● The number of RBC's is tightly regulated
: the human body needs sufficient RBC's for O2
transport, but too many RBC's would cause the blood to become like "sludge," which places an enormous load on the heart.
● In cardiac failure (↓cardiac output) and many respiratory diseases, RBC production is stimulated to compensate for ↓O2 delivery
● Erythropoietin (a hormone) or hypoxia
stimulates the production of proerythroblasts
and ↑rate of the maturation process. It typically takes ~5 days for new mature RBC's
to appear in the blood and production can increase up to x10!
● RBC's typically have a ½-life
of ~100 - 120 days and therefore the predecessors of RBC's are among the most rapidly dividing cells in the body
. Nutrition is therefore very important (iron
and B vitamins
● However, because of the rapidly dividing process of RBC predecessors, these cells are often significantly affected by cancer chemotherapy
which attempts to target the rapidly-growing tumor cells, but ends up also targeting rapidly dividing blood cells, thus inducing chemotherapy-related anemia
● Vitamin B12
and Folic acid
are necessary for DNA synthesis and a deficiency results in "maturation failure
" and the production of abnormal RBC's called macrocytes. Macrocytes
do not have the correct/strong/deformable shape of normal RBC's and are often fragile with a significantly reduced ½-life.