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24 Cards in this Set
- Front
- Back
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blood composition |
cellular -erythrocytes (hematocrit: males 44%, females 40%, infants 50%) -leukocytes -granulocytes -lymphocytes -platelets
plasma -clotting factors -immunoglobulins -albumin |
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RBC size and features |
-small (7-8 microns in diameter; 0.8 microns thick at center, 1.6 microns thick at edge) -biconcave disk (center is central palet) -stains acidophilic -anucleated -same diameter as leukocyte nucleus -too small : microcytic; too big: macrocytic -variation in size = anisocytosis |
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reticulocytes |
-young RBC -anucleated, but slightly basophilic due to remaining mRNA being translated to hemoglobin -slightly larger -normally about 1% of the RBC population (increases during high RBC production) |
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function of RBCs |
transport oxygen -requires ability to bind oxygen tightly in the lung and release it at the tissues --> hemoglobin -they are deformed (squished) through capillaries with smaller diameter to allow interaction of membranes and gas exchange to take place |
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Hgb |
hemoglobin -tetramer; two alpha and two beta chains -each subunit binds a heme -heme is a ferrous (Fe2+) binding ring structure, where the iron binds oxygen -binds oxygen coopratively (relaxed state has high affinity, taut state has low affinity) -affinity is altered by allosteric factors (e.g. temp, pH, 2,3-DPG, and pCO2); right shift during metabolic action |
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hemoglobin isoforms |
-fetus makes HgbF (alpha1gamma2) (resistant to 2,3-DPG) -embryo makes many isoforms -adult makes mostly HgbA (alpha2beta2) -small amount of HgbA2 in adults (alpha2delta2) -mutations in the beta chain cause hemoglobinopathies such as HgbS (sickle), which alters the solubility --> pathology |
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RBC life span |
-120 days -100,000 circulations -produces wear and tear --> macrophages will remove bad RBCs at capillaries |
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RBC specializations |
-highly specialized membrane: cholesterol and phospholipids with transporters for glucose, ions, and bicarbonate -specialized cytoskeleton: includes spectrin (supportive hexagonal meshwork just below membrane) which forms complexes with ankyrin and band4.1 which are anchored to integral membrane proteins band 3 and glycophorin C |
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RBC shape |
-biconcave discs -many potential (generally problematic) variations; e.g. elliptocytes, spherocytes, target cells, sickle cells, schistocytes -variation in shape = poikilocytosis |
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anisocytosis |
variation is size of RBCs |
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poikilocytosis |
variation in shape of RBCs |
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routinely measured RBC parameters |
-mean cell volume -mean cell hemoglobin -mean cell hemoglobin concentration -red cell distribution width (measure of the distribution of mean cell volume) |
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2,3-DPG |
2,3-diphosphoglycerate -derived from glycolytic intermediates -regulates the affinity of Hgb for O2 -shifts curve rightward, causing O2 to dissociate more rapidly -made in response to increased hypoxia, anemia -takes hours to days to increase amounts --> adaptive response |
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CO poisoning |
-binds heme iron with higher affinity than O2 -shifts O2 dissociation curve left |
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methemoglobin |
-iron in ferric state due to oxidative stress (drugs, toxins) -cannot transport oxygen -cyt B5 can reduce ferric iron back to ferrous with NADH |
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RBC handling of other ROS |
-superoxide dismutase -catalase -glutathione (reduces hydrogen peroxide; uses NADPH from pentose pathway to recycle back) |
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hemoglobin A1C |
-glycated Hb -nonenzymatic -proportional to blood glucose levels -integrated measure of glucose control over prolonged period |
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the spleen role in RBC |
-cell that has lost flexibility cannot squeeze between the specialized endothelial cells -most of cell becomes bilirubin and goes to liver to be degraded |
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spectrin |
-band 1 -gives the RBC its elasticity -all around the membrane in a meshwork |
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ankyrin |
anchors spectrin to membrane |
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band 3 |
-anion exchanger important for moving bicarbonate in and out -integral membrane protein |
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band 4.1 |
-anchors spectrin to the membrane -binds to integral membrane proteins |
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hereditary elliptocytosis |
-due to spectrin mutations -most patients are asymptomatic -confers resistance to malaria |
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herediitary spherocytosis |
-abnormal RBC shape -shortened lifespan -caused by mutations in: spectrin, ankyrin, or band 3 |
