RBC Structure and Function Flashcards
Blood is
Connective Tissue
Derived from mesoderm
Function of Circulating Blood
Deliver Oxygen
Control Infection
Requirement for hemostasis
Most Sensitive Organs to O2
Brain
Heart
Kidney
What is Hematocrit?
the volume percentage of RBC in blood
Males 44%
Females 40%
Infants 50%
RBC size and shape
7-8 microns
biconcave disc
stain acidophillic (red)
Anucleated
Young Red Blood Cell
Reticulocyte
Anisocytosis
Variation in size
Poikilocytosis
Variation in shape
Chromicity
RBC color
Mean Cell Volume
Average volume of RBC
80-100fl
Mean cell hemoglobin
Average amount of hemoglobin per RBC
Mean Cell hemoglobin concentration
measures amount of hemoglobin in the cell relative to its size
If you just measured hemoglobin one could have very macrocytic RBCs that indicate high hemoglobin
MCHC factors in size of RBC
Red Cell distribution width
Make sure cells have tight distribution
i.e. all the cells fall within the same size
Hemoglobin
Oxygen and binding delivery
Tetrameric: 4 subunits (globin + heme)
2 alpha -globin
2 beta - globin
Hemoglobin vs. Myoglobin
Hemoglobin shows cooperativity and has a sigmoidal curve
Myoglobin, found in muscle, does not show cooperativity and has a hyperbolic curve
NB: myoglobin has a higher binding affinity for O2
Right Shift
Decrease affinity for oxygen
What causes Right shift?
Increase Temp
Increase CO2
Increase 2,3 DPG
Low pH
Left Shift
Increase affinity for oxygen
What causes Left Shift?
Decrease Temp
Decrease CO2
Decrease 2,3 DPG
High pH
2,3 Diphosphoglycerate
2,3DPG
derived from glycolytic intermediate
regulates the affinity of Hgb for O2
Increase shifts curve to the right
2,3DPG is competitive inhibitor for O2 and makes O2 dissociate more easily
R State
Relaxed binds oxygen more easily
T state
Tense state binds oxygen less readily
What amino acid does heme interact with
Histadine
CO poisoning
Binds to heme iron
240 fold higher affinity than O2
Shifts O2 dissociation curve to the LEFT
Major and Minor genes for Adult Hemoglobin
Major:
alpha 2; beta 2
Minor
alpha 2; delta 2
Fetal Hemoglobin composition
alpha 2; gamma 2
fetal hemoglobin is resistant to 2,3DPG
HbF has higher O2 affinity than adult
Sickle Cell Anemia
Glu 6 Val
Valine substitution for glutamine
Hb becomes insoluble when DEOXYGENATED
Methemoglobin
Iron in Hb: Ferrous Fe2+
Oxidative Stress causes transition to Fe3+ Ferric
Methemoglobin has Fe3+
Methemoglobin cannot transport O2!!!!
Methemoglobin Reaction
Cyt b5ox + NADH –> Cyt b5red + NAD
Cyt b5red + Hb-Fe3+ –> Cyt b5ox + Hb-Fe2+
occurs via methmoglobin reductase
Superoxide Dismutase
O2 Radical –>H2O2 + H2O
Catalase
H2O2 –> H2O + O2
gets rid of hydrogen peroxide
Glutathione
2GSH + H2O2 –> GSSG + 2H2O
GSSG + NADPH –> 2GSH + NADP
gets rid of hydrogen peroxide
Hemoglobin A1C
Glycated Hb
Non-enzymatic
Proportional to blood glucose levels
Integrated measure of glucose control over prolonged period
Spectrin
Gives RBC rubber like flexability
Ankyrin and Band 4.1
Anchor spectrin to the membrane
Band 3
anion exchanger important for moving bicarbonate in and out of cell
Cytoskeletal Organization of RBC
Band 3 is found in the membrane
Ankyrin binds to band 3
Ankyrin/ Band 3 complex can bind to sepctrin
Spectrin forms hexagonal lattice beneath plasma membrane
Heriditary Elliptocytosis
Caused by mutation in spectrin
