STRUCTURE AND FUNCTION OF ERYTHROPOIETIC TISSUE. The RBCs. ERYTHROPOIESIS (RBC PRODUCTION). Mature erythrocytes are derived from committed erythroid proginator cells through a series of mitotic divisions and maturation phases. Erythropoietin , a humoral agent produced
mainly by the kidneys stimulates erythropoiesis by acting oncommitted stem cells to induce proliferation and differentiation of erythrocytes in the bone marrow.
Erythropoietic porphyria - results from excessive production of porphyrins in the bone marrow.
Hepatic porphyria - results from excessive production of porphyrins in the liver.
Lead intoxication - interferes with protoporphyrin synthesis
Chronic alcoholic liver disease
Sufficient cellular iron
Depleted cellular iron
IRE-BP has low affinity for RNA binding
IRE-BP has a high affinity for RNA binding
Translation of ferritinmRNA
Decreased stability of transferrin receptor mRNA
Translation of ALAS mRNA
Inhibits translation of ferritin RNA
Stabilizes transferrin receptor mRNA
Inhibits translation of ALAS
Decreased transferrin receptors
Heme synthesis stimulated
Increased transferrin receptors
Heme synthesis decreased