Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
84 Cards in this Set
- Front
- Back
What is the normal adult daily iron needed to replace senescent RBCs?
Where does most come from? What is avg intake? |
Normal adult = 21 mg
most comes from recycling iron. Pregnant/breast feeding/infants need more. Avg intake = 10-20 mg/day |
|
how much of the total body iron is present as hemoglobin?
|
66%
|
|
How much iron is absorbed from diet and lost daily?
|
both = 1-2 mg
|
|
What factors affect daily Fe requirements?
|
growth spurts
menstruation pregnancy lactation iron deficiency |
|
where is dietary iron absorption regulated?
|
in the intestinal mucosa of the small bowel
|
|
What is the oxidation state of iron in:
-diet -stomach -mucosal cells |
Dietary is Ferric - 3+
Stomach is Ferrous - 2+ Mucosa - back to 3+, then complexed with apoferritin to form Ferritin - storage form of iron |
|
What is the primary storage form of iron, and where is it found?
Why is it primary? |
ferritin
-liver, spleen, bone marrow. Easily mobilized for usage |
|
What is an alternative form of stored iron to ferritin?
|
hemosiderin
|
|
After Fe3+ in mucosal cells is complexed with apoferritin, what is the remaining Ferric iron converted to?
|
Transferrin, via combination with apotransferrin.
|
|
what is Transferrin?
|
an Iron transporter to the organs in the body.
|
|
What forms Heme?
|
Iron plus Protoporphyrin ring
|
|
How is iron absorption regulated by mucosal cells?
|
they only take up ferrous iron, so it has to be converted by the stomach acid to Fe2+. After uptake, its converted back to Fe3+ - ferric.
|
|
What is Fe3+ first complexed with in mucosal cells?
|
apotransferrin, to be transferred to the blood.
|
|
What is apotransferrin?
|
transferrin without Iron. just a glycoprotein Beta-globulin shell without its prosthetic group
|
|
What does transferrin do?
|
transports iron from the gut to the blood
|
|
What are the 2 storage forms of iron?
|
ferritin
hemosiderin |
|
what is the primary protein used to store iron, but without the prostethic group?
|
Apoferritin.
|
|
what is ferritin?
|
the storage form of iron - it complexes with Ferric Iron to make it Fe2+
|
|
where is ferritin found?
|
bone marrow
spleen liver plasma intestinal mucosal cells (some) |
|
what is hemosiderin?
|
a storage form of ferritin - the ferritin is denatured, but there is excess Fe within it.
|
|
what does hemosiderin stain with?
|
prussian blue.
|
|
where is the majority of Fe found in the body?
|
blood - 65% is in hemoglobin
stored - 30% is in ferritin/hemosiderin |
|
what are 5 types of iron studies?
|
1. serum iron
2. Total iron binding capacity (TIBC) 3. % saturation of transferrin 4. Serum ferritin 5. Free erythrocyte protoporphyrin (FEP) |
|
What is serum iron?
Reference range? What is it used for? How does it vary? |
iron bound to protein.
Ref range = 60-160 mg/dl It has limited use as a single measurement. Diurnal variation - different in the morning vs. night |
|
What is TIBC? what info does it give?
|
Total Iron Binding Capacity, tells how much transferrin is able to bind Iron.
So, an indirect measurement of transferrin. |
|
What is the ref range of TIBC?
|
200-360 mg/dl
|
|
what does a high TIBC indicate?
|
That lots of transferrin is free and capable of binding iron - b/c iron to be transferred is low.
|
|
what is the % Saturation of Transferrin test?
|
meausres serum iron/TIBC x 100 to detect if iron levels are too high.
|
|
what is serum ferritin?
|
an acute phase reactant, increased in inflammation.
|
|
What info does serum ferritin measurement give?
what is its clinical use? limitations? |
measurement of body iron stores.
used for monitoring iron therapy. an acute phase reactant, can be falsely elevated in inflammation. |
|
What does FEP or ZPP stand for?
|
Free erythrocyte protoporphyrin, or
Zinc protoporphyrin |
|
What does FEP represent?
What is its clinical use? |
free erythrocyte protoporphyrin - the non-heme porphyrin in BLOOD. most is actually bound to zinc, so called ZPP.
used to differentiate anemias -ZPP is increased if truly Fe deficient. |
|
what kinds of iron study results are seen in Fe deficiency anemia?
|
everything is low except
-Iron binding capacity -Free erythrocyte protoporphyrin |
|
What is characteristic iron study in Anemia of Chronic Infection?
|
high FEP - no iron is available to bind protoporphyrin so it's bound to zinc.
|
|
What is hemociderosis?
What causes it? |
Disease where ferritin is degenerated, resulting in excess iron levels.
caused by hemolysis/excess Hb breakdown. |
|
What is hemochromatosus?
What causes it? What are the symptoms? How is it treated? What iron study results are seen? |
the most common genetic abnormality i caucasions. Ferritin problem; Iron accumul up to 4g/day!! daily need is in Millig.
caused by 2-gene mutation: C2824, H63D. Symptoms: Liver cirrhosis, cardiac, diabetic, skin bronzing. BLEED THEM. EVERYTHING IS ELEVATED except TIBC. |
|
what are 4 examples of disease assocaited with iron deficiency or increase?
|
-Fe deficiency anemia
-Anemia of chronic infection -Hemociderosis -Hemochromatosis |
|
where is Heme synthesized?
|
Mitochondria
|
|
What is heme synthesized from?
|
glycine and succinyl coenzyme A
|
|
In general, how is heme synthesized?
|
it goes through a biosyntheitc pathway catalyzed by a series of enzymes in both the mitochondria and cytoplasm.
Each enzymatic reaction adds a ring to the heme molecule. It becomes less H2O soluble as it grows. Lack of an enzyme causes deficiency in heme. |
|
What is the final structure of heme?
|
a Tetrapyrole ring with Ferrous iron as its core
|
|
what controls heme synthesis?
|
ALA synthase - the rate-limiting step in the pathway.
|
|
what affect does Free heme have?
|
it can be measured in the urine.
|
|
What are the porphyrias?
What is their clinical effect? |
Defects in porphyrin synthesis.
Free porphyrin precursors are excreted in the urine as: -urobilinogen in organic layer -prophyrobilinogen in aqueous layer. |
|
Where does globin synthesis occur?
|
in ribosomes
|
|
what are the 4 types of globin chains?
|
alpha
beta gamma delta |
|
when is most alpha globin made?
|
in the fetus
|
|
what regulates globin synthesis?
|
mostly genetics
|
|
what is the structure of hemoglobin, and how is it assembled?
|
a tetramer
-2 alpha chains, 2 non-alpha. either Beta, delta, or gamma. Tetramer links to heme via the proximal histadine on the polypeptide chain. |
|
what's the most important factor affecting O2 release to tissues?
|
2,3-DPG
|
|
how is 2,3-dpg generated?
|
via anaerobic glycolysis
|
|
what four things cause a LEFT shift of dissoc. curve?
|
high Hgb F concentration
hemoglobinopathies meth or carboxyhemoglobin transfusion of 2,3-DPG depleted blood |
|
what 3 things cause a RIGHT shift?
|
hypoxia
high altitude severe anemia |
|
what 3 enzymes play a role in Hgb metabolism?
|
-enzymes of the Embden Meyerhof produce ATP!!
-G-6-PD catalyze reactions in the hexose monophosphate HMP shunt to prevent buildup of bad peroxides. W/out, Heinz bodies -Cyto b5 reductase reduces methemoglobin. |
|
what organelle is each synth in?
-heme -globin |
heme is in mitochondria
globin is in ribosomes. |
|
what regulates heme synthesis?
|
ALA-synthase
|
|
what is ALA-synthase?
|
an enzyme that catalyzes the rate-determining step in the heme production pathway
|
|
how is heme production regulated?
|
by a negative feedback system; when heme is present, expression of ALA synthase is downregulated.
|
|
what are siderocytes?
|
cells with precipitated iron, due to abnormal/faulty incorporation of iron into the heme group.
|
|
what symptomology is seen in the porphyrias?
|
metabolic deficiencies; urinary excretion of urobilinogen (organic layer), and prophyrobilinogen (aqueous)
|
|
what type of iron studies are seen in iron def. anemia?
|
decreased everything except TIBC and FEP.
|
|
what iron study results indicate anemia of chronic infection?
|
decreased serum iron, TIBC, and transferrin saturation.
increased serum ferritin and FEP. |
|
what is wrong in anemia of chronic infection?
|
no problem with iron absorption/storage, but there is faulty delivery of iron to RBC and no incorporation into heme.
-That explains the incr. serum ferritin - it's all stored. |
|
what is hemochromatosis essentially?
|
overloaded iron stores - a genetic disease.
|
|
what iron study results are seen in hemachromatosis?
|
increased serum iron, Transferrin saturation, serum ferritin.
decreased TIBC and FEP. |
|
what does 2,3-dpg do?
|
decreases hemoglobin's affinity for oxygen - makes it release.
|
|
at what pressure does hgb release oxygen in tissues?
how much is released? |
releases 25% of oxygen at 40 mm Hg.
|
|
what does temperature increase do to the o2 diss curve?
temp decrease? |
increase = shift to right
decrease = shift to left |
|
what does ph decrease (acid) do to the o2 diss curve?
ph increase (alkaline)? |
acid = shift to right
alkaline = shift to left |
|
what does increased CO2 do to the o2 diss curve?
|
shift to left
|
|
what does decrease in 2,3 DPG do to the o2 diss curve?
|
shift to left
|
|
what happens to oxygen affinity when curve shifts?
|
to the right = lower oxygen affinity
to the left = higher oxygen affinity |
|
through what metabolic pathway do RBCs generate energy?
|
embden-meyerhof.
|
|
what do RBCs need to protect themselves from?
|
oxidizing agents that are harmful to protein
|
|
what shunt is used to defend the RBC against oxidative injury?
|
Hexose-Monophosphate shunt
|
|
what is the role of glutathione in the hexose-monophosphate shunt?
|
glutathione reduces oxidative agents and neutralizes them.
|
|
what does G-6-PD do?
what is seen if it's deficient? |
an enzyme that reduces NADP to NADPH to keep the shunt going.
If deficient, see Heinz bodies. |
|
What is the purpose of Cytochrome b5 reductase?
|
reduces methemoglobin to make it capable of o2 transport.
|
|
.
|
.
|
|
.
|
.
|
|
.
|
.
|
|
.
|
.
|
|
.
|
.
|
|
.
|
..
|