What is the primary function of hematopoietic tissue?
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Responsible for the synthesis or production of blood cells.
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What is the primary function of hematopoietic tissue?
Responsible for the synthesis or production of blood cells.
What are the primary lymphoid tissues?
Bone Marrow (produces B-cells) and Thymus (produces T-cells).
What does the bone marrow contain?
Hematopoietic cells, stromal cells, and blood vessels.
When do we examine a bone marrow specimen?
In cases of hematologic disorders affecting the cells, such as anemia, leukemia, tumors, and infections.
What are cytokines?
A group of proteins that have direct and indirect effects on hematopoietic stem cells.
What is the main function of bone marrow?
Proliferation and production of blood cells.
What type of stem cell gives rise to progenitor cells?
Pluripotent Stem Cell.
What happens when the spleen is enlarged?
More platelets are sequestered/stored, and even young & healthy cells may be affected and damaged.
What is the usual procedure for counting cells in a bone marrow specimen?
Medical technologists and pathologists usually count 500 cells that will eventually be identified and differentiated.
What functions do cytokines serve in hematopoiesis?
They prevent precursor cells from dying, stimulate stem cell division, and regulate cell differentiation.
What is yellow bone marrow?
Inactive hematopoietically, accumulates fats, and is not capable of producing blood cells.
What do Lymphoid Stem Cells produce?
Lymphocytes, including B-cells and T-cells.
What is splenectomy?
The surgical removal of the spleen, often needed if the spleen is damaged.
What are some normal cells found in bone marrow?
Macrophages, mast cells, osteoblasts, and osteoclasts.
Which cytokines have negative influences on hematopoiesis?
Transforming growth factors-beta, Tumor Necrosis Factor-alpha, and Interferon.
What is red bone marrow responsible for?
Production of developing cells and progenitors that produce mature blood cells.
What are the primary functions of the spleen?
Sequesters or stores platelets and removes unwanted or abnormal cells in blood.
What do Myeloid Stem Cells produce?
Mature cells excluding lymphocytes, including RBCs.
What is the preferred site for bone marrow collection?
The posterior iliac crest.
What is the role of Colony-Stimulating Factor (CSF)?
It regulates the production of white blood cells (WBCs).
What is hematopoiesis?
A continuous and regulated process of blood cell production resulting in the formation, development, and specialization of all functional blood cells (RBCs, WBCs, and Platelets).
At what age is bone marrow approximately 60-70% active?
In the 20s.
What are lymph nodes?
Bean-shaped structures located along the lymphatic capillaries that remove foreign blood contaminants.
What is a Colony Forming Unit (CFU)?
A colony of hematopoietic precursor cells that can survive for 5-8 weeks.
What needle is used for trephine biopsy?
Jamshidi needle (gauge size: 11).
What is Erythropoietin (EPO) and where is it derived from?
A cytokine derived from the kidneys that helps myeloid stem cells produce red blood cells (RBCs).
What happens to adipocytes in bone marrow as we age?
They become more present and occupy spaces in long bones.
What are the key processes involved in hematopoiesis?
Cell renewal, proliferation, differentiation, and maturation.
What are the two regions of lymph nodes?
Cortex (outer layer) containing B-cells and Medulla (inner layer) containing T-cells.
What is the significance of Growth Factors in stem cell commitment?
They stimulate stem cells to commit to specific cell types.
What is extramedullary hematopoiesis?
It occurs when hyperplasia of the bone marrow cannot meet the physiological needs of the body.
What is Thrombopoietin (TPO) and its source?
A cytokine derived from the liver and kidneys needed for the production of megakaryocytes, which produce platelets.
Where does hematopoiesis primarily occur in healthy adults?
In the bone marrow.
What is one of the main functions of bone marrow related to iron?
Iron storage, especially when RBCs are destroyed.
How many erythrocytes are produced daily per kilogram of body weight in a normal adult?
2.5 billion.
What is the primary function of the thymus?
Normal development of T-cells and conditioning of lymphocytes.
Which organs are involved in extramedullary hematopoiesis?
Liver, spleen, lymph nodes, and thymus.
What are Interleukins?
Signaling molecules that help progenitor cells commit to specific lineages, initially thought to be produced only by leukocytes.
What is the chief site of cell production during the mesoblastic phase?
The embryonic yolk sac.
What is the ratio of hematopoietic stem cells to nucleated blood cells?
1 hematopoietic stem cell per 1000 nucleated blood cells.
What are the two theories of stem cell hematopoiesis?
Monophyletic theory and Polyphyletic theory.
What role does the liver play in hematopoiesis?
It provides necessary proteins and essential minerals for the synthesis of DNA and RNA.
What is the role of stromal cells in hematopoiesis?
They regulate HSCs and progenitor cells, aiding in their survival and differentiation into cell lines like RBCs, WBCs, and platelets.
Which cytokines have positive influences on hematopoiesis?
Interleukins 1, 3, 6, 7, 9, 11, KIT Ligands (KITLG), and GM-CSF.
When does the hematopoietic stage begin during gestation?
As early as the 19th day of gestation.
What does the Monophyletic theory suggest?
All blood cells are derived from a single progenitor stem cell, the Pluripotential Hematopoietic Stem Cell (PHSC).
What markers identify the earliest human hematopoietic stem cells?
CD34+, CD38-, HLA-DR low, Thy1 low.
What is the major site of cell production during the second trimester of fetal development?
The liver.
What are the key types of stromal cells that support HSCs in bone marrow?
Endothelial cells, adipocytes, macrophages, osteoblasts, osteoclasts, and reticular cells.
What are the types of embryonic hemoglobins produced during the mesoblastic phase?
Gower 1, Gower 2, and Portland hemoglobins.
What does the Polyphyletic theory suggest?
Each blood cell lineage is derived from its own unique stem cell.
What does the loss of CD38 and HLA-DR indicate?
Loss of 'stemness' in producing cells.
What are the functions of the spleen?
Phagocytosis and lymphopoiesis.
What is the function of endothelial cells in the bone marrow?
They regulate the flow of particles entering and leaving the hematopoietic spaces.
What is a key feature of the mesoblastic phase?
It occurs intravascularly within developing blood vessels.
What do CD10 and CD38 markers indicate?
Committed Lymphoid progenitors.
What are Hematopoietic Stem Cells (HSCs)?
Self-renewing and pluripotent cells that can reconstitute the hematopoietic system of irradiated hosts.
What are the three types of splenic tissue?
White pulp, red pulp, and marginal zone.
How do adipocytes contribute to hematopoiesis?
They secrete steroids that influence erythropoiesis, maintain bone integrity, and regulate bone marrow volume.
When does the hepatic phase of hematopoiesis begin?
At 5 to 7 gestational weeks.
What is the significance of the myeloid to erythroid (M:E) ratio?
It compares the relative number of granulocyte precursors to erythrocyte precursors in the bone marrow.
What phase of hematopoiesis occurs after the yolk sac has discontinued its role?
The Medullary Phase.
What is the process by which mature blood cells enter peripheral circulation?
The processes are not clearly understood.
When does the hepatic phase reach its peak production?
Around the 3rd month of pregnancy (roughly 12 weeks).
What is the normal M:E ratio range?
2:1 up to 4:1.
At what month of gestation does the Medullary Phase begin?
At the 5th to 6th month of gestation.
What percentage of hematopoietic cells is considered normocellular in a stained smear?
30-70%.
What does an elevated M:E ratio indicate during infection?
It can increase from 2:1 up to 6:1 due to the need for more WBCs.
What is the chief site for hematopoiesis during the Medullary Phase?
Bone Marrow.
What characterizes hypercellular bone marrow?
An abnormal increase in the production of cells, with more than 70% hematopoietic cells.
What M:E ratio might be observed in leukemia?
It can go as high as 25:1.
What type of hemoglobin is predominant during the fetal stage?
Hemoglobin F (HbF).
What is hypocellular bone marrow?
An abnormal decrease in the production of cells, with less than 30% hematopoietic cells.
What components make up the extracellular matrix of the bone marrow?
Fibronectin, collagen, laminin, thrombospondin, tenascin, and proteoglycans.
What happens to the production of HbF after birth?
There is a decrease in the production of HbF.
What is aplastic bone marrow?
A condition with very few or a total absence of hematopoietic cells.
What are the main types of hemoglobin present in adults?
Hemoglobin A (HbA), Hemoglobin A1 (HbA1), and Hemoglobin A2 (HbA2).
What arteries supply nutrients and oxygen to the bone marrow?
Nutrient and periosteal arteries.
What cells are responsible for the development and production of blood cells in the bone marrow?
Hematopoietic Stem Cells (HSCs) and Mesenchymal cells.
What is the role of the hematopoietic microenvironment?
To nurture and protect hematopoietic stem cells (HSCs).
What is the significance of growth factors during the Medullary Phase?
They ensure that stem cells commit to the production of specific blood cells.
What does the stroma in the hematopoietic microenvironment do?
Serves as an anchor for developing hematopoietic cells and promotes cell adhesion.
Which organs are involved in hematopoiesis during the fetal stage?
Liver, spleen, kidneys, thymus, and placenta.
How does the hematopoietic microenvironment adjust during transitions in hematopoiesis?
It adjusts to provide a proper supply of nutrients needed by hematopoietic stem cells.
What is the term used for hematopoiesis occurring in the bone marrow?
Medullary Hematopoiesis.
