Block 2b Erythrocytes Flashcards
Give dimensions of a RBC.
7.8 x 2.5 microns; 1 micron at center
What is hematocrit?
fraction of blood volume taken up by RBCs
What is a normal adult Hct?
0.4 - 0.45
What is normal hematocrit in a neonate?
0.65
Normal RBC concentration in blood?
4.7 - 5.2 x 10^6 cells/uL
Which long bones produce RBCs?
tibia & femur
which bones produce RBCs in adults?
vertebrae, sternum, rib
When do long bones cease RBC production?
20 years old
What does pluripotent mean?
cell type that can differentiate into a LIMITED number of cell types
What does totipotent mean?
cell type that can differentiate into ANY cell type
What is pernicious anemia?
decreased RBC concentration caused by failure to absorb B12
What dietary elements are required for RBC production?
B12, folate
Where is EPO released?
kidney
What is the stimulus for EPO release?
hypoxic tissue
What is the effect of EPO and what is the timeframe of its effect?
hematopoiesis over period of days
What cell type does EPO drive production of?
proerythrocytes
What polypeptides make up HbA?
2 alpha, 2 beta
What are the polypeptide chains that can make up Hb?
alpha, beta, gamma, delta
What constitutes a polypeptide “chain” in Hb?
polypeptide + heme
How many iron atoms are contained in 1 Hb?
4
How is iron degraded?
Kupffer cells in liver degrade Hb to Fe + bilirubin; lost in blood & feces
How is iron sequestered in cells?
ferritin
How is iron sequestered in the blood?
transferrin
Where does transferrin act?
plasma and intestines
How is iron absorbed?
binds apotransferrin (from bile) to form transferrin, which enters intestinal epithelium thru the transferrin receptor
What is the lifespan of a RBC?
120 days in the plasma
What is aplastic anemia?
anemia caused by loss of bone marrow
What is megablastic anemia?
anemia caused by misshapen RBCs via B12 or folate deficiency
What is hemolytic anemia?
anemia caused by fragile RBCs (sickle, erythroblastosis fetalis, spherocytosis)
What is polychthemia vera?
failure to suprress RBC production leading to increases in BV and plasma colloid osmotic pressure
What scenarios can cause polycythemia?
primary scenario (adaptive response to altitude, cardiac failure), polycythemia vera, or EPO
What are functions of RBCs?
transport of Hb, blood buffering
What are the types of signaling molecules that may act on PHSCs?
growth inducers and differentiation inducers
What is the effect of a growth inducer signaling molecule?
promotes clonal expansion of committed cells
What is the effect of a differentiation inducer as a signaling molecule?
drives pluripotent stem cells to committed cells
What is an example of a growth inducer?
Il-3
What cell types can PHSCs differentiate to?
CFU-S (spleen); or lymphoid stem cell
CFU-S cells are precursors to these cells:
CFU-blast, CFU-GM, CFU-M (innate immunity cells & RBCs)
CFU-blasts go on to produce:
proerythrocytes
How do proerythrocytes change to produce an RBC?
1) nucleus condensed and extruded, 2) ER and Golgi resorbed over 48 hours, 3) RBC leaves bone marrow
What are granulocytes?
neutrophils, eosinophils, basophils
From what cell type are platelets formed?
megakaryocytes
From what cell type are macrocytes formed?
monocytes
