mRNA, blocking its translastion. When you have excess iron, iron binds to aconitase and removes it, allowing ferritin to be made
Tf Re:
Iron starvation: Aconitase binds downstrem of the coding region of the mRNA protecting it from degradation
Excess iron: Iron bonds to aconitase, releasing is and allowing mRNA to be chewed up easier, leading to less Tf Re |
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Term
| What is hemochromatosis and what causes it? |
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Definition
| Elevated iron levels in the body. Caused by a breakdown of the absorption transporters of iron in the intestine (they cant limit the amount the absorb properly). Leads to liver, heart, pancreatic failure, must limit iron intake and can treat with transfusion |
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Term
| What is the main role zinc plays in your body? |
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Definition
| Maintain immune system, would healing, cell growth and division |
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Term
| What role does Selenium play in our body? |
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Definition
| Aids enzyme funtion, stimulates antibody production after vaccination, aids male fertility |
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