An analogous formula applies to the case of a continuous probability distribution. Not every probability distribution has a defined mean; see the Cauchy distribution for an example. Moreover, for some distributions the mean is infinite: for example, when the probability of the value is for n = 1, 2, 3, ....
Red blood cell (RBC) production (erythropoiesis) takes place in the bone marrow under the control of the hormone erythropoietin (EPO). Juxtaglomerular cells in the kidney produce EPO in response to decreased O 2 delivery (as in anemia and hypoxia) and increased levels of androgens.
The red bone marrow also warehouses plasma cells, which are integral to immune function (not related to the PLASMA that forms the fluid base of blood). The red bone marrow is the location where B-cell lymphocytes, which migrate to the marrow from the LYMPH tissues that produce them, come to maturity. Yellow bone marrow produces a few leukocytes in adulthood though primarily functions as a reserve resource for new blood cell production when the red bone marrow cannot meet the bodyâs needs.