Hematopoiesis & Erythropoiesis Flashcards
What is hematopoiesis?
The process of making formed elements
Where do all formed elements come from?
Stem cells; hemocytoblast
Where are hemocytoblasts found?
Primarily in red bone marrow
What do hemocytoblasts differentiate into?
Either myeloid stem cells or lymphoid stem cells
What is created by the myeloid stem cells?
EVERYTHING except lymphocytes
Where is red bone marrow present?
ends of femurs and humerus, pelvic girdle, vertebral bodies, sternum, skull
What is erythropoiesis?
Formation of RBCs
Decribe the process of erythropoiesis after differentiation of hemocytoblasts
erythroblast undergoes ribosome production, creates proteins for hemoglobin; hemoglobin synthesized; cell ejects nucleus and unnecessary organelles (at this point is considered a reticulocyte); enters blood stream and binds O2 molecules and is now erythrocyte
How long does erythropoiesis take?
5-7 days
Describe the life cycle of an erythrocyte
after erythropoiesis, they enter the blood stream and circulate for ~120 days. After RBC death, cells are consumed by macrophages; hemoglobin is broken down; globin is recycled as amino acids for erythropoiesis; heme is processed in the liver: iron recycled, waste excreted as bilirubin
Why are erythrocytes so short-lived?
Since they’re anucleate, they can’t repair themselves
Decribe the control cycle of erythropoiesis
Controlled by erythropoietin/EPO (produced by kidney & liver); stimulates myeloid stem cell differentiation & Hb development; EPO release triggered by low blood oxygen
