RT Book, Section
A1 Adamson, John W.
A1 Longo, Dan L.
A2 Kasper, Dennis
A2 Fauci, Anthony
A2 Hauser, Stephen
A2 Longo, Dan
A2 Jameson, J. Larry
A2 Loscalzo, Joseph
SR Print(0)
ID 1120790231
T1 Anemia and Polycythemia
T2 Harrison's Principles of Internal Medicine, 19e
YR 2014
FD 2014
PB McGraw-Hill Education
PP New York, NY
SN 9780071802154
LK accesspharmacy.mhmedical.com/content.aspx?aid=1120790231
RD 2022/07/04
AB Hematopoiesis  is  the  process  by  which  the  formed  elements  of  blood  are  produced.  The  process  is  regulated  through  a  series  of  steps  beginning  with  the  hematopoietic  stem  cell.  Stem  cells  are  capable  of  producing  red  cells,  all  classes  of  granulocytes,  monocytes,  platelets,  and  the  cells  of  the  immune  system.  The  precise  molecular  mechanism—either  intrinsic  to  the  stem  cell  itself  or  through  the  action  of  extrinsic  factors—by  which  the  stem  cell  becomes  committed  to  a  given  lineage  is  not  fully  defined.  However,  experiments  in  mice  suggest  that  erythroid  cells  come  from  a  common  erythroid/megakaryocyte  progenitor  that  does  not  develop  in  the  absence  of  expression  of  the  GATA-1  and  FOG-1  (friend  of  GATA-1)  transcription  factors  (Chap.  89e).  Following  lineage  commitment,  hematopoietic  progenitor  and  precursor  cells  come  increasingly  under  the  regulatory  influence  of  growth  factors  and  hormones.  For  red  cell  production,  erythropoietin  (EPO)  is  the  primary  regulatory  hormone.  EPO  is  required  for  the  maintenance  of  committed  erythroid  progenitor  cells  that,  in  the  absence  of  the  hormone,  undergo  programmed  cell  death  (apoptosis).  The  regulated  process  of  red  cell  production  is  erythropoiesis,  and  its  key  elements  are  illustrated  in  Fig.  77-1.