Iron Hemostasis Flashcards
Large amounts of free iron are toxic to cells, therefore most of it is bound to plasma proteins or storage molecules. Every cell in the body is capable of storing iron. In the cell cytoplasm, iron combines with ????? to form ??????
Apoferritin
Ferritin
Ferritin is the primary protein responsible for safe storage of iron in cells. Smaller quantities of iron are in an an extremely insoluble form called ???????. This is most commonly found in the ???????? of the reticulo-endothelial system. Iron is primarily stored in which organ
hemosiderin
macrophages
liver
Very small amounts of ferritin are found in serum. This is directly related to the amount of iron in macrophages in the ??????
Reticulo-endothelial system
What happens to serum feritin in iron deficiency?
What happens to serum ferittin in iron overload?
Iron overload can lead to tissue damage, causing increased levels of ????????, an inflammatory marker
- decreases
increases
Acute phase protein
What protein is responsible for iron transport in the plasma? What cells produce this? How many binding sites does it havre for iron, and what typical iron saturation levels would you expect to see in the blood?
- Transferrin -formed when iron combies with apotransferrin
- Produces by hepatocytes in liver
- has two binding ites
- Woud expect to see 30% saturation
Excess iron in the blood is deposiyed in what two main places?
- Liver hepatocytes
- Reticuloendothelial cells
Why are women more like to suffer from iron deficiency?
Blood loss from menstruation
What is the daily iron requirement in mg? How much does a typical Western diet contain?
1-2mg
15-20m/g
Haem iron and non-haem iron are found in what food sources?
Haem: red meat
non-heam: white meat, vegetables, cereals
RBCs circulate for 120 dys, then they are digested, and broken down by the ?????????? Iron released from the RES will enter the plasma and once again bound transferrin. The RES stores around ?????of iron in the form ferritin/haemosiderin.
Macrophaes of the reticuloendothelial system
500mg
State the only way in which humans regulate iron balance
By regulating how much iron is absorbed.
Where does iron absorption occur?
Duodenum
Haem iron is very easily absorbed by duodenal enterocytes. Non-haem iron, in order to be released from foodsuffs, requires ???? digestionand ???????? enzymes in stomach.
- acid
- proteolytic enzymes
Non haeme iron must be reduced from the ?????? form to the ????? form of iron. Which enzyme does this in the duodenum? What vitamin plays a role in this process?
Ferric (Fe3+) must be transformed into Ferrous (Fe2+)
Duodenal Cytochrome B1
Vitamin C
What transporter is ferrous iron passed through to get from intestinal lumen into the enterocyte
- DMT1 (DMT1 expession is upregulated during iron deficiency)
In the basolateral membrane of the enterocyte, iron is exported to circulation by ??????, which is also crucial for the release of iron from ?????????
Ferroportin
macrophages of the reticuloendothelial system
Iron is delivered to tissues by binding to what receptor? The highest concentration - 80%- of transferin receptors are found on what cells? The next most concentrated area of transferin receptors is?
Transferrin receptor - which then uptakes the iron by receptor mediated endocytosis.
RBCs
Liver
Describe the difference between anemic blood and normal blood
- anemic cells are very pale, smaller (hypochromic and microcytic)
Heamatinic defeiciency in coleliac disease is common (this means deficiency in Iron, folate, B12. Order them in terms which one is most likely to be affected from coeliac. A haemanitic deficiency refers to a substance required for the formation of red blood cells.
Most likely: Folate
Next: Iron
Least: B12
Blood film in coeliac disease. Can show various haematinic deficienices in folate, ferritin. Patients can also be hyposplenic (an absent spleen like, because the spleen is known to atropy in coeliac disease. - what would you expect to see for this?
Hyposplenism, which may be a complication of chronic folate deficiency, the result of excessive loss of lymphocytes through the damaged GI tract or related to the mucosal lesion,[135] is a well-documented complication of celiac disease in historical case series
- “target” like appearance
- Contain Howell Jolly bodies
- Also can have an “irregularly contracted appearance”, basically dont have normal circular biconcave shape
At the level of the genome, what gene is cruical for hepcidin synthesis.
HFE - diagram just for illustration
hereditary haemochromatomois in what sex? What factors make it less likely for females to be affected? WHat race in particular is at higher risk?
Men
Periods, babys
Celts - 1 in 8 re carriers, heterozygous C282Y
none of this should be hugely surprising. The disease HHC will lead to accumualtion of iron.
study
