When an
animal or a person is placed in an atmosphere of low
oxygen, erythropoietin begins to be formed within
minutes to hours, and it reaches maximum production
within 24 hours. Yet almost no new red blood cells
appear in the circulating blood until about 5 days later.
From this fact, as well as other studies, it has been
determined that the important effect of erythropoietin
is to stimulate the production of proerythroblasts from
hematopoietic stem cells in the bone marrow. In ad-
dition, once the proerythroblasts are formed, the
erythropoietin causes these cells to pass more rapidly
through the different erythroblastic stages than they
normally do, further speeding up the production of
new red blood cells. The rapid production of cells con-
tinues as long as the person remains in a low oxygen
state or until enough red blood cells have been pro-
duced to carry adequate amounts of oxygen to the
tissues despite the low oxygen; at this time, the rate of
erythropoietin production decreases to a level that will
maintain the required number of red cells but not an
excess.
In the absence of erythropoietin, few red blood
cells are formed by the bone marrow. At the other
extreme, when large quantities of erythropoietin
are formed available, and if there is plenty of iron and
other required nutrients available, the rate of red
blood cell production can rise to perhaps 10 or more
times normal. Therefore, the erythropoietin mecha-
nism for controlling red blood cell production is a
powerful one.
animal or a person is placed in an atmosphere of low
oxygen, erythropoietin begins to be formed within
minutes to hours, and it reaches maximum production
within 24 hours. Yet almost no new red blood cells
appear in the circulating blood until about 5 days later.
From this fact, as well as other studies, it has been
determined that the important effect of erythropoietin
is to stimulate the production of proerythroblasts from
hematopoietic stem cells in the bone marrow. In ad-
dition, once the proerythroblasts are formed, the
erythropoietin causes these cells to pass more rapidly
through the different erythroblastic stages than they
normally do, further speeding up the production of
new red blood cells. The rapid production of cells con-
tinues as long as the person remains in a low oxygen
state or until enough red blood cells have been pro-
duced to carry adequate amounts of oxygen to the
tissues despite the low oxygen; at this time, the rate of
erythropoietin production decreases to a level that will
maintain the required number of red cells but not an
excess.
In the absence of erythropoietin, few red blood
cells are formed by the bone marrow. At the other
extreme, when large quantities of erythropoietin
are formed available, and if there is plenty of iron and
other required nutrients available, the rate of red
blood cell production can rise to perhaps 10 or more
times normal. Therefore, the erythropoietin mecha-
nism for controlling red blood cell production is a
powerful one.