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Heme Lec 10

MLS Heme Lec 10

Hemoglobin consist of 4 globin protein chains containing a heme component nestled in a hydrophobic crevice
Heme is what shape tetrapyrrole ring with ferrous iron in the center
Heme carries how many oxygen 1
Hemoglobin can carry how many oxygen 4
65% of hemoglobin synthesis occurs during the nucleated stages of RBC maturation
35% of hemoglobin synthesis occurs during the reticulocyte stage
Heme 4 groups each one contains a protoporphyrin ring plus ferrous iron
Globin tetramer of two pairs of unlike globin polypeptide chains
Normal production depends on 1. iron delivery and supply 2. synthesis of protoporphyris (heme precursor) 3. globin synthesis
Large hemoglobin molecules give RBCs color and most of the cell weight
Hemoglobin's most important function oxygen and carbon dioxide transport
What 3 elements must be present to make hemoglobin globin chains heme molecule iron
Hypochromic and Microcytic cells are formed because the hemoglobin is defective
Thalassemia defective globin chains
Iron deficiency anemia lack of iron (most common)
Sideroblastic anemia lack of heme
How much of the body's iron is bound to heme 2/3
How much iron is needed daily 1mg of iron for each mL of RBCs, 20-25 daily
How much iron is present as tissue iron 1/3
How much iron is in storage 90% ferritin, hemosiderin
How much iron is unavailable 10% myoglobin, cytochrome enzymes
Total body iron content of an adult 3500mg
Normal Iron Metabolism body iron is repeatedly recycled tightly regulated process daily intake, absorption, & losses are very small
Life span of RBC 120 days
Healthy adult blood volume 4500-5000mL
2mL blood contains how much iron 1mg
How much blood is lost to senescence daily 37-42mL
How many mg of iron is needed each day to replace the iron lost to senescent RBCs 18.5-21mg
Iron from RBC turnover is reutilized via the mononuclear phagocytic system
Of the 15mg intake of iron per day how much is absorbed 5-10%
To make up for iron deficiency food has been fortified with iron
Foods highest in iron organ meats wheat germ brewer's yeast legumes
Foods moderate in iron muscle meats fish fowl prunes cereals some green vegetables
Compounds that increase absorption of iron fructose amino acids ascorbic acid (vitamin C)
Compounds that decrease absorption of iron phosphates (antacids) milk
Factors which affect daily iron requirements growth spurts menstruation pregnancy lactation and breast feeding iron deficiency
Women and children are most prone to increased dietary needs (IDA)
Iron is absorbed in the duodenum of the jejunum
Most common dietary form of iron ferric (Fe+3)
Ferric iron is converted into the ferrous (Fe+2) by acid in the stomach
Ferrous iron enters the mucosal cells of the intestine where it is Converted back to ferric iron Complexes with apoferritin to form transferrin
Heme iron is also present as myoglobin and hemoglobin
Myoglobin and hemoglobin (iron in dietary meat) is more readily absorbed by mucosal cells absorbed as intact heme molecules iron is free and utilized
Tranferrin (protein carrier) delivers ferric iron to RBC precursor
Where is ferric iron (Fe+3) is changed to ferrous iron (Fe+2) mitochondria
How does transferrin transport ferric iron crosses cell membrane enters the cytoplasm goes to mitochondria delivers ferric iron
The delivered iron will be incorporated into hemoglobin
Amount of ferrtin depends on the amount of iron needed to make hemeoglobin
Ferritin storage form of iron
Why must iron have a hydrophobic pocket it must be prevented from oxidizing
Heme synthesis begins where and what does it do mitochondria with the formation of protoporphyrin synthesis
Protoporphyrin synthesis Glycine ALA + Succinyl Coenzyme A = delta-aminolevulinic acid
Enzymatic steps are influenced by erythropoietin vitamen B6
Heme synthesis I ALA->PGB->URO->Cop->Pro+Fe = heme
Each enzyme step yields unstable substances called porphyrinogens
Porphyrinogens change into oxidized to a more stable substance called porphyrins
Conversion of protorphyrin IX, iron is incorperated to yield heme
Heme synthesis II Glycine ALA + Succinyl CoA->->-> Protoporphryn IX/ring + Ferrochelatase -> Heme
Popyrias metabolic disorders Test for genetic deficiencies in enzymes Accumulate in bone marrow, brain, & liver
Cause of excess porphyria blockage of any enzymatic pathway
Impaired protpporphoryn synthesis causes iron accumulation in the cytoplasm as ferritin aggregates
Sideroblast iron-laden, nucleated RBC
Siderocytes non-nucleated form
Ringed Sideroblast mitochondria become encrusted with iron and is visible around the nucleus of the RBC precursor
What stain must be used to view iron in a cell prussian blue
Created by: mlrlemons