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HUN3226 Exam 2IronDistribution in the body- Fe essential to life because it is central in heme which carries oxygen to all living cells - Females 2.5 g , Males 4g  Male 70kg distribution- Hemoglobin 2g( can vary)- Storage(hemosiderin, ferritin) 1g( can vary)- Tissue Iron(Mg)o Myoglobin 130mgo Enzyme iron 8mgo Labile iron pool 80mg Rapid turnover not found in 1 locationo Transferrin 3mg  Transferring protein of iron Hemoglobin- transports oxygen - Heme- organic ring (porphyrin) with Fe in the middle o Heme stores oxygen stored in cellular level - 4 Hemes make a hemoglobin Myoglobin- has same structure as Hemoglobin but only 1 heme enclosed in 1 peptide chainStorage:- Iron is stored in liver, spleen, and bone marrowo About 25-30% stored as Ferritin and hemosiderin in the liver Males store 1g iron Females 300mg iron ( this is a basis for the RDAs) - Due to menstruation cycle o Ferritin is a ball shaped protein, the interior of which can hold about 4500 Fe atoms Small amounts of ferritin are in plasma and reflect storage pools, therefore serum ferritin is analyzed for the iron status o Hemosiderin- second storage form of iron Major Functions:- Oxygen transport and storage in hemoglobin and myoglobin (structure)- Part of enzymes that are involved in the electron transport chain and immune system(catalytic functions)o Krebs cycle enzymeso Enzymes used by plants in photosynthesiso Various plant enzymes used in legumes for nitrogen fixationNotes on Dietary Fe- Fe intake in US between 10-30mg/day, depending on meat consumption - 1989 10-15mg/day back then for men and women- 2001 RDA 8mg for me and older women, 18mg for childbearing age women - In the last 25 years meat production has decreased o 1000kcal diet 5-7mg/day of iron on averageo Therefore mixed 2000kcal diet has around 12mg of iron - We would need to consume over 3000kcal for women to get the right amount of iron and most men eat around that amount and have too much iron - Iron from exogenous to the foodso From iron pots and pans/ water sources o Africa Overload of iron from brewing beer in iron - Fe in food is in 2 forms heme and nonhemeo Heme- dietary meat source  Myoglobin from muscle  Hemoglobin from blood o Non heme- form iron salts  Non meat sources vegies and grainso To be utilized  Fe must be released from various components by HCI from the stomach and proteases from the small intestine o Therefore gastric juices ( acid) and Fe absorption are positively related ( with low gastric acid Fe absorption is low) Absorption- Fe absorption is most efficient in the upper duodenum, although it can occur throughout the small intestine - Average person absorbs 5-10-15% of total iron intake ( this means men 1mg/day females 2mg/day) o Heme- is hydrolyzed from the protein( globin) part and absorbed as such metalloporphyrino Non heme- Fe must be released from food components  Fe is primarily oxidized, Fe+++ or Ferrin form - This is poorly soluble form of iron is difficult to absorb  In a healthy stomach the acid will reduce this iron Fe+++ to Fe++ or its reduced state to be absorbed more readily o Effecting absorption Patients with achlorhydria or insufficient acid or post gastrectomy, those taking antacids, acid blockers, iron will be decreased due to being kept in Ferrin form- Reduced from makes it more available - To exit the cell it has to oxidized to enable binding to proteins to be able to transport it in the blood Factors increasing Fe absorption- All refer to non-heme, heme is very effected - Vit. C- by far is the strongest factor- Organic acids, including amino acids, citric acid, lactic acid - Meat fish poultry factor(MFP factor) refers to beef, chicken, fish, lamb, pork…and the cysteine content of the meats o also peptides from the digestion of myosin and actin appear to enhance absorptionall of the above keep Fe in its ferrous (Fe++) or more readily absorbed form - enhanced erythropoiesis( making of red blood cells from the bone marrow requires hormone form of kidney)o due to blood loss, hemolysis, hemorrhage, hypoxia - Fe deficient person will absorb 10-20% - Pregnancy ( particularly in the last halfFactors decreasing Fe absorption - Rapid transit time- Achlorhydria or any medical /surgical/ condition that increases gastric pH- Malabsorption syndromes- Phytate(wheat bran chelate Fe)o As little as 5-10mg of phyate can cut iron absorption in half - Clay(pica)- Tea- 60% reduction due to tannins- Coffee 40% reduction due to polyphenols - Oxalate(spinach)- Overuse of antacids precipitates Feo Phosphates and carbonates - Iron overload- Infection/ inflammation- Calcium might interfere with Fe absorption- studies are contradictory o The overall effect of Ca and Fe absorption has a huge effect on women health Iron Transport- Transferrin- most important transfer protein o Synthesized in live as apotransferrin o As Fe enters blood from intestinal mucosa, it is oxidized to Fe+++ by ceraloplasim (another circulating protein) o Apotransferrin has 2 sites that bine Fe+++ tightly to form transferrin o Transferrin transports iron to various and to the bone marrow cells  Have receptors for the synthesis of hemoglobin o Transferrin is normally an 1/3 saturated by Fe Normally transferrin conc. In blood is 2.2-3.5 g/LDeficiency- Fe deficiency is still a serious public health and medical problem that affects many people all over the world. It Is manifested aso Weakness, overall malaiseo Ill healtho Substandard performance, both physical and mentalo Poor ability to maintain body temp in a cold environment o Infants between 6 months and 2 years who are Fe deficient show Decreased responsiveness and activity, they are more fatigued, more fearful and exhibit other behavioral abnormalities, adverse psychometric development o Poor scholastic performance and concentrations in children o Decreased resistance to lead poisoning ( Fe deficiency increases Pb absorption) o Poor maternal stores may be related to Preterm delivery, higher maternal mortality o May or may not influence immunity it is not clear - Fe deficiency Anemia, the final stage of iron deficiency o Therefore w/o blood or not enough blood o There is no difference between iron deficiency and iron deficiency anemia o Iron deficiency might have:  Decrease in- Transferrin saturation - Serum ferritin- But HGB is still NORMAL o If iron deficiency continues to the point that HGB drops, ANEMIA occurs- Definition of deficiency anemia-


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