Upgrade to remove ads
Only $35.99/year

14 SEP15 - MacPherson - Hematopoiesis

Terms in this set (25)

1301 What is hematopoiesis?
Replacement of blood cells - or blood cell formation.
1302 Why is hematopoiesis necessary?
Every blood cell has a finite life span, some longer than others, but they all need to be replaced eventually.
1303 Where does hematopoeisis occur in the fetus? in the adult?
1303-1. The yolk sac, spleen and liver are hemopeoitic organs in the fetus. In mature life, only the bone marrow of certain bones, the spleen, lymph nodes and up to puberty, the thymus.
1303 What is a reticular cell?
1303-2. It is the cell responsible for secreting the reticular stroma of the marrow.
1304 What are the functions of a reticular cell?
1304-1. Secretion of a reticular fiber network, secrete several colony-stimulating factors that stimulate differentiation of stem cells in bone marrow.
What is myeloid tissue?
Myeloid tissue is a biologic tissue with the ability to perform hematopoiesis. It is mainly found as the red bone marrow in bones, and is often synonymous with this.
1304 What are the components of myeloid tissue?
1304-2. Reticular cells, fibroblasts, macrophages, adipose cells that form the stroma; venous sinusoids that allow blood cell escape (entrance into the peripheral blood) and free cells (billions of blood cells in various stages of differentiation).
1305 What is a "nest" in bone marrow?
A group of a specific type of blood cell differentiation within the stromal meshwork of the marrow.
1306 How do RBC developing nests differ from those of developing granulocytes?
RBC and platelet nests are located closer to the venous sinusoids as they are the predominate elements of peripheral blood and larger numbers need to enter the system than for other blood cell types. They are not stored in the marrow and must be positioned for immediate release.
1307 How do mature RBCs gain access to the peripheral blood?
The mature blood cells pushes against the posterior aspect of the sinusoid's endothelial lining creating an "aperture" through which they pass and enter the peripheral blood.
1308 What is a CFU, a CFC, and a CSF?
CFU - colony forming unit; CFC - colony forming cell; CFS - colony stimulating factor
1309 What is the function of each (CFU, CFC, CSF)?
CFU = a stem cell from which specific blood cell lines of the marrow arise. CFC = colony forming cells which arise from a CFU, one for each end-cell of the various types of blood cells produced. CSF = factors that control the differentiation of the various cell lines
1310 Which stages of each blood cell lineage is likely to be found in peripheral blood?
Mature blood cell types plus the immediate step prior to the mature cell (ie. reticulocyte, band cell granulocyte forms)
1311 Which stages of each blood cell lineage is likely to be found in extravascular marrow spaces?
All the various phases in blood cell development from the CFU to mature blood cells types.
1312 How are platelets formed and from which cell type do they arise directly?
Platelets form by pieces of megakaryocyte cytoplasm stripping off the mother cell.
1313 What changes occur during the differentiation of erythrocytes?
1. decrease in cell size; 2. condensation of chromatin; 3. loss of nucleus; 4. acquisition of hemoglobin.
1314 Why do erythrocytes lose their basophilia and take on acidophilia?
Basophilic erythrocytes are basophilic due to the ribosomes (rRNA). Polychromatic erythroblasts begin to change color due to the production of hemoglobin


As the cell fills with hemoglobin (an acidophilic component thus attracting basophilic dyes), the need for the synthetic apparatus that produced it (the rER) is less and it was once highly acidophilic attracting basophilic dyes.
1315 List the stages involved in erythropoeisis.
proerythroblast - basophilic erythroblast - polychromatic erythroblast - orthochromatic erythroblast (normoblast) - reticulocyte - red blood cell (erythrocyte).

PBPORR
1316 What structural/color features are associated with each stage of erythroid development?
- proerythroblast: not distinguishable
- basophilic erythroblast: dense chromatin and intense blue cytoplasm
- polychromatic erythroblast: pale nucleus with grey to grey-blue cytoplasm
- orthochromatic erythroblast (normoblast): erythroblast-color cytoplasm, dark pyknotic nucleus
- retyiculocyte: erythroblast-color cytoplasm, no nucleus, faint blue strands of rER,
- red blood cell (erythrocyte).
1317 What changes occur during the differentiation of granulocytes?
1. decreased cell size; 2. increased lobulation of nucleus; 3. increased number of specific granules.
1318 List the cell stages involved in granulopoiesis.
Promyelocyte, myelocyte, metamyelocyte, band form, mature (segmented) granulocyte

PMMBM
1319 What structural/color features are associated with each stage of myeloid development?
Promyelocyte: round/oval nucleus, basophilic cytoplasm
myelocyte: specific granules first appear, round/ovoid nucleus
metamyelocyte: indented nucleus, granule numbers increases
band form: deeply-indented C-shaped nucleus
1320 Where does lymphopoeisis occur?
lymphopoiesis occurs in bone marrow as well as in lymphoid organs (spleen, lymph nodes, thymus).
1321 Which specific blood cells are formed from lymphopoeisis?
lymphocytes
1322 In the RBC and granulocyte lineages, what are the last stages that can still undergo mitosis?
Erythroid lineage: Polychromatic erythroblast

Myeloid lineage: Myelocyte
Sets found in the same folder