Exam 1 Review:  Chapter 17:  Hematopoiesis

hematopoiesis  = hemopoiesis - The formation of blood, i.e., the developmental processes of the formed elements in blood, in the red bone marrow from the descendants of the pluripotent hemopoietic stem cell by the processes of proliferation and differentiation; each stem cell can give rise to as many as 2¹¹ mature cells.

erythropoiesis - The formation of red blood cells, i.e., the developmental processes of the red blood cell, in the red bone marrow from the descendants of the proerythroblast stem cell by the processes of proliferation and differentiation; each hemocytoblast stem cell can give rise to as many as 2¹¹ mature cells.

stem cell = blast cell - Any immature, undifferentiated, unspecialized cell, capable of repeated cell divisions (proliferation), which can replace itself, and, by differentiation, give rise to one or more specific specialized mature cell types, such as blood cells.

hemocytoblast = pluripotent hemopoietic stem cell - The primordial stem cell of red bone marrow which is capable of developing into any type of blood cell.

proerythroblast - The earliest stem cell (derived from the hemocytoblast = pluripotent hemopoietic cell) found in the red bone marrow which is committed to develop into a red blood cell.

reticulocyte - The final form of the immature red blood cell which is slightly larger than a mature RBC; it has extruded its nucleus but still contains a network of basophilic (takes up the basic blue-purple stain) filaments, which represent the sites (ribosomes) of final hemoglobin synthesis; primarily they are found in the red bone marrow but a few (0.2-2.0% of total RBCs) are found in the circulating blood; an increase in their numbers in the blood indicates increased RBC proliferation in the red bone marrow.

megakaryocyte - The largest cell found in red bone marrow, it is the source of blood platelets; it has a characteristic appearance including a lobulate polyploid nucleus; it gives rise to three to four thousand platelets which are membrane-bound fragments shed from its cytoplasm into the blood circulation.

hemopoietic growth factor - Any of the various regulatory proteins which promote the growth, organization, and maintenance of red bone marrow and blood cells.

erythropoietin = EPO - A glycoprotein hormone which stimulates the production of red blood cells by stem cells in the red bone marrow; it is produced mainly by the kidneys at the juxtaglomerular apparatus; it is released in response to decreased levels of oxygen detected in the blood in the afferent arteriole in the nephron.

cytokines - Any of several regulatory proteins, such as the interleukins and lymphokines, which are local hormones (paracrines and autocrines) released by cells of the immune system and act as intercellular mediators in the generation of an immune response.

colony stimulating factors - Any of several regulatory glycoproteins which are local hormones (a functional category of cytokines) released by cells of the immune system and act as intercellular mediators in the proliferation, i.e., cell divisions, of erythrocytes and leukocytes; these mediators are used therapeutically to enhance the success of bone marrow transplants, etc.

interleukins - Any of the dozen regulatory proteins which are local hormones (a functional category of cytokines) released by a variety of cells including lymphocytes and monocytes, especially by T lymphocytes = T cells, of the immune system and act as intercellular mediators in an immune response.

thrombopoietin (Tpo) - A glycoprotein growth factor released by the liver, kidney and bone marow, in response to a reduction in circulating platelets; it targets the committed stem cells in the megakaryocyte lineage in red bone marrow to differentiate and proliferate so that platelet production will increase to restore homeostasis.

Sketch and Label:

1. A diagram of the process of hematopoiesis.

[Note:  You are not responsible for knowing the names of the immune regulatory substances, interleukins, etc., indicated in some of the diagrams below.  Nor are you responsible for knowing the names of the intermediate stem cells in the various lineages except for the nucleated RBC and reticulocyte, the immediate precursors to the mature RBC, in the erythrocyte lineage and the "stab" or "band" cell, the nickname for the immediate precursor to the neutrophil in the granulocytic lineage.]

2. A diagram of the negative feedback regulation of erythropoiesis.

Describe:

3. The life cycle of an RBC from production ("birth") to elimination ("death"), (including the processing of hemoglobin).  Use the correct terminology.